I am trying to create a an image of an object (say a cube) and its shadow, with any other pixel except for the object and shadow being transparent, in Blender 2.7. I need this since I will place the resulting images next to several others in Photoshop later, and also as standalones, in a scientific paper which requires that all images have a transparent background.

I know this question has been asked many times before, but all the answers I found are lacking, namely: this question is similar, but the answer uses a "shadow" output of the layer which I couldn't find (I assume it doesn't exist in 2.7?). On the other hand, this video gives a nice solution in case you are trying to place your objects + shadows on top of an existing image by multiplying outputs, but does not produce an image with a transparent background, and I don't see a way to modify it easily.

  • 2
    $\begingroup$ The shadow pass does exist in 2.7. $\endgroup$ – gandalf3 Jul 4 '14 at 20:31
  • $\begingroup$ Related: blender.stackexchange.com/a/5160/599 $\endgroup$ – gandalf3 Jul 4 '14 at 20:55
  • $\begingroup$ @gandalf3 Thanks, I am quite new to blender, I didn't figure you could add a "shadow" output. I now went to the layers dialogue and ticked the "shadow" tickbox. This added the "shadow" output to the render-layer node, but inspecting it I see that it is simply zero everywhere. Am I still missing something? $\endgroup$ – olamundo Jul 4 '14 at 21:18
  • 1
    $\begingroup$ Mesh lights won't cast shadows, see blender.stackexchange.com/q/5416/599 $\endgroup$ – gandalf3 Jul 4 '14 at 21:19
  • $\begingroup$ @gandalf3 Great diagnosis based on symptoms only. you should be a doctor :) Thanks! You prefer to answer this or close it as yet another duplicate? $\endgroup$ – olamundo Jul 4 '14 at 21:21