▁from ▁the ▁rest , ▁and ▁is ▁scale d ▁while ▁maintain ing ▁the ▁area ' s ▁shape . ▁This ▁method ▁of ▁cart ogram ▁creation ▁is ▁sometimes ▁referred ▁to ▁as ▁the ▁project or ▁method ▁or ▁scale d - down ▁regions . ▁ ▁Cart og rams ▁may ▁be ▁class ified ▁also ▁by ▁the ▁properties ▁of ▁shape ▁and ▁topology ▁pres ervation . ▁Class ical ▁area ▁cart og rams ▁( sh own ▁on ▁this ▁page ) ▁are ▁typically ▁dist ort ing ▁the ▁shape ▁of ▁spatial ▁units ▁to ▁some ▁degree , ▁but ▁they ▁are ▁strict ▁at ▁pres erving ▁correct ▁neighborhood ▁relationships ▁between ▁them . ▁Sc aled - down ▁cart og rams ▁( from ▁the ▁NY ▁Times ▁example ) ▁are ▁strictly ▁shape - pres erving . ▁Another ▁branch ▁of ▁cart og rams ▁introduced ▁by ▁Dor ling , ▁rep laces ▁actual ▁shapes ▁with ▁circles ▁scale d ▁according ▁to ▁the ▁mapped ▁feature . ▁Cir cles ▁are ▁distributed ▁to ▁res emble ▁the ▁original ▁topology . ▁Dem ers ▁cart ogram ▁is ▁a ▁variation ▁of ▁Dor ling ▁cart ogram , ▁but ▁it ▁uses ▁rect angles ▁instead ▁of ▁circles , ▁and ▁attempts ▁to ▁retain ▁visual ▁c ues ▁at ▁the ▁exp ense ▁of ▁minimum ▁distance . ▁Sch ematic ▁maps ▁based ▁on ▁quad ▁trees ▁can ▁be ▁seen ▁as ▁non ▁shape - pres erving ▁cart og rams ▁with ▁some ▁degree ▁of ▁neighborhood ▁pres ervation . ▁ ▁A ▁collection ▁of ▁cont igu ous ▁area ▁cart og rams ▁is ▁available ▁at ▁World ma pper , ▁which ▁was ▁started ▁by ▁a ▁collabor ative ▁team ▁of ▁research ers ▁at ▁the ▁Univers ities ▁of