chapter  16
19 Pages

Map generalisation

Ofallthetasksfacedincomputercartographyand GIS,fewaresofundamentaltotheprocessofmap makingandsodifficulttoautomateasthatofgeneralisation.Becauseamapisanassemblageofgraphic symbolsthatpresentaviewofsomeaspectofour understandingoftheworld,itisnecessarilyan abstractionofknowledge.Itisnotsimplyacollection offacts,ratheritisacaricatureofthesefactswhich, intheirtransformationtomapsymbols,assistthe mapreadertounderstandspatialformandstructure andtodistinguishimportantcharacteristicsofthe phenomenathatarerepresented.Theprocessofgeneralisationrequirestheselectionofthosefeatures thatareessentialtothemap'spurposeandtherepresentationoftheminawaywhichisclearand informative.Bothselectionandrepresentationcanbe expectedtoinvolveadegreeofinformationreduction relativetowhatisknown.Amajorconstrainttothe informationcontentofamapisthescale,insofaras itdictatesthespaceavailableformapsymbols.Thus mapgeneralisationmayberegardedasascale-dependentprocessofinformationabstraction.