Accordingtothetopographyofmountains,thediscretedatapointsfrommapofthewholeregionarefirstsubpidedintosubregionswiththepointstakenfromthefeaturelinesofridge,valleyandscarpbeinginsertedintothemappointset,andusingthefeaturelinesastheboundariesofsubregionstobuildconstrainedDelaunayTIN.Suchanapproachhastheadvantagesofensuringhighaccuracyandfastspeedoflinelayout.
