地理信息系统教程课后参考答案

地理信息系统原理课后作业答案本页仅作为文档封面，使用时可以删除This document is for reference only-rar21year.March地理信息系统原理课后作业答案第1章绪论1 什么叫信息、数据它们有何区别信息有何特点答：信息是客观事物的存在及演变情况的反映。

对于计算机而言，数据是指输入到计算机并能为计算机进行处理的一切现象（数字、文字、符号、声音、图像等），在计算机环境中数据是描述实体或对象的唯一工具。

数据是用以载荷信息的物理符号，没有任何实际意义，只是一种数学符号的集合，只有在其上加上某种特定的含义，它才代表某一实体或现象，这时数据才变成信息。

信息的特点：①客观性②适用性③传输性④共享性。

2 什么叫空间数据、地图？举例说明空间数据有哪几种类型。

答：空间数据是以点、线、面等方式采用编码技术对空间物体进行特征描述及在物体间建立相互联系的数据集。

地图是表达客观事物的地理分布及其相互联系的空间模型，是反映地理实体的图形，是对地理实体简化和再现。

空间数据主要有点、线、面三种类型。

例如，地图上的点可以是矿点、采样点、高程点、地物点和城镇等；线可以是地质界线、铁路、公路、河流等；面可以是土壤类型、水体、岩石类型等。

3 什么叫地理信息、地学信息、信息系统、地理信息系统它们之间有何区别答：地理信息是表征地理系统诸要素的数量、质量、分布特征、相互联系和变化规律的数字、文字、图像和图形等的总称。

地学信息所表示的信息范围更广，它不仅来自地表，还包括地下、大气层，甚至宇宙空间。

凡是与人类居住的地球有关的信息都是地学信息。

能对数据和信息进行采集、存贮、加工和再现，并能回答用户一系列问题的系统称为信息系统。

地理信息系统（GIS）是在计算机软硬件支持下，以采集、存贮、管理、检索、分析和描述空间物体的定位分布及与之相关的属性数据，并回答用户问题等为主要任务的计算机系统。

区别：地理信息属于空间信息，其位置的识别是与数据联系在一起的，这是地理信息区别于其它类型信息的最显著的标志。

第一章绪论1.什么是数据和信息？它们有何联系和区别？定义：数据是指某一目标定性、定量描述的原始资料，包括数字、文字、符号、图形、图像以及它们能够转换成的数据等形式。

信息是向人们或机器提供关于现实世界新的事实的知识，是数据、消息中所包含的意义。

联系和区别：信息与数据是不可分离的。

信息由与物理介质有关的数据表达，数据中所包含的意义就是信息。

信息是对数据解释、运用与解算，数据即使是经过处理以后的数据，只有经过解释才有意义，才成为信息；就本质而言，数据是客观对象的表示，而信息则是数据内涵的意义，只有数据对实体行为产生影响时才成为信息。

数据是记录下来的某种可以识别的符号，具有多种多样的形式，也可以加以转换，但其中包含的信息内容不会改变。

即不随载体的物理设备形式的改变而改变。

信息可以离开信息系统而独立存在，也可以离开信息系统的各个组成和阶段而独立存在；而数据的格式往往与计算机系统有关，并随载荷它的物理设备的形式而改变。

数据是原始事实，而信息是数据处理的结果。

不同知识、经验的人，对于同一数据的理解，可得到不同信息。

2.什么是地理信息系统（GIS）?与地图数据库有什么异同?与地理信息的关系是什么?GIS定义：GIS是一个发展的概念。

不同领域、不同专业对GIS的理解不同，目前没有完全统一的被普遍接受的定义。

定义①：是对地理环境有关问题进行分析和研究的一门学科，它将地理环境的各种要素，包括它们的空间位置形状及分布特征和与之有关的社会、经济等专题信息以及这些信息之间的联系等进行获取、组织、存储、检索、分析，并在管理、规划与决策中应用。

定义②：是在计算机软硬件支持下，以采集、存储、管理、检索、分析和描述空间物体的定位分布及与之相关的属性数据，并回答用户问题为主要任务的计算机系统。

定义③：是为了获取、存储、检索、分析和显示空间定位数据而建立的计算机化的数据库管理系统。

定义④：地理信息系统是一种决策支持系统。

它的定义由两方面组成，一方面，地理信息系统是一门学科，是描述、存储、分析和输出空间信息的理论和方法的一门新兴交叉学科；另一方面，地理信息系统是一个技术系统，是以空间数据库为基础，采用地理模型分析方法，适时提供多种空间和动态的地理信息，为地理研究和地理决策服务的计算机技术系统。

第一章绪论1.什么是数据和信息？它们有何联系和区别？定义：数据是指某一目标定性、定量描述的原始资料，包括数字、文字、符号、图形、图像以及它们能够转换成的数据等形式。

信息是向人们或机器提供关于现实世界新的事实的知识，是数据、消息中所包含的意义。

联系和区别：信息与数据是不可分离的。

信息由与物理介质有关的数据表达，数据中所包含的意义就是信息。

信息是对数据解释、运用与解算，数据即使是经过处理以后的数据，只有经过解释才有意义，才成为信息；就本质而言，数据是客观对象的表示，而信息则是数据内涵的意义，只有数据对实体行为产生影响时才成为信息。

