Line method for visible surface detection

Question

Describe in brief the line method for visible surface detection?

Answer 1

Scan line technique deals with multiple surfaces. As it executes each scan line at a time, and the entire polygon intersected through that scan line are observed to find out which surfaces are observable. The visibility test comprises the comparison of depths of each overlapping surface to find out which one is nearer to the view plane. When it is found so, then it is declared as a visible surface and the intensity value at the positions along the scan line are centered into the refresh buffer. Scan line way takes the following suppositions:

i) The plane of projection is z = 0 plane.
ii) The orthographic parallel projection.
iii) The direction of projection, d = (0, 0, -1)
iv) Objects build up of polygon faces.