“…The first group includes several typical works [8,24] on 2D spatial data. The second one consists of [2,3,4,5,7,9,10,11,13,14,15,17,18,19,20,22,27], which approach the handling of 3D objects in many aspects as follow. References [2,7,10,19,20,27] consider only 3D graphical data.…”