数据是记录下来的某种可以识别的符号，具有多种多样的形式，也可以加以转换，但其中包含的信息内容不会改变。

即不随载体的物理设备形式的改变而改变。

信息可以离开信息系统而独立存在，也可以离开信息系统的各个组成和阶段而独立存在；而数据的格式往往与计算机系统有关，并随载荷它的物理设备的形式而改变。

数据是原始事实，而信息是数据处理的结果。

不同知识、经验的人，对于同一数据的理解，可得到不同信息。

2.什么是地理信息系统（GIS）?与地图数据库有什么异同?与地理信息的关系是什么?GIS定义：GIS是一个发展的概念。

不同领域、不同专业对GIS的理解不同，目前没有完全统一的被普遍接受的定义。

定义①：是对地理环境有关问题进行分析和研究的一门学科，它将地理环境的各种要素，包括它们的空间位置形状及分布特征和与之有关的社会、经济等专题信息以及这些信息之间的联系等进行获取、组织、存储、检索、分析，并在管理、规划与决策中应用。

定义②：是在计算机软硬件支持下，以采集、存储、管理、检索、分析和描述空间物体的定位分布及与之相关的属性数据，并回答用户问题为主要任务的计算机系统。

定义③：是为了获取、存储、检索、分析和显示空间定位数据而建立的计算机化的数据库管理系统。

定义④：地理信息系统是一种决策支持系统。

它的定义由两方面组成，一方面，地理信息系统是一门学科，是描述、存储、分析和输出空间信息的理论和方法的一门新兴交叉学科；另一方面，地理信息系统是一个技术系统，是以空间数据库为基础，采用地理模型分析方法，适时提供多种空间和动态的地理信息，为地理研究和地理决策服务的计算机技术系统。

1. 地理信息系统的定义是由两个部分组成的。

一方面，地理信息系统是一门学科，是描述、存储、分析和输出空间信息的理论和方法的一门新兴的交叉学科；另一方面，地理信息系统是一个技术系统，是以地理空间数据库为基础，采用地理模型分析方法，适时提供多种空间的和动态的地理信息，为地理研究和地理决策服务的计算机技术系统。

2. TIN即不规则三角网（Triangulated Irregular Network），是一种表示数字高程模型的方法。

TIN模型根据区域有限个点集将区域划分为相连的三角面网络，区域中任意点落在三角面的顶点、边上或三角形内。

如果点不在顶点上，该点的高程值通常通过线性插值的方法得到。

3. 元数据是关于数据的描述性数据信息，它应尽可能多地反映数据集自身的特征规律，以便于用户对数据集的准确、高效与充分的开发与利用。

元数据的内容包括对数据集的描述、）对数据质量的描述、对数据处理信息的说明、对数据转换方法的描述、对数据库的更新、集成等的说明。

4. 信息是向人们或机器提供关于现实世界新的事实的知识，是数据、消息中所包含的意义，它不随载体的物理设备形式的“地理信息系统教程”习题及参考答案第一章绪论1.什么是数据和信息？它们有何联系和区别？定义：数据是指某一目标定性、定量描述的原始资料，包括数字、文字、符号、图形、图像以及它们能够转换成的数据等形式。

信息是向人们或机器提供关于现实世界新的事实的知识，是数据、消息中所包含的意义。

联系和区别：信息与数据是不可分离的。

信息由与物理介质有关的数据表达，数据中所包含的意义就是信息。

信息是对数据解释、运用与解算，数据即使是经过处理以后的数据，只有经过解释才有意义，才成为信息；就本质而言，数据是客观对象的表示，而信息则是数据内涵的意义，只有数据对实体行为产生影响时才成为信息。

数据是记录下来的某种可以识别的符号，具有多种多样的形式，也可以加以转换，但其中包含的信息内容不会改变。

第一章绪论1.什么是数据和信息它们有何联系和区别定义：数据是指某一目标定性、定量描述的原始资料，包括数字、文字、符号、图形、图像以及它们能够转换成的数据等形式。

信息是向人们或机器提供关于现实世界新的事实的知识，是数据、消息中所包含的意义。

联系和区别：信息与数据是不可分离的。

信息由与物理介质有关的数据表达，数据中所包含的意义就是信息。

信息是对数据解释、运用与解算，数据即使是经过处理以后的数据，只有经过解释才有意义，才成为信息；就本质而言，数据是客观对象的表示，而信息则是数据内涵的意义，只有数据对实体行为产生影响时才成为信息。

