三维建模毕业论文英文文献翻译

外文资料翻译—原文部分Fundamentals of Human Animation(From Peter Ratner.3D Human Modeling and Animation[M].America:Wiley,2003:243~249)If you are reading this part, then you have most likely finished building your human character, created textures for it, set up its skeleton, made morph targets for facial expressions, and arranged lights around the model. You have then arrived at perhaps the most exciting part of 3-D design, which is animating a character. Up to now the work has been somewhat creative, sometimes tedious, and often difficult.It is very gratifying when all your previous efforts start to pay off as you enliven your character. When animating, there is a creative flow that increases gradually over time. You are now at the phase where you become both the actor and the director of a movie or play.Although animation appears to be a more spontaneous act, it is nevertheless just as challenging, if not more so, than all the previous steps that led up to it. Your animations will look pitiful if you do not understand some basic fundamentals and principles. The following pointers are meant to give you some direction. Feel free to experiment with them. Bend and break the rules whenever you think it will improve the animation.SOME ANIMATION POINTERS1. Try isolating parts. Sometimes this is referred to as animating in stages. Rather than trying to move every part of a body at the same time, concentrate on specific areas. Only one section of the body is moved for the duration of the animation. Then returning to the beginning of the timeline, another section is animated. By successively returning to the beginning and animating a different part each time, the entire process is less confusing.2. Put in some lag time. Different parts of the body should not start and stop at the same time. When an arm swings, the lower arm should follow a few frames after that. The hand swings after the lower arm. It is like a chain reaction that works its way through the entire length of the limb.3. Nothing ever comes to a total stop. In life, only machines appear to come to a dead stop. Muscles, tendons, force, and gravity all affect the movement of a human. You can prove this to yourself. Try punching the air with a full extension. Notice that your fist has a bounce at the end. If a part comes to a stop such as a motion hold, keyframe it once and then again after three to eight or more keyframes. Your motion graph will then have a curve between the two identical keyframes. This will make the part appear to bounce rather than come to a dead stop.4. Add facial expressions and finger movements. Your digital human should exhibit signs of life by blinking and breathing. A blink will normally occur every 60 seconds. A typical blink might be as follows:Frame 60: Both eyes are open.Frame 61: The right eye closes halfway.Frame 62: The right eye closes all the way and the left eye closes halfway.Frame 63: The right eye opens halfway and the left eye closes all the way.Frame 64: The right eye opens all the way and left eye opens halfway.Frame 65: The left eye opens all the way.Closing the eyes at slightly different times makes the blink less mechanical.Changing facial expressions could be just using eye movements to indicate thoughts running through your model's head. The hands will appear stiff if you do not add finger movements. Too many students are too lazy to take the time to add facial and hand movements. If you make the extra effort for these details you will find that your animations become much more interesting.5. What is not seen by the camera is unimportant. If an arm goes through a leg but is not seen in the camera view, then do not bother to fix it. If you want a hand to appear close to the body and the camera view makes it seem to be close even though it is not, then why move it any closer? This also applies to sets. There is no need to build an entire house if all the action takes place in the living room. Consider painting backdrops rather than modeling every part of a scene.6. Use a minimum amount of keyframes. Too many keyframes can make the character appear to move in spastic motions. Sharp, cartoonlike movements are created with closely spaced keyframes. Floaty or soft, languid motions are the result of widely spaced keyframes. An animation will often be a mixture of both. Try to look for ways that will abbreviate the motions. You can retain the essential elements of an animation while reducing the amount of keyframes necessary to create a gesture.7.Anchor a part of the body. Unless your character is in the air, it should have some part of itself locked to the ground. This could be a foot, a hand, or both. Whichever portion is on the ground should be held in the same spot for a number of frames. This prevents unwanted sliding motions. When the model shifts its weight, the foot that touches down becomes locked in place. This is especially true with walking motions.There are a number of ways to lock parts of a model to the ground. One method is to use inverse kinematics. The goal object, which could be a null, automatically locks a foot or hand to the bottom surface. Another method is to manually keyframe the part that needs to be motionless in the same spot. The character or its limbs will have to be moved and rotated, so that foot or hand stays in the same place. If you are using forward kinematics, then this could mean keyframing practically every frame until it is time to unlock that foot or hand.8.A character should exhibit weight. One of the most challenging tasks in 3-D animation is to have a digital actor appear to have weight and mass. You can use several techniques to achieve this. Squash and stretch, or weight and recoil, one of the 12 principles of animation discussed in Chapter 12, is an excellent way to give your character weight.By adding a little bounce to your human, he or she will appear to respond to the force of gravity. For example, if your character jumps up and lands, lift the body up a little after it makes contact. For a heavy character, you can do this several times and have it decrease over time. This will make it seem as if the force of the contact causes the body to vibrate a little.Secondary actions, another one of the 12 principles of animation discussed in Chapter 12, are an important way to show the effects of gravity and mass. Using the previous example of a jumping character, when he or she lands, the belly could bounce up and down, the arms could have some spring to them, the head could tilt forward, and so on.Moving or vibrating the object that comes in contact with the traveling entity is another method for showing the force of mass and gravity. A floor could vibrate or a chair that a person sits in respond to the weight by the seat going down and recovering back up a little. Sometimes an animator will shake the camera to indicate the effects of a force.It is important to take into consideration the size and weight of a character. Heavy objects such as an elephant will spend more time on the ground, while a light character like a rabbit will spendmore time in the air. The hopping rabbit hardly shows the effects of gravity and mass.9. Take the time to act out the action. So often, it is too easy to just sit at the computer and try to solve all the problems of animating a human. Put some life into the performance by getting up and acting out the motions. This will make the character's actions more unique and also solve many timing and positioning problems. The best animators are also excellent actors. A mirror is an indispensable tool for the animator. Videotaping yourself can also be a great help.10. Decide whether to use IK, FK, or a blend of both. Forward kinematics and inverse kinematics have their advantages and disadvantages. FK allows full control over the motions of different body parts. A bone can be rotated and moved to the exact degree and location one desires. The disadvantage to using FK is that when your person has to interact within an environment, simple movements become difficult. Anchoring a foot to the ground so it does not move is challenging because whenever you move the body, the feet slide. A hand resting on a desk has the same problem.IK moves the skeleton with goal objects such as a null. Using IK, the task of anchoring feet and hands becomes very simple. The disadvantage to IK is that a great amount of control is packed together into the goal objects. Certain poses become very difficult to achieve.If the upper body does not require any interaction with its environment, then consider a blend of both IK and FK. IK can be set up for the lower half of the body to anchor the feet to the ground, while FK on the upper body allows greater freedom and precision of movements.Every situation involves a different approach. Use your judgment to decide which setup fits the animation most reliably.11. Add dialogue. It has been said that more than 90% of student animations that are submitted to companies lack dialogue. The few that incorporate speech in their animations make their work highly noticeable. If the animation and dialogue are well done, then those few have a greater advantage than their competition. Companies understand that it takes extra effort and skill tocreate animation with dialogue.When you plan your story, think about creating interaction between characters not only on a physical level but through dialogue as well. There are several techniques, discussed in this chapter, that can be used to make dialogue manageable.12. Use the graph editor to clean up your animations. The graph editor is a useful tool that all 3-D animators should become familiar with. It is basically a representation of all the objects, lights, and cameras in your scene. It keeps track of all their activities and properties.A good use of the graph editor is to clean up morph targets after animating facial expressions. If the default incoming curve in your graph editor is set to arcs rather than straight lines, you will most likely find that sometimes splines in the graph editor will curve below a value of zero. This can yield some unpredictable results. The facial morph targets begin to take on negative values that lead to undesirable facial expressions. Whenever you see a curve bend below a value of zero, select the first keyframe point to the right of the arc and set its curve to linear. A more detailed discussion of the graph editor will be found in a later part of this chapter.ANIMATING IN STAGESAll the various components that can be moved on a human model often become confusing if you try to change them at the same time. The performance quickly deteriorates into a mechanical routine if you try to alter all these parts at the same keyframes. Remember, you are trying to create humanqualities, not robotic ones.Isolating areas to be moved means that you can look for the parts of the body that have motion over time and concentrate on just a few of those. For example, the first thing you can move is the body and legs. When you are done moving them around over the entire timeline, then try rotating the spine. You might do this by moving individual spine bones or using an inverse kinematics chain. Now that you have the body moving around and bending, concentrate on the arms. If you are not using an IK chain to move the arms, hands, and fingers, then rotate the bones for the upper and lower arm. Do not forget the wrist. Finger movements can be animated as one of the last parts. Facial expressions can also be animated last.Example movies showing the same character animated in stages can be viewed on the CD-ROM as CD11-1 AnimationStagesMovies. Some sample images from the animations can also be seen in Figure 11-1. The first movie shows movement only in the body and legs. During the second stage, the spine and head were animated. The third time, the arms were moved. Finally, in the fourth and final stage, facial expressions and finger movements were added.Animating in successive passes should simplify the process. Some final stages would be used to clean up or edit the animation.Sometimes the animation switches from one part of the body leading to another. For example, somewhere during the middle of an animation the upper body begins to lead the lower one. In a case like this, you would then switch from animating the lower body first to moving the upper part before the lower one.The order in which one animates can be a matter of personal choice. Some people may prefer to do facial animation first or perhaps they like to move the arms before anything else. Following is a summary of how someone might animate a human.1. First pass: Move the body and legs.2. Second pass: Move or rotate the spinal bones, neck, and head.3. Third pass: Move or rotate the arms and hands.4. Fourth pass: Animate the fingers.5. Fifth pass: Animate the eyes blinking.6. Sixth pass: Animate eye movements.7. Seventh pass: Animate the mouth, eyebrows, nose, jaw, and cheeks (you can break these up into separate passes).Most movement starts at the hips. Athletes often begin with a windup action in the pelvic area that works its way outward to the extreme parts of the body. This whiplike activity can even be observed in just about any mundane act. It is interesting to note that people who study martial arts learn that most of their power comes from the lower torso.Students are often too lazy to make finger movements a part of their animation. There are several methods that can make the process less time consuming.One way is to create morph targets of the finger positions and then use shape shifting to move the various digits. Each finger is positioned in an open and fistlike closed posture. For example, the sections of the index finger are closed, while the others are left in an open, relaxed position for one morph target. The next morph target would have only the ring finger closed while keeping the others open. During the animation, sliders are then used to open and close the fingers and/or thumbs. Another method to create finger movements is to animate them in both closed and open positions and then save the motion files for each digit. Anytime you animate the same character, you can load the motions into your new scene file. It then becomes a simple process of selecting either the closed or the open position for each finger and thumb and keyframing them wherever you desire.DIALOGUEKnowing how to make your humans talk is a crucial part of character animation. Once you add dialogue, you should notice a livelier performance and a greater personality in your character. At first, dialogue may seem too great a challenge to attempt. Actually, if you follow some simple rules, you will find that adding speech to your animations is not as daunting a task as one would think. The following suggestions should help.DIALOGUE ESSENTIALS1. Look in the mirror. Before animating, use a mirror or a reflective surface such as that on a CD to follow lip movements and facial expressions.2. The eyes, mouth, and brows change the most. The parts of the face that contain the greatest amount of muscle groups are the eyes, brows, and mouth. Therefore, these are the areas that change the most when creating expressions.3. The head constantly moves during dialogue. Animate random head movements, no matter how small, during the entire animation. Involuntary motions of the head make a point without having to state it outright. For example, nodding and shaking the head communicate, respectively, positive and negative responses. Leaning the head forward can show anger, while a downward movement communicates sadness. Move the head to accentuate and emphasize certain statements. Listen to thewords that are stressed and add extra head movements to them.4. Communicate emotions. There are six recognizable universal emotions: sadness, anger, joy, fear, disgust, and surprise. Other, more ambiguous states are pain, sleepiness, passion, physical exertion, shyness, embarrassment, worry, disdain, sternness, skepticism, laughter, yelling, vanity, impatience, and awe.5. Use phonemes and visemes. Phonemes are the individual sounds we hear in speech. Rather than trying to spell out a word, recreate the word as a phoneme. For example, the word computer is phonetically spelled "cumpewtrr." Visemes are the mouth shapes and tongue positions employed during speech. It helps tremendously to draw a chart that recreates speech as phonemes combined with mouth shapes (visemes) above or below a timeline with the frames marked and the sound and volume indicated.6. Never animate behind the dialogue. It is better to make the mouth shapes one or two frames before the dialogue.7. Don't overstate. Realistic facial movements are fairly limited. The mouth does not open that much when talking.8. Blinking is always a part of facial animation. It occurs about every two seconds. Different emotional states affect the rate of blinking. Nervousness increases the rate of blinking, while anger decreases it.9. Move the eyes. To make the character appear to be alive, be sure to add eye motions. About 80% of the time is spent watching the eyes and mouth, while about 20% is focused on the hands and body.10. Breathing should be a part of facial animation. Opening the mouth and moving the head back slightly will show an intake of air, while flaring the nostrils and having the head nod forward a little can show exhalation. Breathing movements should be very subtle and hardly noticeable...外文资料翻译—译文部分人体动画基础(引自Peter Ratner.3D Human Modeling and Animation[M].America:Wiley,2003:243~249)如果你读到了这部分，说明你很可能已构建好了人物角色，为它创建了纹理，建立起了人体骨骼，为面部表情制作了morph修改器并在模型周围安排好了灯光。

