Back face detection technique

Question

Describe the Back face detection technique in short? Also describe its features?

Answer 1

a) Fast and easy object space technique.

b) For recognizing the back faces of the polyhedron.

c) Mainly based on inside-outside test.

d) Use plane parameters A, B, C, D: Ax +By+ Cz +D < 0

e) Inside point is all along the line of sight to surface: V.N = Vz C

f) The polygon is back face when C < 0

g) Polygon can’t see on any face when C = 0

h) The Z component value: C <= 0