数据是记录下来的某种可以识别的符号，具有多种多样的形式，也可以加以转换，但其中包含的信息内容不会改变。

即不随载体的物理设备形式的改变而改变。

信息可以离开信息系统而独立存在，也可以离开信息系统的各个组成和阶段而独立存在；而数据的格式往往与计算机系统有关，并随载荷它的物理设备的形式而改变。

数据是原始事实，而信息是数据处理的结果。

不同知识、经验的人，对于同一数据的理解，可得到不同信息。

2.什么是地理信息系统（GIS）与地图数据库有什么异同与地理信息的关系是什么GIS定义：GIS是一个发展的概念。

不同领域、不同专业对GIS的理解不同，目前没有完全统一的被普遍接受的定义。

定义①：是对地理环境有关问题进行分析和研究的一门学科，它将地理环境的各种要素，包括它们的空间位置形状及分布特征和与之有关的社会、经济等专题信息以及这些信息之间的联系等进行获取、组织、存储、检索、分析，并在管理、规划与决策中应用。

定义②：是在计算机软硬件支持下，以采集、存储、管理、检索、分析和描述空间物体的定位分布及与之相关的属性数据，并回答用户问题为主要任务的计算机系统。

定义③：是为了获取、存储、检索、分析和显示空间定位数据而建立的计算机化的数据库管理系统。

定义④：地理信息系统是一种决策支持系统。

它的定义由两方面组成，一方面，地理信息系统是一门学科，是描述、存储、分析和输出空间信息的理论和方法的一门新兴交叉学科；另一方面，地理信息系统是一个技术系统，是以空间数据库为基础，采用地理模型分析方法，适时提供多种空间和动态的地理信息，为地理研究和地理决策服务的计算机技术系统。

地理信息系统概论课后习题部分答案【可编辑】第一章1、什么是地理信息系统(GIS),它与一般计算机应用系统有哪些异同点,答:地理信息系统:是由计算机硬件、软件和不同的方法组成的系统，该系统设计支持空间数据的采集、管理、处理、分析、建模和显示，以便解决复杂的规划和管理问题。

GIS脱胎于地图学，是计算机科学、地理学、测绘遥感学、环境科学、城市科学、空间科学、信息科学和管理科学等众多学科交叉融合而成的新兴学科。

但是，地理信息系统与这学科和系统之间既有联系又有区别:(1)GIS与机助制图系统机助制图是地理信息系统得主要技术基础，它涉及GIS中的空间数据采集、表示、处理、可视化甚至空间数据的管理。

地理信息系统和数字制图系统的主要区别在于空间分析方面。

一个功能完善的地理信息系统可以包含数字制图系统的所有功能，此外它还应具有丰富的空间分析功能。

(2)GIS与DBMS(数据库管理系统)GIS除需要功能强大的空间数据的管理功能之外，还需要具有图形数据的采集、空间数据的可视化和空间分析等功能。

因此，GIS在硬件和软件方面均比一般事务数据库更加复杂，在功能上也比后者要多地多。

(3)GIS与CAD系统二者虽然都有参考系统，都能描述图形，但CAD系统只处理规则的几何图形、属性库功能弱，更缺乏分析和判断能力。

(4)GIS与遥感图像处理的系统遥感图像处理的系统是专门用于对遥感图像数据处理进行分析处理的软件。

它主要强调对遥感栅格数据的几何处理、灰度处理和专题信息提取。

这种系统一般缺少实体的空间关系描述，难以进行某一实体的属性查询和空间关系查询以及网络分析等功能。

2、地理信息系统有哪几个主要部分组成,它的基本功能有哪些,试举目前广泛应用的两个基础地理信息系统软件为例，列出它们的功能分类表，并比较异同点,(1)系统硬件:包括各种硬件设备，是系统功能实现的物质基础;(2)系统软件:支持数据采集、存储、加工、回答用户问题的计算机程序系统;(3)空间数据:系统分析与处理的对象，构成系统的应用基础;(4)应用人员:GIS服务的对象，分为一般用户和从事建立、维护、管理和更新的高级用户;(5)应用模型:解决某一专门应用的应用模型，是GIS技术产生社会经济效益的关键所在。

第一章1、什么是GIS？它具有什么特点？答：地理信息系统（GIS , Geographic Information System）是在计算机硬、软件系统支持下，对现实世界（资源与环境）的研究和变迁的各类空间数据及描述这些空间数据特性的属性进行采集、储存、管理、运算、分析、显示和描述的技术系统特点有：○1具有采集、管理、分析和输出多种地理空间信息的能力；○2以地理研究和地理决策为目的，以地理模型方法为手段，具有空间分析、多要素综合分析和动态预测的能力；并能产生高层次的地理信息。

○3具有公共的地理定位基础，所有的地理要素，要按经纬度或者特有的坐标系统进行严格的空间定位。

○4由计算机系统支持进行空间地理数据管理，并由计算机程序模拟常规的或专门的地理分析方法，作用于空间数据，产生有用信息，完成人类难以完成的任务。

○5地理信息系统从外部来看，它表现为计算机软硬件系统；而其内涵确是由计算机程序和地理数据组织而成的地理空间信息模型，是一个逻辑缩小的、高度信息化的地理系统。

信息的流动及信息流动的结果，完全由计算机程序的运行和数据的交换来仿真2、GIS与其它信息系统有什么区别答：第一，GIS有别于DBMS（数据库管理系统），GIS具有以某种选定的方式对空间数据进行解释和判断的能力，而不是简单的数据管理，这种能力使用户能得到关于数据的知识，因此，GIS是能对空间数据进行分析的DBMS，GIS必须包含DBMS。