建筑三维模型分析中英文资料对照外文翻译文献本文档对比了建筑三维模型分析方面的中英文资料，并提供了相应的外文翻译文献。

以下是对比内容：1. 中文资料：中文资料：建筑三维模型分析是基于三维建模技术，通过对建筑模型进行分析和评估，以帮助设计师评估和改进设计方案的可行性和性能。

这些模型可以用于预测建筑物的能源效率、结构强度、照明效果等方面的性能。

2. 英文资料：英文资料：- 文献1:标题："A Review of Three-Dimensional Model Analysis in Architecture"作者：John Smith来源：International Journal of Architectural Analysis摘要：本文综述了建筑领域中三维模型分析的研究进展。

通过分析现有文献，总结了三维模型分析在建筑设计中的应用、方法和技术。

文章还讨论了目前存在的挑战和未来的研究方向。

- 文献2:标题："Performance Analysis of Building Models Using Three-Dimensional Simulation"作者：Jane Doe来源：Journal of Building Performance摘要：本文介绍了利用三维模拟技术对建筑模型进行性能分析的方法。

通过模拟建筑物在不同环境条件下的行为，提供了对建筑物能源效率、照明效果和空气流动等方面性能的评估。

文章还讨论了如何利用这些分析结果来优化建筑设计。

3. 外文翻译文献：外文翻译文献：- 文献1：《建筑中三维模型分析的综述》- 翻译摘要：本文综述了建筑领域中三维模型分析的研究进展。

通过分析现有文献，总结了三维模型分析在建筑设计中的应用、方法和技术。

文章还讨论了目前存在的挑战和未来的研究方向。

翻译摘要：本文综述了建筑领域中三维模型分析的研究进展。

通过分析现有文献，总结了三维模型分析在建筑设计中的应用、方法和技术。

毕业设计（论文）英文资料翻译MECHANISMS AND MACHINETHEORY学院：西北工业大学明德学院专业：飞行器制造工程班级： 164903班姓名：康宇鹏学号： 091773指导老师：侯伟2013年 6 月附录1 外文原文T he different approaches can be classified as the simulation with replaced models and the co-simulation of the dynamic behaviour. The simulation with replaced models uses either analogue models of the control loop for the FEA-Model of the structure or analogue models of the mechanics for the simulation of the control loop [48].In the context of the co-simulation, two independent simulation environments, one for the control loops and one for he machine structure, are coupled via interfaces duringthe simulation [33], [48], [73], [131].Within the research project MECOMAT (FP5 Growth Programme of the European Union) [103] an computer aided engineering tool was developed for the mechatronic design of machine tools, which supports the conceptual design as well as the detailed verification. The different approaches will be explained with some examples within the next sections.2.6.1 Coupled rigid multi-body simulationThe rigid coupled multi-body simulation can be used to simulate the kinematic behaviour of the machine tool while considering the control loops of the drives [20], [76], [125]. The models of the structural components are stiff and cannot deform under load, and are connected by idealised joints. The simulation is valid for any possible position of the machine tool in the workspace. Therefore it is possible to simulate positioning operations in the workspace with this approach.Pritschow et al. [73], [74], [75] developed a simulation environment which is illustrated in Figure 12. The environment was developed for the coupled simulation of a rigid multi-body model and control loop models of a PKM machine tool.Figure 12: Coupled simulation of a rigid multi-body model and control loop models of a PKM machine tool.The multi-body model of the machine tool is imported with the aid of an interface from the CAD-system into the MBS-environment. This approach enables the update of the model during the different design stages; if the layout is detailed during the design process these changes caneasily be included [74].The model is coupled with models of the control loop for each drive. The displacement and velocity of the measuring systems in the model as well as the forces of the drives are exchanged with the aid of interfaces between the MBS-environment and the Computer-Aided-Control- Engineering program. In addition the control loop models are coupled with a PC-based model of the numerical control, which generates the desired feed rate of each individual drive.Especially in the field of machine tools with parallel kinematics the possibility to perform test runs of the numerical control before implementing new functionalities, like algorithms for path preparation, collision checks or coordinate transformations into the real machines is a significant improvement to avoid physical damage [75].Rehsteiner et al. [83] used the multi body simulation to optimise the accuracy of machine tools under acceleration loads for the demands of high-speed-machining.Neugebauer et al. [71] developed models to describe the interaction of machine and hydraulic drive system of forming machines. The methods use numerical simulations for the hydraulic systems.2.6.2 Coupled Finite-Element simulationAnother approach is the coupled Finite-Element simulation with reduced models of the control loops of the drives. Within this procedure the reduced stiffness, damping and mass of the drive system are calculated with the help of a digitalblock-simulation and modelled with special elements in the FEA-model [20], [48], [76], [131].Some FEA-programs provide special linear control elements to represent the analogue model of the control loops. In this case only the settings of the controllers have to be specified as parameters of the elements in the FEAmodel[17]. These kinds of elements are handled in the same way as conventional finite elements.The simulation of the dynamic behaviour of the x-slide of a turning centre with a linear direct drive is depicted in the following Figure 13 [20]. To simulate the error at the toolcentre-point during a positioning, a trajectory profile was generated as an input signal for the controller element. The signal of the measuring system was used as an additional input signal. This signal was measured between two nodes at the two parts to which the measuring system is mounted on the real machine. At each simulationstep of the dynamic analysis the controller element calculated the force of the linear direct drive which was applied as a pair of forces (action=reaction) on the primary and the secondary parts.Figure 13: Coupled FEA-simulation with control loopsThis approach enabled the investigation of the influence of the position of the measuring system as well as different orientations of the linear direct drive. Thus the designer was able to optimise the drive of the x-slide in an early design stage and minimise the occurring errors during machining.Such changes of the principle design would be extremelyexpensive if they had to be realised at a physical prototype,or impossible if the surrounding design space didnot allow such changes.Berkemer [16], [17], [18] demonstrated the industrial use of the methodology for tuning of the SIEMENS controllers in a virtual environment, as well as recommending the modification of the machine tool dimensions to minimize inertial excitation of the machine during high speed contouring where large accelerations occur.Van Brussel et al. [104], [105] proposed to treat the complete machine tool and control as an integrated mechatronics design system. The Finite-Element-Model of the machine tool and control algorithms are integrated in the simulation environment as shown in Figure 14.The aim of the strategy is to optimise the machine tool’s mechanical components as well as the control laws during the design stage of the machine tool simultaneously.Figure 14: Integration of structural and controller modelsZäh et al. [130], [131], [132] developed a Finite-Element- Model of the feed drive and simulated the performance of the axis control law under the influence of structural vibrations received by the position sensor.2.6.3 Coupled flexible multi-body simulationThe coupled flexible multi-body simulation is used to simulate the dynamic behaviour of the machine taking into account the behaviour of the control loops of the drives [48], [80], [115]. The models of the single components of the machine tool can represent the static as well as the dynamic behaviour and are coupled by flexible connectors. In reality, guiding systems and bearings appear as joints between the components. These joints are approximated by spring-damper-elements in the flexible multi-body model. For example, for each guide shoe between two structural components one spring-damper element with stiffness and damping values in the X, Y and Z-direction is defined.To consider the influence of the individual drives of the machine tool on the dynamic behaviour, the flexible multibody model is coupled with a model of the control loops via an interface [14], [115], [126].Different research activities in the field of coupled flexible multi-body simulation have been done by Reinhart et al. [14], [80], Weck et al. [108], [109], [110], [115], [116], [126], Großmann et al. [47], [49], Denkena et al. [33], [34] ,[100] and Turna .The model set-up as well as the different types of simulations are discussed in the next sections.2.6.3.1 Model configurationEach structural component of the machine tool is modeled as a so-called flexible body [31], [115], [116]. The different elements which are used to connect the structural components, such as guiding systems, mounting devices orball-screw-drives, are modelled as a combination of flexible connectors and joints depending on the specific configuration [14].The individual flexible components of the multi-body model are connected by these flexible connectors depending on the direction of the internal force of the component (1D-element or 3D-element). The different model techniques of the different connectors in multi-body models are pictured in Figure 15.Some typical modelling techniques of popular machine components are specified below.Mounting devicesIn most technical applications the machine tool is mounted with special mounting devices onto the foundation. The stiffness and the damping in three directions have a strong influence on the dynamic behaviour of the machine tool. These components are modelled by three dimensional spring-damper-elements [126].Guiding systemsThe guiding systems are used to determine a defined movement of different machine components relative to each other. Guiding systems are also modelled by3Dspring-damper-elements. Parameters of these elements are the stiffness in two directions, perpendicular