To render an image for use with red & blue 3d glasses, the usual way to do it is to render from one point of view, convert it to a single intensity (greyscale) value per pixel, and then put that into the red color channel. Render from a slightly different point of view, convert that to greyscale again and put that into the blue channel.
This can be prohibitive when rendering a single time is already very costly.
Are there any methods by which you could take a single render, and corresponding depth buffer, and come up with something suitable for both red and blue channels?