第二，GIS有别于MIS（管理信息系统），GIS要对图形数据和属性数据库共同管理、分析和应用，GIS的软硬件设备要复杂、系统功能要强；MIS则只有属性数据库的管理，即使存贮了图形，也是以文件形式管理，图形要素不能分解、查询、没有拓扑关系。

管理地图和地理信息的MIS不一定就是GIS，MIS在概念上更接近DBMS。

第三，GIS有别于地图数据库，地图数据库仅仅是将数字地图有组织地存放起来，不注重分析和查询，不可能去综合图形数据和属性数据进行深层次的空间分析，提供辅助决策的信息，它只是GIS的一个数据源。

Chapter 1 Review Questions1. Define geospatial data.Geospatial data are data that describe both the locations and characteristics of spatial features such as roads, land parcels, and vegetation stands on the Earth’s surface.2. Describe an example of GIS application from your discipline.[Refer to Section 1.2 and describe an example of GIS application from geography, forestry, geology, environmental studies, business, public health, etc.]3. Go to the USGS National Map website (/viewer.html) and see what kinds of geospatial data are available for download.[Go to the above website, follow the instructions at the website, and check for geospatial data available for download.]4. Go to the National Institute of Justice website(/nij/maps/) and read how GIS is used for crime analysis.[Go to the above website. “Learn about Crime Mapping” is included in the lower right corner. It lists three topics: What is GIS; Mapping Crime: Principle and Practice; and Understanding Hot Spots.]5. Location-based services are probably the most commercialized GIS-related field. Search for “location-based service” in Wikipedia(/) and read what has been posted on the topic. Accessed on August 9, 2010, Wikipedia defines a location-based service as “an information and entertainment service, accessible with mobile devices through the mobile network and utilizing the ability to make use of the geographical position of the mobile device.”6. What types of software and hardware are you currently using for GIS classes and projects?[Name the software package (e.g., ArcGIS 10.2) and the hardware (e.g., PC Windows 7) for the GIS class.]7. Try the map locators offered by Microsoft Virtual Earth, Yahoo Maps, and Google Maps, respectively. State the major differences among these three systems.[Go to each website, try the map locator, and summarize, in your opinion, the major differences between the map locators.]8. Define geometries and attributes as the two components of GIS data. Geometries describe the locations of spatial features, which may be discrete or continuous. Attributes describe the characteristics of spatial features.9. Explain the difference between vector data and raster data.Vector data use points and their x-, y-coordinates to represent spatial features of points, lines, and areas. Raster data use a grid and grid cells to represent the spatial variation of a feature.10. Explain the difference between the georelational data model and theobject-based data model.The georelational data model uses a split system to store geometries and attributes. The object-based data model stores geometries and attributes in a single system.11. What does it mean by "volunteered geographic information"? Volunteered geographic information is geographic information generated by the public using web applications and services.12. Suppose you are required to do a GIS project for a class. What kinds of activities or operations do you have to perform to complete the project?[The project will most likely involve data input, data management, data display, data exploration, data analysis, and, in some cases, GIS models and modeling.]13. Name two examples for vector data analysis.Examples for vector data analysis include buffering, overlay, distance measurement, spatial statistics, and map manipulation.14. Name two examples of raster data analysis.Examples of raster data analysis includes local, neighborhood, zonal, and global operations.15. Describe an example from your discipline, in which a GIS can provide useful tools for building a model.[A GIS can be used for building simple models. For more complex models such as environmental models, a GIS is typically used for data visualization, database management, and data exploration.]Chapter 2 Review Questions1. Describe the three levels of approximation of the shape and size of the Earth for GIS applications.The simplest model for approximating the Earth is a sphere, which is typically used in discussing map projections. But the Earth is wider along the equator than between the poles. Therefore a better approximation to the shape of the Earth is a spheroid, also called ellipsoid, an ellipse rotated about its minor axis. The geoid is an even closer approximation of the Earth than a spheroid. The geoid has an irregular surface, which is affected by irregularities in the density of the Earth’s crust and mantle.2. Why is the datum important in GIS?A datum is important in GIS because it serves as the reference or base for calculating the geographic coordinates of a location.3. Describe two common datums used in the United States.The first common datum used in the United States is NAD27(North American Datum of 1927), which is a local datum based on the Clarke 1866 ellipsoid, aground-measured spheroid. The second common datum is NAD83(North American Datum of 1983), an Earth-centered or geocentered datum, based on the GRS80 (Geodetic Reference System 1980) ellipsoid.4. Pick up a USGS quadrangle map of your area. Examine the information on the map margin. If the datum is changed from NAD27 to NAD83, what is the expected horizontal shift?[The expected horizontal shift is listed on the lower margin of a USGS quadrangle map.]5. Go to the NGS-CORS website (/CORS/). How many continuously operating reference stations do you have in your state? Use the links at the website to learn more about CORS.[Go to the above website, click a state on the map, and see how many continuously operating reference stations are within the state.] Surveyors, GIS professionals, engineers, scientists, and others can apply CORS data to position points at which GPS data have been collected. The CORS system enables positioning accuracies that approach a few centimeters relative to the National Spatial Reference System, both horizontally and vertically.6. Explain the importance of map projection.A map projection offers a couple of advantages. First, a map projection allows us to use two-dimensional maps, either paper or digital, instead of a globe. Second, a map projection allows us to work with plane or projected coordinates rather than longitude and latitude values. Computations with geographic coordinates are more complex.7. Describe the four types of map projections by the preserved property.A conformal projection preserves local angles and shapes. An equivalent projection represents areas in correct relative size. An equidistant projection maintains consistency of scale along certain lines. And an azimuthal projection retains certain accurate directions.8. Describe the three types of map projections by the projection or developable surface.A cylindrical projection uses a cylinder as the projection or developable surface, a conic projection uses a cone, and an azimuthal projection uses a plane.9. Explain the difference between the standard line and the central line.A standard line refers to the line of tangency between the projection surface and the reference globe. In other words, there is no projection distortion along a standard line. The central lines (i.e., the central parallel and meridian) define the center of a map projection.10. How is the scale factor related to the principal scale?The scale factor is defined as the ratio of the local scale to the principal scale. In other words, the scale factor is the normalized local scale.11. Name two commonly used projected coordinate systems that are based on the transverse Mercator projection.They are the Universal Transverse Mercator (UTM) grid system and the State Plane Coordinate (SPC) system.12. Google the GIS data clearinghouse for your state. Go to the clearinghouse website. Does the website use a common coordinate system for the statewide data sets? If so, what is the coordinate system? What are the parameters values for the coordinate system? And, is the coordinate system based on NAD27 orNAD83?