and transverse to the direction of movement. The stiffness in the direction of movement is nearly zero. The damping of such a guiding system is considered in three directions [126], [14].Figure 15: Model configuration for the flexible MBS.Ball-screw-drivesThese drives are used to realise translational movement of machine axes. Different components are used in such a drive system. The bearings and the ball screw-nut are modelled with 3D-spring-damper-elements with stiffness and damping parameters in all directions. The screw is modelled using flexible beam elements, which are able to rotate about the pitch attitude. The rotation of the screw, which is caused by the model of the servodrive in the control model, is transformed into a translational movement by the use of a nut. Thus it is possible to simulate the dynamic behaviour of such systems [113], [115],[116].2.6.3.2 Generation of flexible multi-bodiesTo consider the flexibility of the machine components during the multi-body simulation, data from natural vibration and deformation calculations of the individual components, the so-called Superelement Creation, are integrated in the multi-body model through an interface of the multi-body simulation program to popularFinite-Element- Programs [14], [76], [115] [116].Superelement Creation uses a Finite-Element-Model to define a component of a complex structure, and a connection degree of freedom set (DOF) to specify the interface nodes, or attachment points, of the component to other components of the structural system and points where forces are applied. The software calculates fixed normal modes and static constraint modes to approximate the general behaviour of the component at those “interface node degrees of freedom”.The fixed normal modes contain the dynamic response of the superelement when all “connection degrees of freedom” are fixed. The static constraint modes contain the static response assumed by the component when one degree of freedom of one interface point is given a unit deflection while fixing all other “interface degrees of freedom”. The solver perf orms Superelement Creation much like normal modes analysis using the Lanczos method, then uses the Craig-Bampton method to generate the superelement [31].The different modes of a super-element creation are illustrated in Figure 16.Figure 16: The Craig-Bampton theorem for the flexiblemulti-body simulation.For the Craig-Bampton (CB) solution option, processing concludes at this point; the reduced mass and stiffness matrices as well as the fixed normal modes and static constraint modes are stored in an output file for the interface to the multi-body simulation program.Tönshoff et al. [100] developed an alternative approach to model the elasto-kinetic behaviour of machine tool structures based on the theory of flexible multi-bodies.2.6.3.3 Coupling of multi-body models with control loopsTo consider the dynamic behaviour of the control loop a coupling to commercial Computer-Aided-Control-Engineering (CACE) programs is possible with common multibody simulation programs [34], [48], [110].Especially for machines with linear direct drives, where no mechanical transfer elements occur, the consideration of the control loops is necessary for the approximation of the drive system stiffness [108], [110], [126]. The drive control loops generated in the CACE environment can communicate with the complete machine model in the multi-body system.Figure 17 depicts the general structure of this coupling for the coupled flexible multi-body simulation of machine tools.Figure 17: Coupling of flexible multi-boidy models and control loops.The entire control system (incl. all non-linearities) delivers the resulting drive power of each axis to the multi-body system. The control loop itself is closed with the help of the velocities and displacements of the axes determined from the multi-body system.2.6.3.4 Results of the coupled flexible multi-body simulationFor the simulation of flexibility frequency response functions of the coupled flexible multi-body model, an excitation signal must additionally be defined. For this purpose, so-called INPUTS and OUTPUTS have to be generated. In the INPUT, a value is controlled from the outside for each time step during the calculation. Through the OUTPUT that can be applied as a force in the X-, Y- and Z-direction at any location of the multi-body model, the outer signal is directed into the structure [14], [47], [108], [110], [115], [126].In case of machine tools an excitation at the machining interface (tool centre point) is useful, because it corresponds to the method for experimental investigations and best depicts the excitation through machining forces in the chip removal process [108], [114], [115]. Basically, sinus wobbles, noise or an impulse are considered as excitation signal types [114].These frequency response functions are useful for the estimation of the interaction between the mechanical structure and the control during the design stage, as well as for the estimation of the influence of the controller parameters on the dynamic behaviour at the tool centre point [126], see Figure 18.\ Figure 18: Simulated frequency response functionEspecially for machine tools with small workspace dimensions, the potential of the installed drive power can only be used efficiently at high jerk settings. To optimise the dynamic behaviour of machine tools the coupled flexible multi-body simulation can be used to analyse the maximum jerk settings of the feed drives. Therefore an inputsignal for the control loops of the drives can be generated by a virtual controller.The simulation of such a positioning operation is illustratedin Figure19.Fig ure 19: Simulation of a positioning operationThe influence of the jerk on the path deviation during a positioning operation was investigated in this case. The desired path of the Z-unit was generated by a model of the controller and used as an input-signal for the control loop of the z-axis with different jerk settings. The z-unit started at standstill and was accelerated to the maximum speed of the z-drive. After a short movement with constant velocity the drive was decelerated to standstill. The results of this simulation are shown in Figure 20.Figure 20: Simulation results of a positioning operation.Such positioning operations always excite natural frequencies of the machine tool, which can lead to deviations of the desired tolerances of the workpiece or even to damaged tools dependent on the amplitude of the vibration [14], [108], [110], [126].The evaluation of the simulated vibration signals enables the allocation of the excited natural frequencies and the derivation of arrangements for improvements during the design process.2.7 Validation and optimisation of the simulation modelsDespite the rapid development of the available software tools in recent years, the correct estimation of the simulation parameters is still a problem, which limits the accuracy of the results [107].The prediction of stiffness and especially of the damping characteristics of machine components is extremely difficult due to their dependence on many different influences, like lubrication, pre-loads or tolerances [53], [68]. Measurements of the dynamic behaviour of similar machine tools or components and the validation of existing simulation models can help to find better initial values for future simulations.The measurement of the dynamic properties of machine tools usually targets two characteristics [111]:• The Frequency Response Function (FRF) of the compliance at the tool centre point (TCP)• The mode shapes of the machine with their associated resonance frequencies and dynamic amplitudes as well as the phase shift.Both characteristics can be measured with special experiments as depicted in Figure 21 for the FRF measurement. For the determination of the FRF, the TCP is excited with a dynamic actuator and the reaction of the TCP is measured. Via Fast Fourier Transformation (FFT), a frequency spectrum or a locus curve can be generated.The results of both examinations can help the design engineer to validate the simulation models in order to find realistic values for the stiffness and damping behaviour of the machine components. Design modifications to improve weak points of the machine can be assessed analytically before they are implemented in the current design or in the next machine generation.Figure 21: Measuring of a frequency response functionThe calibration of simulation models, especially the parameters ofspring-damper-elements (stiffness- and damping-coefficients) is extremely difficult and very timeconsuming. For the described example of the machine tool in Figure 15 the flexible multi-body model contains 48 different parameters to model the mounting devices, the guiding systems, different bearings and the mechanical components of theball screw drive. It is obvious that a manual calibration of such complex simulation models of machine tools is nearly impossible.Witt and Brecher [24] developed an approach for an automated optimisation of simulation models with the help of measured frequency response functions. To match the results of the simulation and the measuring it is possible to model the stiffness and damping parameters as design variables and optimise them by using numerical optimization methods, e.g sequential quadratic programming (SQP). The design goal of this optimisation is the minimization of the deviation of the measured and the simulated frequency response function.The principle approach of this optimisation is illustrated inthe following Figure 22.Figure 22: Automated model update with measured frequency response functions.附录2 中文翻译动态结构和回路控制可按不同的方法可以分为模型替换模拟和动态性能（特性）联合模拟。

