GEOSを整理してみた

GIS

勉強がてらGEOSライブラリのジオメトリ生成部分の機能を図にまとめてみました。
SymmetrucDifferenceが怪しいので、解る方がいたら教えて下さいませ。
*1


virtual Geometry * convexHull () const
Returns the smallest convex Polygon that contains all the points in the Geometry.

virtual Geometry * intersection (const Geometry *other) const
Returns a Geometry representing the points shared by this Geometry and other.

virtual Geometry * Union (const Geometry *other) const
Returns a Geometry representing all the points in this Geometry and other.

virtual Geometry * difference (const Geometry *other) const
Returns a Geometry representing the points making up this Geometry that do not make up other.

virtual Geometry * symDifference (const Geometry *other) const
Returns a set combining the points in this Geometry not in other, and the points in other not in this Geometry.

http://mathworld.wolfram.com/SymmetricDifference.html

http://geos.refractions.net/


1/11追記


こちらに丁寧な説明があるようです、調べるまでも無かった模様 orz...
３）空間解析の基礎　（空間演算処理）
http://web.sfc.keio.ac.jp/~asaka/gis_notes/gis_av8/man3.htm

*1:図形の形が解りにくいので全体的に怪しいと言う気もする