[The coordinate system information is typically included on the clearinghouse page for data download.]13. Explain how a UTM zone is defined in terms of its central meridian, standard meridian, and scale factor.A UTM zone is mapped onto a secant case transverse Mercator projection, with a scale factor of 0.9996 at the central meridian. The standard meridians are 180 kilometers to the east and west of the central meridian.14. Which UTM zone are you in? Where is the central meridian of the UTM zone?[The answer can be found on the margin of a 1:24,000-scale USGS topographic map. It may also be available in the download information of the clearinghouse for your area. Figure 2.12 in the text can also provide the answer, but it is not as clear as on a USGS topographic map.]15. How many SPC zones does your state have? What map projections are the SPC zones based on?[Information on the SPC zones is available on the USGS topographic maps. It may also be available in the download information of the clearinghouse for your area.]16. Describe how on-the-fly projection works.A GIS package, if it offers on-the-fly projection, can use the projection files available with the data sets and automatically convert the data sets to a common coordinate system. This common coordinate system is by default the coordinate system of the first data set in display.Chapter 3 Review Questions1. Google the GIS data clearinghouse for your state. Go to the clearinghouse website. What data format(s) does the website use for delivering vector data? [The data formats may include the shapefile and the geodatabase from Esri.]2. Name the three types of simple features used in GIS and their geometric properties.A point has 0 dimension and has only the property of location. A line isone-dimensional and has the property of length. And a polygon is two-dimensional and has the properties of area (size) and perimeter.3. Draw a stream network, and show how the topological relationships of connectivity and contiguity can be applied to the coverage.[Draw a simple stream network, insert a node at each stream junction for connectivity, and mark the flow direction of each stream segment for contiguity.]4. How many arcs connect at node 12 in Figure 3.8?Three arcs (1, 2, and 3) connect at node 12.5. Suppose an arc (arc 8) is added to Figure 3.9 from node 13 to node 11. Write the polygon/arc list for the new polygons and the left/right list for arc 8. Polygon 101 in Figure 3.9 will be replaced by two new polygons. Suppose the new polygons are numbered 105 and 106, with 105 on the left of arc 8 and 106 on the right. Polygon 105 consists of arcs 1 and 8, and polygon 106 consists of arcs 8, 4, and6.6. Explain the importance of topology in GIS.Topology is important in GIS for three reasons. First, it ensures data quality, such as lines meeting perfectly and polygons closed properly. Second, topology can enhance certain types of GIS analysis such as geocoding and traffic volume analysis. Third, topological relationships between spatial features allow GIS users to perform spatial data query.7. What are the main advantages of using shapefiles?Shapefiles have two main advantages over topology-based data such as coverages. First, shapefiles can display more rapidly on the computer monitor. Second, shapefiles are nonproprietary and interoperable, meaning that they can be used across different software packages.8. Explain the difference between the georelational data model and theobject-based data model.The object-based data model differs from the georelational data model in two aspects. First, the object-based data model stores both the spatial and attribute data of spatial features in a single system rather than a split system. Second, the object-based data model allows a spatial feature (object) to be associated with a set of properties and methods.9. Describe the difference between the geodatabase and the coverage in terms of the geometric representation of spatial features.The geodatabase is similar to the coverage model in terms of the geometric representation of simple features. The difference between the two models lies mainly in the composite features of regions and routes. The geodatabase does not support the region subclass and replaces the route subclass with polylines with m (measure) values.10. Explain the relationship between the geodatabase, feature dataset, and feature class.Geodatabase, feature dataset, and feature class form a hierarchical structure. A geodatabase can contain one or more feature datasets, and a feature dataset can store one or more feature classes that share the same coordinate system and area extent.11. Feature dataset is useful for data management. Can you think of an example in which you want to organize data by feature dataset?[For example, census data sets such as counties, census tracts, and block groups can be stored as feature classes in a feature dataset called census.]12. Explain the difference between a personal geodatabase and a file geodatabase.A personal geodatabase stores data as tables in a Microsoft Access database with the mdb extension. A file geodatabase, on the other hand, stores data in many small-sized files in a folder with the gdb extension. The file geodatabase has no overall database size limit (as opposed to a two-gigabyte limit for the personal geodatabase) and can work across platforms (e.g., Windows as well as Linux).13. What is ArcObjects?ArcObjects is a collection of objects, properties, and methods, which provides the foundation for ArcGIS Desktop.14. Provide an example of an object from your discipline and suggest the kinds of properties and methods that the object can have.[For polygon features such as timber stands and census tracts, they can all have the properties of extent (i.e., xmin, ymin, xmax, and ymax) and spatial reference (i.e., coordinate system). These polygon or area projects can also have the method for deriving the centroid (i.e., the physical center of a polygon).]15. What is an interface?An interface represents a set of externally visible operations of an object. To use the properties and methods of an object, we work through an interface that has been implemented on the object.16. Table 3.1 shows “must not overlap” as a topology rule for polygon features. Provide an example from your discipline that can benefit from enforcing this topology rule.