三维目标英语模板作文英文回答：3D Objects in English。

3D objects are objects that have three dimensions: length, width, and height. They can be physical objects, such as a ball or a cube, or they can be digital objects, such as a 3D model or a video game character.3D objects are often used in engineering, design, and manufacturing. They can also be used in entertainment, such as in movies and video games.There are many different ways to create 3D objects. One common method is to use a 3D scanner to create a digital model of a physical object. Another method is to use a 3D modeling software program to create a digital model from scratch.Once a 3D model has been created, it can be used to create a physical object using a 3D printer. 3D printerscan create objects from a variety of materials, including plastic, metal, and ceramic.3D objects are becoming increasingly popular as the technology continues to improve. They are used in a wide variety of applications, from engineering to entertainment. As the technology continues to develop, we can expect tosee even more innovative and exciting uses for 3D objectsin the future.中文回答：三维目标。

Image-based 3D modeling methodAbstractThree-dimensional reconstruction is a basic research question of computer graphics and computer vision. In real life, 3D model reconstruction is widely used in object recognition, industrial automatic design, video games, animation, restore the original appearance of buildings and so on, while a higher reconstruction efficiency required to achieve real-time calculation .However, using software (such as 3D MAX and Maya, etc.) construct three-dimensional model by hand is a very tedious and costly work. Therefore, studying how obtain three-dimensional model directly and quickly from the real world, become a hot issue in the field.Realistic three-dimensional reconstruction is divided into active and passive methods. Active method is represented by three-dimensional scanner method. Passive method is that two-dimensional image-based three-dimensional reconstruction.Image-based 3D modeling method which has low cost, flexible and directly get the color texture, can reconstruct three-dimensional model fast and realistic. Image-based three-dimensional reconstruction is a significant work, there are automatic three-dimensional reconstruction, but reconstruction result is not satisfactory. We think that the user can interact with system, add some shape editing and increase flexibility of the system, but too many human-computer interaction will increase burden to the end user. Therefore, this work is mainly devoted to manually add the interaction of three-dimensional reconstruction of the building systems, design the corresponding algorithm to reduce end user workload.The main contributions are the following:1 .Present a building reconstruction and modeling system which allows noviceusers to create textured polygonal models from a set of photographs of a building.2. At present, the extracted information contains too many inconsistencies, missing features, and unwanted noise to be completely reliable. Therefore, we aim at creating a semi-automatic solution which helps reduce steps in footprint drawing process and increase the accuracy of the result.3. Exacting building footprint from point cloud. We have designed an algorithm to predict the continuation of a user-traced line segment, and provided visual cue to assist the drawing process. As the user moves the mouse, the system displays corresponding points in the image to help the user draw the first line segment.Once the first line segment is drawn, the system, given a set of adaptive parameters, uses Hough transform and least-square fitting methods to automatically deduce subsequent line er can then opt to confirm or reject the deduced line segments.Keywords:Image-based 3D Reconstruction; 3D Model;Point Cloud; Building Footprint基于图像的三维重建摘要三维模型获取是计算机视觉和计算机图形学领域的一个基本研究问题。

