Setting Up the Scene

Before you start compositing, you need to know what to do first. In our example, there is something that obviously stands out: you need the floor to go away, but you want to keep the shadows it receives from the character so you can composite on top of the real footage.

It’s really simple to do that in Blender Render because there is a setting for the materials that allows you to include an object that only receives shadows while the object itself will be transparent.

Just try it: create a new material for the floor, but in the Properties Editor on the Shadows panel of the Material tab, enable Shadows Only. Also, under Shadows Only, you’ll see a drop-down list: select the option Shadow Only instead of Shadows and Distance. If you launch a render now, you’ll see that the floor is not rendered, but the shadows Jim creates are there!

You can also go to the World tab in the Properties Editor and enable Ambient Occlusion. Set it to Multiply Mode and, in the Gather panel, increase the Samples to about 10, so the AO has more quality and less noise.

You could take a render now, put the footage behind Jim’s figure, and the scene is done! But we’re going to complicate the scene a little more. This way, you’ll have more control over the individual parts of the render and, therefore, over the resulting image and you’ll learn more about compositing with nodes.