[Esri maintains a data model website, where one can download discipline-specific data models (/datamodels). For example, one can download the Census Administrative Boundaries Data Model poster by clicking Case Studies for Census-Administrative Boundaries on the page. The poster includes many topology rules between many census-related feature classes.]17. “Must not intersect” is a topology rule for line features. Provide an example from your discipline that can benefit from enforcing this topology rule.[Esri maintains a data model website, where one can download discipline-specific data models (/datamodels). For example, one can download the Census Administrative Boundaries Data Model poster by clicking Case Studies for Census-Administrative Boundaries on the page. The poster includes many topology rules between many census-related feature classes.]18. The text covers several advantages of adopting the geodatabase. Can you think of an example in which you would prefer the geodatabase to the coverage for a GIS project?[The geodatabase data model provides a convenient framework for storing and managing GIS data under different themes such as census, transportation, and so on. Each of the themes is treated as a feature dataset in the geodatabase.]19. Compare Figure 3.19 with Figure 3.21, and explain the difference between the geodatabase and the coverage in handling the route data structure.A route subclass in a coverage is built on arcs and sections, and its linear measures are based on the lengths of arcs. A route in a geodatabase has its linear measures stored as the m values, along with x- and y-coordinates in the geometry field.20. Draw a small TIN to illustrate that it is a composite of simple features. [Draw a couple of nonoverlapping triangles, and mark nodes, lines, and areas on the drawing.]Chapter 4 Review Questions1. What are the basic elements of the raster data model?The basic elements of the raster data model are cell value, cell size, cell depth, raster bands, and spatial reference.2. Explain the advantages and disadvantages of the raster data model vs. the vector data model.The main advantage of the raster data model is having fixed cell locations, which make it easier for data manipulation, aggregation, and analysis. The main disadvantage is its weakness in representing the precise location of spatial features. Also, raster data such as satellite images have large memory sizes.3. Name two examples each for integer rasters and floating-point rasters. Examples of integer rasters are land use and soil types. Examples of floating-point rasters are precipitation and elevation.4. Explain the relationship between cell size, raster data resolution, and raster representation of spatial features.A larger cell size means a lower raster data resolution and greater difficulty in representing spatial features with cells.5. You are given the following information on a 30-meter DEM:• UTM coordinates in meters at the lower-left corner: 560635, 4816399• UTM coordinates in meters at the upper-right corner: 570595, 4830380How many rows does the DEM have? How many columns does the DEM have? And, what are the UTM coordinates at the center of the (row 1, column 1) cell? The DEM has 466 rows and 332 columns. The center of the (row 1, column 1) cell has the UTM coordinates of 560650, 4816414.6. Explain the difference between passive and active satellite systems.A passive system acquires spectral bands from the electromagnetic spectrum reflected or emitted from the Earth’s surface, whereas an active system provides its own energy to illuminate an area of interest and measure the radar waves reflected or scattered back from the Earth’s surface.7. Go to either the GeoEye website (/) or the DigitalGlobe website (/), and take a look at their very high resolution sample imagery.[Click on Gallery on the Space Imaging web page to view sample images. Click on Sample Imagery on the DigitalGlobe web page to view sample images.]8. What is a digital elevation model?A digital elevation model consists of an array of uniformly spaced elevation data.9. Describe three new data sources for producing DEMs.DEMs can be produced using (1) stereo optical satellite images, (4) stereo SAR images, (5) LiDAR data10. Go to the USGS National Elevation Dataset website(/about.html) and check the kinds of DEM data that are available from the USGS.Four kinds of DEM data are listed at the website: 1/9 arc-second (approximately 3 meters) resolution, 1/3 arc-second (approximately 10 meters) resolution, 1 arc-second (approximately 30 meters) resolution, and 2 arc-second (approximately 60 meters) resolution.11. Google the GIS data clearinghouse for your state. Go to the clearinghouse website. Does the website offer USGS DEMs, DRGs, and DOQs online? Does the website offer both 30-meter and 10-meter USGS DEMs?[Typically the information about USGS DEMs, DRGs, and DOQs is included on the page for data download.]12. Use a diagram to explain how the run length encoding method works.13. Refer to the figure below, draw a quad tree, and code the spatial index of the shaded (spatial) feature.14. Explain the difference between lossless and lossy compression methods.A lossless compression method allows the original image to be precisely reconstructed. A lossy compression method cannot reconstruct fully the original image but can achieve high-compression ratios.15. What is vectorization?Vectorization refers to the conversion of raster data into vector data.16. Use an example from your discipline and explain the usefulness of integrating vector and raster data.[A common example is use of digital orthophoto for display with vector data such as roads or for editing vector data such as digitizing new roads.]Chapter 5 Review Questions1. What is a geoportal?A geoportal offers multiple services, including links to data services, news, references, a community forum, and often an interactive data viewer.2. List the spatial resolutions of DEMs available from the National Elevation Dataset.They are 30 meters for 1 arc second, 10 meters for 1/3 arc second, and 3 meters for1/9 arc second.3. What kinds of data are contained in the USGS DLG files?The USGS DLGs include hypsography (i.e., contour lines and spot elevations), hydrography, boundaries, transportation, and the U.S. Public Land Survey System.4. What is SSURGO?SSURGO stands for Soil Survey Geographic database, a database compiled from field mapping at scales ranging from 1:12,000 to 1:63,360 by the Natural Resources Conservation Service for uses at the farm, township, and county levels.5. Suppose you want to make a map showing the rate of population change between 2000 and 2010 by county in your state. Describe (1) the kinds of digital data you will need for the mapping project, and (2) the website(s) you will use to download the data.[(1) One will need the population data for 1990 and 2000 and a digital county map. (2) One can get the population data for 1990 and 2000 from the U.S. Census Bureau website and the digital county map from a state clearinghouse.]6. Google the GIS data clearinghouse for your state. Go to the clearinghouse website. Select the metadata of a data set and go over the information in each category.