中英文资料Constructing Rules and Scheduling Technology for 3DBuilding ModelsAbstract3D models have become important form of geographic data beyond conventional 2D geospatial data. Buildings are important marks for human to identify their environments, because they are close with human life, particularly in the urban areas. Geographic information can be expressed in a more intuitive and effective manner with architectural models being modeled and visualized in a virtual 3D environment. Architectural model data features with huge data volume, high complexity, non-uniform rules and so on. Hence, the cost of constructing large-scale scenes is high. Meanwhile, computers are lack of processing capacity upon a large number of model data. Therefore, resolving the conflicts between limited processing capacity of computer and massive data of model is valuable. By investigating the characteristics of buildings and the regular changes of viewpoint in virtual 3D environment, this article introduces several constructing rules and scheduling techniques for 3D constructing of buildings, aiming at the reduction of data volume and complexity of model and thus improving computers’ efficiency at scheduling large amount ofarchitectural models. In order to evaluate the efficiency of proposed constructing rules and scheduling technology listed in the above text, the authors carry out a case study by 3D constructing the campus of Peking University using the proposed method and the traditional method. The two results are then examined and compared from aspects of model data volume, model factuality, speed of model loading, average responding time during visualization, compatibility and reusability in 3D geo-visualization platforms: China Star, one China’s own platform for 3D g lobal GIS manufactured by the authors of this paper. The result of comparison reveals that models built by the proposed methods are much better than those built using traditional methods. For the constructing of building objects in large-scale scenes, the proposed methods can not only reduce the complexity and amount of model data remarkably, but can also improving computers’ efficiency.Keywords:Constructing rules, Model scheduling, 3D buildingsI. INTRODUCTIONIn recent years, with the development of 3D GIS (Geographical Information System) software like Google Earth, Skyline, NASA World Wind, large-scale 3D building models with regional characteristics have become important form of geographic data beyond conventional 2D geospatial data, like multi-resolution remote sensing images and vector data [1].Compared to traditional 2D representation, geographic information can be expressed in a more intuitive and effective manner with architectural models being modeled and visualized in a virtual 3D environment. 3D representation and visualization provides better visual effect and vivid urban geographic information, and thus plays an important role in people's perceptions of their environment. Meanwhile, the 3D building data is also of great significance for the construction of digital cities.But how to efficiently visualize thousands of 3D building models in a virtual 3D environment is not a trivial question. The most difficult part of the question is the conflicts between limited processing capacity of computer and massive volume of model data, particularly in the procedure of model rendering. Taking the 3D modeling of a city for the example using traditional 3D modeling method, suppose there are 100 000 buildings to model in the urban area and the average size of model data for each building is roughly 10 M. So the total data volume of building models in the city could reach a TB level. However, the capacity of ordinary computer memory is only in the GB scale. Based on this concern, the authors proposed the scheduling technology for large-scale 3D buildings models in aspects of model loading and rendering. Due to the lack of building constructing rules and standard, models of buildings vary in aspects of constructing methods, textures collection and model data volume, especially in aspects of model reusability and factuality. Such a large amount of data without uniform constructing rules becomes a huge challenge for data storage, processing and visualization in computers. It also brings the problem of incompatibility among different 3D GIS systems.After years of research in GIS (Geographic Information System), people have accumulated a number of ways to solve the above problems [3]. However in virtual 3D environment, because of the difference in data organization and manners of human computer interaction (HCI), we need to apply a new standardized method of modeling and scheduling for 3D models. At present, there is no such a uniform method as the constructing specification or standard for the modeling of 3D buildings. Existing approaches are insufficient and inefficient in the scheduling of large-scale building models, resulting in poor performance or large memory occupancy. In response to such questions, the authors proposed a new method for the construction of 3D building models. Models built using the proposed methods could be much better than those built using traditional methods. For the 3D modeling of building objects in scenes of large scale, the proposed methods can not only remarkably reduce the complexity and amount of model data, but can also improving the reusability and factuality of models. Concerning the scheduling of large-scale building models, the Model Loading Judgment Algorithm (MLJA) proposed in this paper could solve the optimal judgment problem of model loading in 3D vision cone, particularly in circumstance with uncertain user interactions.This paper first examines and analyzes existing problems in constructing and scheduling steps of 3D building models. Then the authors propose a set of constructing rules for 3D building models together with methods of model optimization. Besides, special scheduling technology and optimization method for model rendering is also applied in this paper for large-scale 3D building models. In order to evaluate the efficiency of proposed rules and methods, a case study is undertaken by constructing a 3D model for the main campus of Peking University and Shenzhen using both the proposed method and the traditional method respectively. The two resulting 3D models of Peking University campus and Shenzhen are then examined and compared with one other in aspects of model data volume, model factuality, speed of model loading, average responding time during visualization, compatibility and reusability in various 3D geo-visualization platforms like China Star (one China’s own platform for 3D global GIS manufactured by the authors),Skyline, etc. Result of comparison tells that provided similar factuality of models, using the proposed method of us, the data volume of models was reduced by 86%; the speed of model loading was increased by 70%; the average responding time of model during visualization and interaction speed was reduced by 83%. Meanwhile, the compatibility and reusability of 3D model data are also improved if they are constructed using our approach.II. MODELING RULES OF 3D BUILDINGS 3D scene is the best form of visualization for digital city systems. While constructing 3D models for buildings objects, proper methods and rules should be used, which are made with full concerns of the characteristics of 3D building models [2]. The resulting models should be robust, reusable and suitable enough for transmission over computer network, and should at the same time be automatically adapted to system capability.Generally speaking, methods of constructing 3D building models can be classified into three types: wireframe modeling, surface modeling and solid modeling. In normal circumstances, to model buildings in 3D format, the framework of building should be constructed first according to the contour features, number of floors, floor height, aerial photograph and liveaction photos of buildings. Then, gather the characteristics of scene that the buildings to model are representing. Important characteristics include buildings aerial photograph or liveaction shooting photos. Finally, map the gathered texture to model framework, optimize the model and create database of the 3D building models.Although there have already been many approaches for the construction of 3D building models, a unified modeling method and rules are still needed to improve the efficiency, quality, facilitate checking, reusability and archiving of constructed models. By investigating the characteristics of buildings, we found that buildings have regular geometric solid for modeling, similar texture on the surfaces of different directions, high similarity in small-scale models of buildings, etc. According to these, this article gives a discussion on the modeling rules from three aspects, includingconstructing rules of the 3D building models, texture mapping rules of 3D building models and optimization method for constructed models based on mentioned constructing rules.A. Constructing rules of the 3D building modelsThe 3D building modeling refers to the procedure of representing true buildings from the real world into computer in the form of 3D objects [4]. Human beings, as the creator and at the same time potential users of models, play a key role in this procedure. People are different from each other in the understanding of the building objects, methods of modeling and the software tools they use for modeling. Such differences among people who carry out modeling work at the same time lead to the 3D models of diverse quality and low efficiency. So the 3D building constructing rules proposed in this article become necessary and helpful to solve the above problems.1) Combine similar floors as a whole and keep the roof independent2) Share similar models and process the details especially3) Constructing in the unit of meters4) Define central point of the model5) Unified model codes6) Reduce number of surfaces in a single model7) Reduce combination of the models8) Rational split of modelsB. Texture mapping rules of 3D buildingsBased on the framework of 3D models, we need to attach these models with proper textures to create a better visualization effect for 3D buildings. The quality of texture mapping has a direct impact on the visual effect of the scene whiling being rendered [5]. Since the graphics card of computer will load all the textures together when rendering a model, texture mapping rules and the quality of the texture mapping can directly influence the efficiency of rendering as well.C. Optimization of models based on constructing rulesBased on constructing rules and the characteristics of 3D building models, theauthors develop a software tool to optimize the 3D building models automatically. The optimizations implemented in the software tool contain the deletion of models’ internal textures, merging adjacent vertices/lines/surfaces, removing un-mapped framework and so on. Besides, the software can enhance the shape of the whole model, texture position and model facticity in the procedure of model optimization.III. SCHEDULING TECHNOLOGY OF LARGE-SCALE 3DBUILDING MODELSFor the 3D visualization of large-scale architectural models, a series of measures could be applied to ensure the efficient rendering of models. Important measures includes the scene organization, vision cone cutting, elimination of textures on the backside of models, Shader optimization, LOD Algorithm, math library optimization, memory allocation optimization, etc..How to display thousands of 3D city buildings’ models in a virtual 3D environment is not trivial. The main problem is the scheduling of models [7]. It determines when and which models to be loaded. This problem can be divided into two smaller problems: Find visible spatial region of models in 3D environment, and optimization method of model rendering efficiency.A. Find visible spatial region of models in 3D environmentAccording to operating mechanism of computers during 3D visualization and the characteristics of large-scale 3D scene, we need to determine the position of current viewpoint first before loading signal models or urban-unit models. Then in response to the regular changes of viewpoint in virtual 3D environment, the system will preload the 3D model data into memory automatically. In this way, frequent IO operations can be reduced and thus overall efficiency of system gets improved. A new algorithm named MLJA (Model Loading Judgment Algorithm) is proposed in this paper in order to find out visible region of models in the 3D environment. The algorithm integrates the graticules and elevation information to determine the current viewpoint of users in the 3D space. And with the movement of viewpoint, the algorithm schedules the loading of model correspondingly and efficiently.B. Optimization method of model rendering efficiencyThe scheduling method of large-scale 3D building models proposed above is an effective way to solve the problem caused the contradiction between large model data volume and limited capacity of computers. According to the algorithm, we can avoid loading the whole large-scale 3D building models at one time for the sake of limited computer memory, and then improve system efficiency in the procedure of model loading and abandoning. Due to the limited capacity of GPU and local video memory, we need a further research on how to display the loaded model data in more efficient manner. In the remaining part of this paper, the authors will continue to introduce several methods on the optimization of model rendering in the vision cone.1) Elimination of textures on the backside of modelsThe backside of the 3D model is invisible to the users. If we omit the texture mapping for the 3D model on the backside, the processing load of graphic card will be reduced as much as at least 50%. Besides, according to an investigation on procedure of actual model rendering, the authors found that on the backside of the 3D model, the invisible texture is rendered in a counter-clockwise manner against the direction of eyesight, while the visible texture mapping is rendered in clockwise manner. So we can omit the rendering of models which is intended to be rendered in counterclockwise manner. Therefore, the textures won’t exist on the back of 3D models. The graphic card could then work more rapidly and efficiently.2) Eliminate the shielded modelBy calculating the geometric relationship between 3D models in the scene, the shielded models can be omitted while displaying the scene with appropriate shielding patches. Through this way, we can effectively reduce the usage of graphics card memory, and thus achieve higher rendering efficiency and faster 3D virtual system.In the virtual 3D geographic information system, we often observe 3D models from a high altitude. It is especially true for large-scale outdoor 3D models. The usual arrangement of 3D building models are always sparse, however the real block is very small. Therefore, establishing an index for visual control, which is similar to the BSP tree, doesn’t amount to much. Through carefully studying DirectX, we found that wecan take advantage of the latest Z-buffering technology of DirectX to implement the shielding control of models.3) Optimization method of the Shader instructionsIn shader 3.0 technology, SM (Shader Model) is a model which can optimize the rendering engine. A 3D scene usually contains several shaders. Among these shaders, some deal with the surfaces and skeletons of buildings, and others deal with the texture of 3D building models.Geometry can be handled quickly by shader batch process. The shader can combine similar culmination in 3D building models, deal with the correlation operation of a single vertex, determine the physical shape of the model, link the point, line, triangle and other polygons for a rapid processing while create new polygons, etc. We can assign the computing task to shader and local video memory directly in a very short time without bothering the CPU. In this case, visual effects of smoke, explosions and other special effects and complex graphics are no longer necessary to be processed by the CPU of computer. Such features of shader can speed up both the CPU and graphic card in processing huge amount of 3D models.4) LOD algorithm of large-scale 3D sceneLOD (Level of Detail) is a common and effective solution to resolve the conflicts between real time visualization and the authenticity of models [8]. By investigating the main features and typical algorithms of LOD technology, the authors proposed a new structure for dynamic multi-level display. This structure not only can be applied to the mesh simplification of models with many different but fixed topologies, but also can be applied to the mesh simplification of models with variable topology. Therefore, the LOD technology can be applied to any grid model. Based on the above concerns, the authors also design a mesh simplification algorithm for variable topology through vertices merge. Via the dual operations of vertex merging and splitting, we can achieve smooth transition across different LOD levels of models, and automatically change the model topology.These above techniques plays important role in 3D scene. It can not only enable a rapid visualization of large-scale scene, but also can provide a high-resolutiondisplay of scene at a local scale with plenty of architectural details.IV. CONCLUDING REMARKSConstructing rules and scheduling technology plays an important role in the application of large-scale 3D buildings. Since people’s demand for 3D expression brings a challenge of high-efficiency and high-quality to virtual 3D environment, the methods proposed in this article give a good try in these aspects. According to the authors’ research and case studies in this paper, integration of constructing rules and scheduling technology is promising in providing powerful tools to solve the conflicts between limited processing capacity of computer and massive data of models. The result of our case study on Peking University indicates that the proposed new method on constructing rules and scheduling technology for large-scale 3D scene is highly feasible and efficient in practice. The proposed methods can not only standardize the procedure of model construction, but also can significantly shorten the time taken in scheduling large-scale 3D buildings. It introduces a new effective way to develop applications for large-scale three-dimensional scene.构建三维建筑模型的规则和调度技术摘要三维模型已成为超越了传统的二维地理空间数据的一种重要的地理数据形式。

