Multi-LevelInteractioninParametricDesign
RobertAish1andRobertWoodbury2
1BentleySystems,Incorporatedrobert.aish@bentley.com2SimonFraserUniversity,SchoolofInteractiveArtsandTechnology,14thFloor,CentralCityTower,13450102Avenue,Surrey,BC,CANADA,V3T5X3rw@sfu.ca,WWWhomepage:http://www.siat.sfu.ca
Abstract.Parametricdesignsystemsmodeladesignasaconstrainedcollectionofschemata.Designersworkinsuchsystemsattwolevels:def-initionofschemataandconstraints;andsearchwithinaschemacollec-tionformeaningfulinstances.Propagation-basedsystemsyieldefficientalgorithmsthatarecompletewithintheirdomain,requireexplicitspeci-ficationofadirectedacyclicconstraintgraphandallowrelativelysimpledebuggingstrategiesbasedonantecedentsandconsequents.Therequire-menttoorderconstraintsappearstobeusefulinexpressingspecificde-signerintentionsandindisambiguatinginteraction.Akeyfeatureofsuchsystemsinpracticeappearstobeaneedformultipleviewsontothecon-straintmodelandsimultaneousinteractionacrossviews.Wedescribeonemultiple-viewstructure,itsdevelopmentandrefinementthroughalargegroupofarchitecturepractitionersanditsrealizationinthesystemGenerativeComponents.
1Architecturalpracticeandparametricdesign
ConventionalCADsystemsfocusdesignattentionontherepresentationofthe
artifactbeingdesigned.Currentlyindustryattentionisonsystemsinwhicha
designedartifactisrepresentedparametrically,thatis,therepresentationadmits
rapidchangeofdesigndimensionsandstructure.Parameterizationincreases
complexityofbothdesignertaskandinterfaceasdesignersmustmodelnotonly
theartifactbeingdesigned,butaconceptualstructurethatguidesvariation.
Parameterizationhasbothpositiveandnegativetask,outcomeandperceptual
consequencesfordesigners.Positively,parameterizationcanenhancesearchfor
designsbetteradaptedtocontext,canfacilitatediscoveryofnewformsandkinds
ofform-making,canreducethetimeandeffortrequiredforchangeandreuse,
andcanyieldbetterunderstandingsoftheconceptualstructureoftheartifact
beingdesigned.Negatively,parameterizationmayrequireadditionaleffort,may
increasecomplexityoflocaldesigndecisionsandincreasesthenumberofitems
towhichattentionmustbepaidintaskcompletion.
ParametricmodelinghasbecomethebasisformostmechanicalCADsystems
andnowisbeginningtoemergeasatoolforarchitecturaldesign.Whilethereis
ageneralappreciationoftheconceptsandadvantagesofparametricmodeling,applicationtoprojectsatthescaleandcomplexityofbuildingsraisesimpor-
tanttheoreticalandpracticalissues.Inadeepsense,parametricmodellingis
notnew:buildingcomponentshavebeenadaptedtocontextforcenturies.What
isnewistheparalleldevelopmentoffabricationtechnologythatenablesmass
customization.Buildingcomponentscanbeadaptedtotheircontextandpara-
metricmodellingcanrepresentbothcontextandadapteddesigns.Inadesign
marketpartlydrivenbynovelty,theresultingabilitytoenvisionandconstruct
newarchitecturalformsrewardsfirmshavingsuchexpertise.Therearerela-
tivelyfewsuchfirms,mostofwhichhavehadlongexperienceandhavebuilt
substantialreputationsondistinctiveformandconstruction.Butmanyfirms
andstudents(futurepractitioners)areinterested.Theconfluenceoftechnology
andinterestappearsasexplorationinanewdesignspace:architectureandits
supportingtechnologiesofparametricdesignandfabricationareexperiencing
bothco-developmentandrapidchange.
EmblematicofthischangeistheSmartGeometrygroup.Itcomprisessenior
practitioners,aCADsystemdeveloperandacademics.Itswebsiteleadswith
thedeclaration:
Architectureisfundamentallyaboutrelationships.Manyofthosere-
lationshipsaregeometricinnatureorfindageometricexpression.The
SmartGeometrygrouphasbeencreatedinthebeliefthatComputer
AidedDesignlendsitselftocapturingthegeometricrelationshipsthat
formthefoundationofarchitecture....Thegroupisdedicatedtoeducat-
ingtheconstructionprofessionsinthenewskillswhichwillberequired
tousethesenewsystemseffectively....Thegroupconductsaseriesof
schoolsandseminarswherethisnewtechnologyisexploredinthecon-
textofhighlyexperiencedprofessionals.(Minorverbtensechangesmade
tothequotation.)(www.smartgeometry.org)
Todate,severalsuchworkshopshavebeenconductedandworkshoppartici-
pantshavecontinuedtodevelopbothdesignsandideasforneededsystemsup-
port.Theoutcomesoftheworkshopsandworkthatfollowsfromthemcomprise
designs,someintendedforactualconstruction,someasexplorationsofdesign
possibility.Figures1and2showworkdonebytwoworkshopparticipants.
SmartGeometryworks,asitmust,throughusing(anddeveloping)systems
thatsupportdesignrelationships.Muchofitsworkparallelsandisinfluenc-
ingthedevelopmentoverthelasteightyearsofaspecificparametricdesign
systemGenerativeComponents(GC)byBentleySystems,Inc.Theprimaryde-
signeranddeveloperofGCisRobertAish.Atthetimeofwriting,GCwasnot
onthecommercialmarketanditsdevelopmentpathlayoutsideoftheBent-
leyproductprocess.Itsdesignanddevelopmenthavebeenextensivelyaffected
bymembersoftheSmartGeometrygroup,theprofessionalmembersofwhich
haveactedlargelyinadditiontotheirprofessionalrolesinsidetheirrespective
firms.Academicsandgraduatestudentshavebeeninvolvedindesign,review
andtrialworkshopstoanextentunusualforacorporateproject.Theexistence
ofamotivatedindependentusercommunityandarelativelyopenandrelatively