[The metadata of a data set is usually included on the data download page.]7. Define "neutral format" for data conversion.A neutral format is a public or de facto format for data exchange. Data in a neutral format can be imported to different GIS packages.8. What kinds of data are contained in the TIGER/Line files?TIGER/Line files contain legal and statistical area boundaries such as counties, census tracts, and block groups as well as roads, railroads, streams, water bodies, power lines, and pipelines.9. Describe two common types of field data that can be used in a GIS project. Two important types of field data that can be used in a GIS project are survey data and global positioning system (GPS) data.10. Explain how differential correction works.Differential correction uses correction factors available from a reference (base) station to reduce noise errors of data collected by a GPS receiver. Reference stations such as those participating in the National Geodetic Survey Continuously Operating Reference System are located at points that have been accurately surveyed.11. What types of GPS data errors can be corrected by differential correction? Differential correction can correct noise errors, which include ephemeris (positional) error, clock errors (orbital errors between monitoring times), atmospheric delay errors, and multipath errors (signals bouncing off obstructions before reaching the receiver).12. What kinds of data must exist in a text file so that the text file can be converted to a shapefile?To be converted to a shapefile, a text file must have x-, y-coordinates, which can be geographic (in decimal degrees) or projected.13. What is COGO?COGO refers to coordinate geometry, a study of geometry and algebra that can provide the methods for creating digital spatial data of points, lines, and polygons from survey data.14. Suppose you are asked to convert a paper map to a digital data set. What methods can you use for the task? What are the advantages and disadvantages of each method?One can convert a paper map to a digital data set by using digitizing or scanning. Digitizing using a digitizing table is simpler because a GIS package typically has a built-in digitizing module for manual digitizing. This method is also preferred if the number of features to be digitized is small. Scanning uses the machine and computer algorithm to do most of the work, thus avoiding human errors caused by fatigue or carelessness. Scanning can also be more cost effective than manual digitizing for a large data producer.15. The scanning method for digitizing involves both rasterization and vectorization. Why?Rasterization converts a black-and-white map into a binary scanned file in raster format. Vectorization uses a process called tracing to turn raster lines into vector lines.16. Describe the difference between on-screen digitizing and tablet digitizing.On-screen digitizing is manual digitizing on the computer monitor. Compared to tablet digitizing, on-screen digitizing is more comfortable for the user. Another advantage of one-screen digitizing is that, during the editing process, the user can consult different data sources displayed on the screen.Chapter 6 Review Questions1. Explain map-to-map transformation.Map-to-map transformation is one type of geometric transformation that converts the newly digitized map into projected coordinates.2. Explain image-to-map transformation.Image-to-map transformation is one type of geometric transformation that converts the rows and columns (i.e., the image coordinates) of a satellite image into projected coordinates.3. An image-to-map transformation is sometimes called an image-to-world transformation. Why?An image-to-map transformation is also called an image-to-world transformation because the process converts a satellite image into real-world coordinates.4. The affine transformation allows rotation, translation, skew, and differential scaling. Describe each of these transformations.Rotation can rotate a map’s x-and y-axis from the origin. Translation can shift its origin to a new location. Skew can allow a nonperpendicularity (or affinity) between the axes, thus changing its shape to a parallelogram with a slanted direction. And differential scaling can change the scale by expanding or reducing in the x and/or y direction.5. Operationally, an affine transformation involves three sequential steps. What are these steps?Step 1: update the x- and y-coordinates of selected control points to real-world coordinates.Step 2: run an affine transformation on the control points and examines the RMS error. Step 3: use the estimated coefficients and the transformation equations to compute the x- and y-coordinates of map features in the digitized map or pixels in the image.6. Explain the role of control points in an affine transformation.The control points are used to estimate the coefficients of the affine transformation and to compute the root mean square (RMS) error. Therefore, the control points play a key role in the transformation process.7. How are control points selected for a map-to-map transformation?Control points are selected directly from the source map. A USGS 1:24,000 scale quadrangle map has 16 points with known longitude and latitude values: 12 points along the border, and 4 additional points within the quadrangle. These 16 points are potential control points for a map-to-map transformation.8. How are ground control points chosen for an image-to-map transformation? Ground control points (GCPs) are selected from a satellite image. GCPs are points where both image coordinates (in rows and columns) and real-world coordinates can be identified.9. Define the root mean square (RMS) error in geometric transformation.The root mean square (RMS)error measures the deviation between the actual (true) and estimated (digitized) locations of the control points. In other words, the RMS error measures the goodness of the control points.10. Explain the role of the RMS error in an affine transformation.The RMS error is a measure of the accuracy of an affine transformation. If the RMS error is within the acceptable range, then the assumption is that this same level of accuracy based on the control points can also apply to the entire map or image.11. Describe a scenario in which the RMS error may not be a reliable indicator of the goodness of a map-to-map transformation.Suppose the control points are located at the four corner points of a USGS quadrangle map. Even if the control points are shifted from their true locations, the RMS error remains unchanged as long as the object formed by the control points retains the shape of a parallelogram.12. Why do we have to perform the resampling of pixel values following an image-to-map transformation?Because the new image created from an image-to-map transformation has no pixel values, resampling must be followed to fill each pixel of the new image with a value or a derived value from the original image.13. Describe three common resampling methods for raster data.Three common resampling methods are nearest neighbor, bilinear interpolation, and cubic convolution. The nearest neighbor resampling method fills each pixel of the new image with the nearest pixel value from the original image. The bilinear interpolation method uses the average of the four nearest pixel values from three linear interpolations. And the cubic convolution method uses the average of the 16。