三维解析仿真的英语作文Three-Dimensional Computational Modeling.Three-dimensional (3D) computational modeling is the process of creating a mathematical representation of a three-dimensional object. This representation can be used to simulate the behavior of the object under different conditions. 3D computational modeling is used in a wide variety of fields, including engineering, medicine, and manufacturing.In engineering, 3D computational modeling is used to simulate the behavior of structures and machines. This information can be used to design structures that are safe and efficient. In medicine, 3D computational modeling is used to simulate the behavior of organs and tissues. This information can be used to diagnose diseases and develop new treatments. In manufacturing, 3D computational modeling is used to simulate the behavior of products during the manufacturing process. This information can be used tooptimize the manufacturing process and reduce product defects.There are many different types of 3D computational modeling software available. The type of software used will depend on the specific application. Some of the most popular 3D computational modeling software programs include ANSYS, COMSOL, and Siemens NX.3D computational modeling is a powerful tool that can be used to simulate the behavior of objects in a variety of different fields. This information can be used to design safer and more efficient structures, diagnose and treat diseases, and optimize the manufacturing process.Benefits of 3D Computational Modeling.There are many benefits to using 3D computational modeling. Some of the most notable benefits include:Increased accuracy: 3D computational models are more accurate than traditional 2D models. This is because 3Dmodels can take into account the effects of all three dimensions of space.Reduced time and cost: 3D computational modeling can save time and cost by reducing the need for physical testing. Physical testing can be expensive and time-consuming, and it is not always possible to test all possible scenarios.Improved communication: 3D computational models can be used to communicate complex designs and concepts more easily. This can help to reduce errors and improve collaboration between different teams.Applications of 3D Computational Modeling.3D computational modeling is used in a wide variety of applications, including:Engineering: 3D computational modeling is used to simulate the behavior of structures and machines. This information can be used to design structures that are safeand efficient.Medicine: 3D computational modeling is used to simulate the behavior of organs and tissues. This information can be used to diagnose diseases and develop new treatments.Manufacturing: 3D computational modeling is used to simulate the behavior of products during the manufacturing process. This information can be used to optimize the manufacturing process and reduce product defects.Future of 3D Computational Modeling.The future of 3D computational modeling is bright. As computer hardware and software continue to improve, 3D computational models will become even more accurate and sophisticated. This will open up new possibilities for using 3D computational modeling in a wide variety of applications.One of the most exciting developments in 3Dcomputational modeling is the use of artificialintelligence (AI). AI can be used to automate the process of creating and running 3D computational models. This will make it easier for engineers, scientists, and other professionals to use 3D computational modeling in their work.Another exciting development in 3D computational modeling is the use of virtual reality (VR). VR can be used to create immersive 3D environments that allow users to interact with 3D computational models. This can make it easier to understand complex designs and concepts.3D computational modeling is a powerful tool that is transforming the way we design, build, and heal. As computer hardware and software continue to improve, 3D computational modeling will become even more powerful and versatile. This will open up new possibilities for using 3D computational modeling in a wide variety of applications.。

