Function spatialite_sys::gaiaConcaveHull

pub unsafe extern "C" fn gaiaConcaveHull(
    geom: gaiaGeomCollPtr, 
    factor: f64, 
    tolerance: f64, 
    allow_holes: c_int
) -> gaiaGeomCollPtr

Concave Hull

\param geom pointer to input Geometry object. \param factor multiplier used for filtering Delaunay triangles: please read the note. \param tolerance optional snapping tolerance. \param allow_holes if FALSE any interior hole will be suppressed.

\return the pointer to newly created Geometry object (always of the Polygon type): NULL on failure. \n NULL will be returned if any argument is invalid.

\sa gaiaConcaveHull_r, gaiaFreeGeomColl, gaiaDelaunayTriangulation

\note This function will first create the Delauany Triangulation corresponding to input Geometry, determining at the same time the \b standard \b deviation for all edge's lengths. \n Then in a second pass all Delaunay's triangles will be filtered, and all triangles presenting at least one edge longer than \b standard \b deviation \b * \b factor will be discarded. \n All filtered triangles will then be merged altogether so to create the Concave Hull.

\note you are responsible to destroy (before or after) any allocated Geometry, this including any Geometry returned by gaiaConcaveHull()\n not reentrant and thread unsafe.

\remark \b GEOS-TRUNK support required.