Hidden Surface elimination: Depth Buffer or Z Buffer Algorithm

Depth buffer algorithm, developed by Catmull, is used to eliminate hidden surfaces. In this algorithm surface depths at each pixel position are compared.

1) Initialize Z buffer and frame buffer for all buffer positions.
Z- buffer (x,y) = 0 and frame buffer (x,y) = Ibackground
2) During scan conversion, for each position on each polygon surface compare depth values to previously stored values in depth buffer for determining visibility.
Calculate Z value for each position (x,y) for the polygon.
If z > Z buffer (x,y) then set
Z-buffer (x,y) =z, frame buffer (x,y) = Isurface (x,y)
3) Stop

Here, Ibackground = background intensity
Isurface = projected intensity


1) Can be implemented in hardware.
2) Easy to process.
3) It processes one object at a time.


1) It takes too much time to process.
2) Requires too much memory to process.

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