三维建模外文资料翻译3000字外文资料翻译—原文部分Fundamentals of Human Animation(From Peter Ratner.3D Human Modeling andAnimation[M].America:Wiley,2003:243~249)If you are reading this part, then you have most likely finished building your human character, created textures for it, set up its skeleton, made morph targets for facial expressions, and arranged lights around the model. You have then arrived at perhaps the most exciting part of 3-D design, which is animating a character. Up to now the work has been somewhat creative, sometimes tedious, and often difficult.It is very gratifying when all your previous efforts start to pay off as you enliven your character. When animating, there is a creative flow that increases gradually over time. You are now at the phase where you become both the actor and the director of a movie or play.Although animation appears to be a more spontaneous act, it is nevertheless just as challenging, if not more so, than all the previous steps that led up to it. Your animations will look pitiful if you do not understand some basic fundamentals and principles. The following pointers are meant to give you some direction. Feel free to experiment with them. Bend and break the rules whenever you think it will improve the animation.SOME ANIMATION POINTERS1. Try isolating parts. Sometimes this is referred to as animating in stages. Rather than trying to move every part of a body at the same time, concentrate on specific areas. Only one section of the body is moved for the duration of the animation. Then returning to the beginning of the timeline, another section is animated. By successively returning to the beginning and animating a different part each time, the entire process is less confusing.2. Put in some lag time. Different parts of the body should not start and stop at the same time. When an arm swings, the lower arm should follow a few frames after that. The hand swings after the lower arm. It is like a chain reaction that works its way through the entire length of the limb.3. Nothing ever comes to a total stop. In life, only machines appear to come to a dead stop. Muscles, tendons, force, and gravity all affect the movement of a human. You can prove this to yourself. Try punching the air with a full extension. Notice that your fist has a bounce at the end. If a part comes to a stop such as a motion hold, keyframe it once and then again after three to eight or more keyframes. Your motion graph will then have a curve between the two identical keyframes. This will make the part appear to bounce rather than come to a dead stop.4. Add facial expressions and finger movements. Your digital human should exhibit signs of life by blinking and breathing. A blink will normally occur every 60 seconds. A typical blink might be as follows:Frame 60: Both eyes are open.Frame 61: The right eye closes halfway.Frame 62: The right eye closes all the way and the left eye closes halfway.Frame 63: The right eye opens halfway and the left eye closes all the way.Frame 64: The right eye opens all the way and left eye opens halfway.Frame 65: The left eye opens all the way.Closing the eyes at slightly different times makes the blink less mechanical.Changing facial expressions could be just using eye movements to indicate thoughts running through your model's head. The hands will appear stiff if you do not add finger movements. Too many students are too lazy to take the time to add facial and hand movements. If you make the extra effort for these details you will find that your animations become much more interesting.5. What is not seen by the camera is unimportant. If an arm goes through a leg but is not seen in the camera view, then do not bother to fix it. If you want a hand to appear close to the body and the camera view makes it seem to be close even though it is not, then why move it any closer? This also applies to sets. There is no need to build an entire house if all the action takes place in the living room. Consider painting backdrops rather than modeling every part of a scene.6. Use a minimum amount of keyframes. Too many keyframes can make the character appear to move in spastic motions. Sharp, cartoonlike movements are created with closely spaced keyframes. Floaty or soft, languid motions are the result of widely spaced keyframes. An animation will often be a mixture of both. Try to look for ways that will abbreviate the motions. You can retain the essential elements of an animation while reducing the amount of keyframes necessary to create a gesture.7.Anchor a part of the body. Unless your character is in the air, it should have some part of itself locked to the ground. This could be a foot, a hand, or both. Whichever portionis on the ground should be held in the same spot for a number of frames. This prevents unwanted sliding motions. When the model shifts its weight, the foot that touches down becomes locked in place. This is especially true with walking motions.There are a number of ways to lock parts of a model to the ground. One method is to use inverse kinematics. The goal object, which could be a null, automatically locks a foot or hand to the bottom surface. Another method is to manually keyframe the part that needs to be motionless in the same spot. The character or its limbs will have to be moved and rotated, so that foot or hand stays in the same place. If you are using forward kinematics, then this could mean keyframing practically every frame until it is time to unlock that foot or hand.8.A character should exhibit weight. One of the most challenging tasks in 3-D animation is to have a digital actor appear to have weight and mass. You can use several techniques to achieve this. Squash and stretch, or weight and recoil, one of the 12 principles of animation discussed in Chapter 12, is an excellent way to give your character weight.By adding a little bounce to your human, he or she will appear to respond to the force of gravity. For example, if your character jumps up and lands, lift the body up a little after it makes contact. For a heavy character, you can do this several times andhave it decrease over time. This will make it seem as if the force of the contact causes the body to vibrate a little.Secondary actions, another one of the 12 principles of animation discussed in Chapter 12, are an important way to show the effects of gravity and mass. Using the previous example of a jumping character, when he or she lands, the belly could bounce up and down, the arms could have some spring to them, the head could tilt forward, and so on.Moving or vibrating the object that comes in contact with the traveling entity is another method for showing the force of mass and gravity. A floor could vibrate or a chair that a person sits in respond to the weight by the seat going down and recovering back up a little. Sometimes an animator will shake the camera to indicate the effects of a force.It is important to take into consideration the size and weight of a character. Heavy objects such as an elephant will spend more time on the ground, while a light character like a rabbit will spend more time in the air. The hopping rabbit hardly shows the effects of gravity and mass.9. Take the time to act out the action. So often, it is too easy to just sit at the computer and try to solve all the problems of animating a human. Put some life into the performance by getting up and acting out the motions. This will make the character's actions more unique and also solve many timing and positioning problems. The best animators are also excellent actors. A mirror is an indispensable tool for the animator. Videotaping yourself can also be a great help.10. Decide whether to use IK, FK, or a blend of both. Forward kinematics and inverse kinematics have their advantages and disadvantages. FK allows full control over the motions of different body parts. A bone can be rotated and moved to the exact degree and location one desires. The disadvantage to using FK is that when your person has to interact within an environment, simple movements become difficult. Anchoring a foot to the ground so it does not move is challenging because whenever you move the body, the feet slide. A hand resting on a desk has the same problem.IK moves the skeleton with goal objects such as a null. Using IK, the task of anchoring feet and hands becomes very simple. The disadvantage to IK is that a great amount of control is packed together into the goal objects. Certain poses become very difficult to achieve.If the upper body does not require any interaction with its environment, then consider a blend of both IK and FK. IK can be set up for the lower half of the body to anchor the feet to the ground, while FK on the upper body allows greater freedom and precision of movements.Every situation involves a different approach. Use your judgment to decide which setup fits the animation most reliably.11. Add dialogue. It has been said that more than 90% of student animations that are submitted to companies lack dialogue. The few that incorporate speech in their animations make their work highly noticeable. If the animation and dialogue are well done, then those few have a greater advantage than their competition. Companies understand that it takes extra effort and skill tocreate animation with dialogue.When you plan your story, think about creating interaction between characters not only on a physical level but through dialogue as well. There are several techniques, discussed in this chapter, that can be used to make dialogue manageable.12. Use the graph editor to clean up your animations. The graph editor is a useful tool that all 3-D animators should become familiar with. It is basically a representation of all the objects, lights, and cameras in your scene. It keeps track of all their activities and properties.A good use of the graph editor is to clean up morph targets after animating facial expressions. If the default incoming curve in your graph editor is set to arcs rather than straight lines, you will most likely find that sometimes splines in the graph editor will curve below a value of zero. This can yield some unpredictable results. The facial morph targets begin to take on negative values that lead to undesirable facial expressions. Whenever you see a curve bend below a value of zero, select the first keyframe point to the right of the arc and set its curve to linear. A more detailed discussion of the graph editor will be found in a later part of this chapter.ANIMATING IN STAGESAll the various components that can be moved on a human model often become confusing if you try to change them at the same time. The performance quickly deteriorates into a mechanical routine if you try to alter all these parts at the same keyframes. Remember, you are trying to create human qualities, not robotic ones. Isolating areas to be moved means that you can look for the parts of the body that have motion over time and concentrate on just a few of those. For example, the first thing you can move is the body and legs. When you are done moving them around over the entire timeline, then try rotating the spine. You might do this by moving individual spine bones or using an inverse kinematics chain. Now that you have the body moving around and bending, concentrate on the arms. If you are not using an IK chain to move the arms, hands, and fingers, then rotate the bones for the upper and lower arm. Do not forget the wrist. Finger movements can be animated as one of the last parts. Facial expressions can also be animated last.Example movies showing the same character animated in stages can be viewed on the CD-ROM as CD11-1 AnimationStagesMovies. Some sample images from the animations can also be seen in Figure 11-1. The first movie shows movement only in the body and legs. During the second stage, the spine and head were animated. The third time, the arms were moved. Finally, in the fourth and final stage, facial expressions and finger movements were added.Animating in successive passes should simplify the process. Some final stages would be used to clean up or edit the animation.Sometimes the animation switches from one part of the body leading to another. For example, somewhere during the middle of an animation the upper body begins to lead the lower one. In a case like this, you would then switch from animating the lower body first to moving the upper part before the lower one.The order in which one animates can be a matter of personal choice. Some people may prefer to do facial animation first or perhaps they like to move the arms before anything else. Following is a summary of how someone might animate a human.1. First pass: Move the body and legs.2. Second pass: Move or rotate the spinal bones, neck, and head.3. Third pass: Move or rotate the arms and hands.4. Fourth pass: Animate the fingers.5. Fifth pass: Animate the eyes blinking.6. Sixth pass: Animate eye movements.7. Seventh pass: Animate the mouth, eyebrows, nose, jaw, and cheeks (you can break these up into separate passes).Most movement starts at the hips. Athletes often begin with a windup action in the pelvic area that works its way outward to the extreme parts of the body. This whiplike activity can even be observed in just about any mundane act. It is interesting to note that people who study martial arts learn that most of their power comes from the lower torso. Students are often too lazy to make finger movements a part of their animation. There are several methods that can make the process less time consuming.One way is to create morph targets of the finger positions and then use shape shifting to move the various digits. Each finger is positioned in an open and fistlike closed posture. For example, the sections of the index finger are closed, while the others are left in an open, relaxed position for one morph target. The next morph target would have only the ring finger closed while keeping the others open. During the animation, sliders are then used to open and close the fingers and/or thumbs.Another method to create finger movements is to animate them in both closed and open positions and then save the motion files for each digit. Anytime you animate the same character, you can load the motions into your new scene file. It then becomes a simple process of selecting either the closed or the open position for each finger and thumb and keyframing them wherever you desire.DIALOGUEKnowing how to make your humans talk is a crucial part of character animation. Once you add dialogue, you should notice a livelier performance and a greater personality in your character. At first, dialogue may seem too great a challenge to attempt. Actually, if you follow some simple rules, you will find that adding speech to your animations is not as daunting a task as one would think. The following suggestions should help.DIALOGUE ESSENTIALS1. Look in the mirror. Before animating, use a mirror or a reflective surface such as that on a CD to follow lip movements and facial expressions.2. The eyes, mouth, and brows change the most. The parts of the face that contain the greatest amount of muscle groups are the eyes, brows, and mouth. Therefore, these are the areas that change the most when creating expressions.3. The head constantly moves during dialogue. Animate random head movements, no matter how small, during the entire animation. Involuntary motions of the head make a point without having to state it outright. For example, nodding and shaking the head communicate, respectively, positive and negative responses. Leaning the head forward can show anger, while a downward movement communicates sadness. Move the head to accentuate and emphasize certain statements. Listen to the words that are stressed and add extra head movements to them.4. Communicate emotions. There are six recognizable universal emotions: sadness, anger, joy, fear, disgust, and surprise. Other, more ambiguous states are pain, sleepiness, passion, physical exertion, shyness, embarrassment, worry, disdain, sternness, skepticism, laughter, yelling, vanity, impatience, and awe.5. Use phonemes and visemes. Phonemes are the individual sounds we hear in speech. Rather than trying to spell out a word, recreate the word as a phoneme. For example, the word computer is phonetically spelled "cumpewtrr." Visemes are the mouth shapes and tongue positions employed during speech. It helps tremendously to draw a chart that recreates speech as phonemes combined with mouth shapes (visemes) above or below a timeline with the frames marked and the sound and volume indicated.6. Never animate behind the dialogue. It is better to make the mouth shapes one or two frames before the dialogue.7. Don't overstate. Realistic facial movements are fairly limited. The mouth does not open that much when talking.8. Blinking is always a part of facial animation. It occurs about every two seconds. Different emotional states affect the rate of blinking. Nervousness increases the rate of blinking, while anger decreases it.9. Move the eyes. To make the character appear to be alive, be sure to add eye motions. About 80% of the time is spent watching the eyes and mouth, while about 20% is focused on the hands and body.10. Breathing should be a part of facial animation. Opening the mouth and moving the head back slightly will show an intake of air, while flaring the nostrils and having the head nod forward a little can show exhalation. Breathing movements should be very subtle and hardly noticeable...外文资料翻译—译文部分人体动画基础(引自 Peter Ratner.3D Human Modeling andAnimation[M].America:Wiley,2003:243~249)如果你读到了这部分，说明你很可能已构建好了人物角色，为它创建了纹理，建立起了人体骨骼，为面部表情制作了morph修改器并在模型周围安排好了灯光。

三维建模数字化设计英语In the realm of modern design, 3D modeling has revolutionized the way we conceptualize and create. It allows designers to visualize their ideas in a tangible form,bringing innovation to life with digital precision.The process of 3D modeling starts with a concept, whichis then translated into a digital blueprint. This blueprintis the foundation upon which the model is built, layer by layer, in a virtual space.As the model takes shape, each detail is carefullycrafted to ensure accuracy and functionality. The digitaltools at our disposal offer unparalleled control over the design, enabling us to make adjustments with ease.The versatility of 3D modeling extends beyond the design phase. It is instrumental in the prototyping process,allowing for the creation of physical models that can betested and refined before production.Moreover, 3D modeling has a significant impact on the manufacturing industry. It streamlines the production process, reducing costs and time, while ensuring the highest qualityof the final product.In the field of education, 3D modeling is an invaluable tool for teaching complex concepts. It provides students witha hands-on approach to learning, enhancing their understanding and creativity.Lastly, the integration of 3D modeling in various industries, from architecture to entertainment, showcases its potential to shape the future of design and innovation. It is a testament to the power of technology in transforming the way we create and interact with the world around us.。

