Image Space Approach -Approaches for visible surface determination

The initial approach as image-space, determines that of n objects in the scene is visible at every pixel in the image. The pseudo-code for such approach as like:

           for(each pixel in the image) 

           {

               determine the object closest to the viewer that is passed by the projector through the pixel;

                draw the pixel in the appropriate color;

            }

This approach needs examining all the objects means to find out which is closest to the viewer besides the projector passing via the pixel. It is, in an image-space algorithm, the visibility is certain point by point at each pixel location on the projection plane. Effort is proportional to n.p., if the number of objects is 'n' and the pixels is 'p'.