GT_PLANARPOLY (GeoTools -> Drawing Cleanup -> Make polylines/3dfaces planar): The GT_PLANARPOLY command is used to make a polyline or 3dface planar. A planar polyline or 3dface is one in which all the vertices can be placed on a single plane. Generally, this is possible only if all the vertices have the same elevation or, in the special case of a 4-vertex polyline, the polyline can be considered planar if two pairs of adjacent vertices have the same elevation. The GT_PLANARPOLY command makes this happen by setting the elevations of adjacent vertices same if they are within a specified tolerance. The need to create perfectly planar polylines or 3dfaces is often required and useful in photogrammetry data capture and rendering applications.