Depth Cueing

Depth Cueing

Hidden surfaces are not removed but displayed with different effects such as intensity, color or shadow for giving hint for third dimension of the object. It is called depth cueing.

Hidden surface

A set of 3 D surfaces are to be projected onto a 2 D screen. To identify those parts of a scene that are visible from a chosen.  Viewing position, Correct visibility when multiple opaque polygons cover the same screen space,
only the closest one is visible.

Goal : Determine which surfaces are visible and which are not.
Other names:
Visible surface detection
Hidden surface elimination

Display all visible surfaces, do not display any occluded surfaces.

Need of hidden surface removal

To save time, draw only surfaces we see

When we view a picture containing non transparent objects and surfaces, then we
can’t see those objects from view which are behind from the objects closer to eye.
We must remove these hidden surfaces to get realistic screen image.
The identification & removal of these surfaces is called the Hidden surface
problem.
Active research subject lots of algorithms have been proposed in the past (and is still a hot
topic).