By default Blender's Object Index passes are white only. This works fine for internal compositing but isn't very useful when you intend to do post work in an image editor (GIMP/PS).
This node group will add colours to your different pass indices (is that how you spell that?) and output the image to a file. Now when editing the final render in GIMP/PS, include this file as a layer to "select by color" the objects you'd like to isolate..
Hi Trimondi,
Take a look at this brief explanation: http://youtu.be/dvTImYO0AH8
hope this helps to clarify:)
Oh BTW if you need more explanation of render passes you can start by going here: http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Passes
and I almost forgot to mention.. this blend may appear incorrectly pre 2.62 since the mesh editing system, bmesh, has been implemented in 2.62.
Hi ! its amazing node but its limit is set to till 4 object indexes, what will happen if we have 50 or mode different objects in the scene and want all random index pass ?
it seems interesting...could you explain better? Sorry for my ignorance, but I'm new in blender...