How to Render Alpha Image?

I should know this, but how do I render an alpha map of my image. I selected “Straight alpha” from the options but it rendered the shading too (see second image from top) and i only want the outline of my object like in the bottom image. How do I do this?

Select ''shadeless" in the material buttons

Use the node editor and connect the alpha channel of the render layer to the image channel of the composite output node.

Thanks Midel. Very helpful. :slight_smile: It seems there’s a lot to set up: I also needed to deselect a number of options in the render settings too to get this to work and make my objects material all white, whereas in other apps like “Vue” you just need to select 1 button “Render Alpha” and its good to go.

Do you know if there is an easier way to set this up in Blender so there’s not so many steps?


This is all that you need in the node editor. I made no other changes to the render settings.

JDep, thank you very much. I saw this only after posting my last reply! :slight_smile:

Thanks Richard. The screenshot is very helpful for us left brained types. :slight_smile: