Output file different from preview I use Cycles renderer and nodes to output the image, normals and UVs at the same time. Here is what it looks light.


The preview in the RenderLayers node is what I expect (world positions).

However, when I press F12, in the Image file (Image0000.exr for the frame 0, etc), I get this :


instead of the expected result :


(I think that in the first image the cubes are here, they're just the same colour as the plane).

The preview gives me the correct image but the output is wrong. And if I press the Animation button, the result is correct in the files 0000.exr, etc, but wrong in Image0000.exr, etc.

Am I missing something? Is there a problem in my nodes ?

Thank you for your help! 



Thanks for the advice for using backdrop to debug, I figured out that it is the alpha node that was problematic :




Could someone explain to me how this alpha node works ? Apparently I got it completely wrong.
I'm not sure what you want the alpha over node to be doing there, but it's whats causing the white output.

Something as simple as this should work:



Example .blend