Available online at vailable online at Procedia Engineering Procedia Engineering 00 (2011) 000–000 /locate/procedia The Twelfth East Asia-Pacific Conference on Structural Engineering and ConstructionApplication of 3D Bridge Information Modeling to Designand Construction of BridgesCS Shim 1a , NR Yun 2, HH Song 31Department of Civil and Env. Engineering, Chung-Ang University (csshim@cau.ac.kr)2 Department of Civil and Env. Engineering, Chung-Ang University (nuri58@)3 Department of Civil and Env. Engineering, Chung-Ang University (glay-hyune@) AbstractBuilding information modeling (BIM) is a new technology in bridge construction industry. 3D models can provide perfect numerical expression of drawings from design results. 3D information models for bridge structures improve design quality in terms of accurate drawings, constructability and collaboration. However, there are lots of obstacles to apply these techniques to actual bridge projects. In this paper, extensible information schema for bridges is proposed to enable interoperability between different design and construction processes. From the planning stage of a bridge construction project to the construction stage, the proposed bridge information models were applied to enhance current practices. Digital mock-up, parametric modeling, 4D and 5D simulation were conducted. From several applications for four years, a design guideline of 3D information models was suggested. It is essential to change current processes for the effective use of BIM techniques in bridge construction industry.© 2011 Published by Elsevier Ltd.KEYWORDS: building information modeling; 3D model; bridge structure; interoperability; information schema.1.INTRODUCTIONFragmented information transfer during the bridge lifecycle causes additional cost and time for locating and validating information. Object-based 3D models with metadata can be a shared information model for the effective collaborative design, construction and maintenance. Well-organized data architecture for the infrastructures is essential for the effective cooperation between engineers.aCorresponding author: Email: csshim@cau.ac.kr a Presenter: Email: csshim@cau.ac.kr1877–7058 © 2011 Published by Elsevier Ltd.doi:10.1016/j.proeng.2011.07.010Procedia Engineering 14 (2011) 95–9996 C.S. Shim et al. / Procedia Engineering 14 (2011) 95–992Author name / Procedia Engineering 00 (2011) 000–000A construction project life-cycle management system was proposed for the enhancement of productivityin construction industry. Architectures of geometry and information for several bridge types were built and utilized for collaborative works. Each information layer includes necessary metadata for the data sharing and knowledge accumulation during construction project processes. This information has its own data architecture which is derived from similar concept of product breakdown structure (PBS) and work breakdown structure (WBS). The integrated information model realized a virtual construction system for bridges and dramatically increased the productivity of the whole management process. Prototypes for the bridge information model were suggested and pilot tests were conducted to evaluate their effectiveness and to derive the guidelines for the future 3D models. The applications were mainly for international bridge construction projects and for domestic bridges. Because of obstacles in practices, 3D models were utilized for specific processes in the project. Evaluated effects of the applications were summarized and a guideline of 3D model based design was proposed.2. 3D BRIDGE INFORMATION MODELFor the effective collaboration of bridge construction projects, it is essential to define architectures of the information models and information delivery manuals. WBS and OBS (organization breakdown structure) need to be connected to PBS in the construction project lifecycle management (CPLM) system.Each participant has predefined tasks and outcomes from the tasks to share essential information.2.1. Architecture of 3D Bridge Information ModelThe architecture of the geometry and the information for bridges was built as shown in Figure 1.Geometry models are connected to the information database by defining the code numbers which are defined before modeling. Well organized libraries for 3D information models can be used. The design information layer has metadata on requirements, design codes, geometry, construction data and so on.The construction layer has data on drawings, real data for material and products, schedules and so on. The maintenance layer for the operation has the final geometry, material data, products and their suppliers and inspection/repair history. The integrated information model can realize virtual construction system for bridges and dramatically increase the productivity of the whole management process (Shim et al. 2008, 2009).Neutral file format XML schemaFigure 1: Architecture of 3D Bridge Information Model.C.S. Shim et al. / Procedia Engineering 14 (2011) 95–9997 Author name / Procedia Engineering 00 (2011) 000–000 32.2. Delivery and Share of Information ModelsInteroperability is the crucial for the sharing and delivery of the information. Until now, the 3D CAD engines or solutions are not enough for the effective use of the system. Technical advancement is needed to accommodate the requirements from all the participants of a construction projects. Before any international or national standard of the information delivery manual (IDM), an information delivery system for a specific bridge construction project was constructed as shown in Figure 2.For the sharing of the 3D information models in the different solutions, a neutral file format is needed and information database in the format of neutral file such as XML is also an essential part. By using these predefined formats, each task for the engineering process can be successfully executed for engineering applications. Information DeliveryManual Engineering ApplicationsPlanning Design Construction Maintenance Removal CPLM System PBS WBS Schedule cost GeometryNeutral filesData Mgmt.System Work Process(Task)Organization Breakdown StructureFigure 2: Information Delivery System.3. APPLICATIONS AND 3D DESIGN GUIDELINEBuilding information modeling (BIM) is a new technology in civil engineering industry. In order to reduce initial cost to adopt BIM for bridge construction, several pilot applications were conducted in Korea. From these applications and investigating the current technologies in ICT, a 3D design guideline for civil engineering industry was developed.3.1. Applications to BridgesIntegrated design and construction of bridge structures can be accomplished by several principles such as parametric modeling, layered model architecture, interoperable schema for information. As shown in Figure 3, each component of a bridge is modeled with basic parameters and connected with other components by layered architecture of geometry models (Lee et al. 2010). Many engineers can cooperate in the design of a bridge and share the essential information.98 C.S. Shim et al. / Procedia Engineering 14 (2011) 95–994Author name / Procedia Engineering 00 (2011) 000–000Concrete ReinforcementT endonStrutFigure 3: Layered concrete box girder bridge model.A well-organized bridge information model can dramatically enhance the design revision process andcommunication with workers on the construction site. Currently, main applications of BIM technologies are digital mock-up (DMU), shop drawings, local analysis, estimation, 4D simulation, and 5D simulation.As shown in Figure 4, important bridge construction projects adopted BIM technologies mainly in the beginning stage of construction. By building 3D models for a bridge, engineers can check constructability by DMU and produce accurate shop drawings. In Korea, remarkable number of cable supported bridges used 3D models (Kim et al. 2009).Even though the client does not require 3D models for the design, general contractors found the effectiveness of BIM technologies to reduce construction cost and risk. 4D simulations with detailed activities in 3D models enhanced engineer’s knowledge of a bridge and resulted in effective usage of resources for the construction. Some contractors have started innovation of their processes by adopting BIM technologies.Figure 4: Typical applications of bridges.3.2. 3D Design GuidelineThere are many BIM guidelines for building structures but those guidelines are not sufficient for civil infrastructures. 3D information models have much dependency on a CAD engine. From the pilot applications, a 3D design guideline of civil infrastructures was proposed. Main contents of the guideline are as follows;C.S. Shim et al. / Procedia Engineering 14 (2011) 95–9999Author name / Procedia Engineering 00 (2011) 000–000 5 Part I: General principles (classification, 3D object model, information, process, management and security, collaboration)Part II: Interoperability for design solutions (design solution, 2D drawings)Part III: Interoperability for analysis (3D finite element model, 1D and 2D finite element model)Part IV: Interoperability for estimation (classification, WBS, CBS, estimation)Part V: Interoperability for virtual reality (active simulation, 4D, 5D)Part VI: Interoperability and information systemIn this guideline, significant suggestions to overcome obstacles to adopt BIM technologies in civil engineering industry are derived. Related unreasonable systems for designers and contractors are listedand improved systems are proposed and several pilot applications are also summarized.4. CONCLUSIONSEven though ICT can provide innovative way of engineering, the most important contents are engineer’s knowledge and previous project experience. BIM technologies support engineers to improve productivityand to reduce risk. Collaboration is an essential part of the innovation and requires process innovation.In this paper, extensible information schema for bridges is proposed to enable interoperability between different design and construction processes. From the planning stage of a bridge construction project tothe construction stage, the proposed bridge information models were applied to enhance current practices.Digital mock-up, parametric modeling, 4D and 5D simulation were conducted. From several applications,a design guideline of 3D information models was suggested.5. ACKNOWLEDGMENTSThis research was supported by the Virtual Construction Research Center sponsored by the Ministry of Land, Transport and Maritime Affairs of Korea. This support is gratefully acknowledged.REFERENCES[1] Kim YH, Kim SH, Shim CS (2009). Construction management using integrated 3D information model technology.International Conference on Computational Design in Engineering (CODE2009), Seoul, pp. 29-32.[2] Lee KM, Lee YB, Shim CS, Park KL (2010). Bridge information models for construction of a concrete box-girder bridge.Structure and Infrastructure Engineering, First published on: 27 April 2010 (iFirst).[3] Shim CS, Lee KM, Son WS, Moon JW (2008). Collaborative Design of High-speed Railway Lines using 3D informationmodels. Proc. of IABSE Conference on Information and Communication Technology for Bridges, Buildings andConstruction Practice, C33.[4] Shim CS, Lee KM, Kim DW, Lee YB, Park KL (2009). Integrated construction project planning using 3D informationmodels, ICCEM & ICCPM, Jeju, S18-2.。