Visibility and Urban Activity Location: The Small-World and Scale-Free Properties of Urban Visuospatial Networks

摘要

Theeconomicperformanceofarangeofurbanactivitiesreliesonextensiveexposuretopedestrians.Successinattractingmeanderingpedestrianstoaparticularlocationdependsonthemeansbywhichtheyprocessvisuospatialinformation.Inthispaper,weproposeanoriginalmethodforanalyzingthevisuospatialintegrationofparticularlocationswithinastreetnetwork.Asanexampleweanalyzethedistributionofoneurbanactivity-foodanddrinkpublicfacilities,whichareamongthemostprobablenavigationaltargetsforpedestriansinacasestudyarea.Theseactivitiesareobjectsofnavigationaldecisionsthatwerepresentasvisibilitygraphs(ornetworks).Wecreatedthreegraphs:astreetnetworkvisibilitygraphandtwofunctionalvisibilitygraphs.Onefunctionalgraphisbasedontheexisting,“natural”distributionofurbanscape.Anothergraphrepresentsasyntheticversionoftheenvironment.Wecomparedthegraphs’globalnetworkpropertiesassmall-world,andscale-freemodels.Whileallthegraphsexhibitedsmall-worldproperties,onlythe“natural”functionalgraphwasscale-free.Inessence,thedistributionofviewsavailableforanurbantravelerintheexistingsettinghadaparticularstructure,withnumerousweaklyconnectedlocationscoexistingwithasmallnumberofhubsandwithanexceptionallylargenumberofvisualconnections.Theresultsshowthatexistingurbanvisuospatialnetworksharemorphologicalsimilaritieswithothernaturalnetworks,suggestingthatcommonorganizationalprinciplesunderlienetworkstructure.