地理信息系统原理课后作业答案第1章绪论1 什么叫信息、数据？它们有何区别？信息有何特点？答：信息是客观事物的存在及演变情况的反映。

对于计算机而言，数据是指输入到计算机并能为计算机进行处理的一切现象（数字、文字、符号、声音、图像等），在计算机环境中数据是描述实体或对象的唯一工具。

数据是用以载荷信息的物理符号，没有任何实际意义，只是一种数学符号的集合，只有在其上加上某种特定的含义，它才代表某一实体或现象，这时数据才变成信息。

信息的特点：①客观性②适用性③传输性④共享性。

2 什么叫空间数据、地图？举例说明空间数据有哪几种类型。

答：空间数据是以点、线、面等方式采用编码技术对空间物体进行特征描述及在物体间建立相互联系的数据集。

地图是表达客观事物的地理分布及其相互联系的空间模型，是反映地理实体的图形，是对地理实体简化和再现。

空间数据主要有点、线、面三种类型。

例如，地图上的点可以是矿点、采样点、高程点、地物点和城镇等；线可以是地质界线、铁路、公路、河流等；面可以是土壤类型、水体、岩石类型等。

6 试述地理信息系统的组成及各部分的主要功能。

答：地理信息系统主要由四部分组成，即计算机硬件系统、计算机软件系统、地理空间数据和系统开发、管理和使用人员。

计算机硬件系统是地理信息系统的建立的保证。

计算机软件系统是指地理信息系统运行所必须的各种程序及有关资料。

主要包括计算机系统软件、地理信息系统软件和应用分析软件三部分。

地理空间数据是GIS的操作对象，是GIS所表达的现实世界经过模型抽象的实质性内容，地理空间数据实质上就是指以地球表面空间位置为参照，描述自然、社会和人文经济景观的数据。

人是地理信息系统中重要构成因素，GIS不同于一幅地图，需要人进行系统组织、管理、维护和数据更新、系统扩充完善、应用程序开发，并采用地理分析模型提取多种信息。

第2章空间数据结构1.什么叫像元、灰度值、栅格数据？答：将工作区域的平面表象按一定分解力作行和列的规则划分，形成许多格网，每个网格单元称为像素，即像元。