How do I bake a transparent shadow texture using Cycles bake? I'm trying to bake a transparent png image with Cycles. It drives me crazy trying to work out how to do this. Can anyone guide me how to accomplish it, or is it possible at all?

White background


Transparent background
As far as I know it's not possible to bake images with transparency in Cycles, but it's possible to figure out some workarounds, depending on what you want to achieve.

To bake a transparent shadow texture:


Set up your scene. I'll just use a simple tree in my example. Place a plane under your objects and scale it big enough to catch all the shadows.


Create a new image in the UV/Image Editor and unwrap the plane.


Create a simple diffuse material for the plane. Add an Image Texture node to the material and select the new image you just created.


In the Render Panel set Samples to a nice number (depending on your scene) and set Bake Type to Shadow.


Bake the image. You should have something like this:


Go to Compositing, select Use nodes and delete the default nodes. Then set up the nodes like this:


In the UV/Image Editor select Viewer Node from the drop down list.


Save the image as an RGBA file (*.png, *.tga - whatever you need).


Your baked transparent shadow texture is ready.