PURPOSE: To eliminate the need of inspecting whether the line of sight crosses boundary by selecting the constitution face of a polyhedron, which makes the boundary of and area an faces in the direction of the line of sight and executing sorting based on a distance with the eyes.
CONSTITUTION: A boundary face facing in the direction of the line of sight is sorted or the boundary face facing in the opposite direction to the line of sight is stored. Picture groups on a projection face, which correspond to the boundary face, are decided by a scan conversion 3 in a sorting order. A luminance value is calculated until a system goes out a volume data area along the eyes passing through them so as to decide the value of a picture element. When the volume data area is concave, the system once enters the volume data area again after it goes out the volume data area. Similar calculation is executed on the boundary of an entering position and it is accumulated in a previous value. Thus the precise luminance value can be calculated. It is not necessary to inspect whether the line of sight crosses the boundary or not only by using the scan version 3 in a boundary face unit.
DOI AKIO
UNO SAKAE
