Some 3d stereo player for auto-stereoscopy vision needs of a depth map.
What is?
It is a 255 gray scale image that contains information relating to the distance of the surfaces of scene objects from a viewpoint.
In our case we make this image with in objects closest are clearer.

It’s used for generate intermediate images from Left to Right.

The picture below shows the depth map shader’s nodes. I have automatized the  create process with a ptyhon class.

This shader define the Zero Plane in the area 128,128,128 of the gray scale.

Then the object’s point closest to the camera is in the area 255,255, 255 and so on.