User:Kku/Concave hull

In computer graphics and geographic information systems, a concave hull of a set of points in space is a region enclosing the points which, can be concave. This is in contrast to the convex hull which is always a convex set. As such it may be a better representation of the area or volume spanned by the points than the convex hull.

Unlike the convex hull, a concave hull is not unique for a given set of points. It can depend on the algorithm used and the tolerances of the algorithm, such as for how jagged its outline is. It should always be no bigger than the convex hull though. Predefined routines or commands for computation of a concave hull exist in common GIS systems, e.g. SDO_GEOM.SDO_CONCAVEHULL in Oracle Spatial, ST_ConcaveHull in PostGIS, v.concave.hull in GRASS GIS, and lasboundary in LAStools.