Multi-View Render

Suppose that you desire to render two scenes into a single image (render).  This normally can be done in photoshop, or if it's a video, a video compositor.  However, if for some reason you want to do it all in Blender, it can be done.

For this entry we'll explore how to take the two following scenes:

...and render them into a single image side by side.  This approach can be used for stereoscopic rendering, or to do a dual view render, or just to combine two different scenes in a juxtaposed fashion.

The key to this method is to first have two separate scenes.  Have a quick look at this entry [Intro to Scenes]   if you aren't familiar with working with scenes.  

What's nice about this approach is that you can have one scene rendered with Cycles, and the other with the Internal renderer.  Once both scenes are created and populated, all the work is done in the compositor.

The image below shows the final node setup:

Essentially what is happening is that each Render Layer has a different Scene.  Each scene is first cropped with the Distort > Crop node.  Relative allows you to work with percentages rather than pixel sizes.  In this case, I took the left half of the top Render Layer, and the Right half of the "text" Render Layer.

Depending on how you crop you may or may not need to Distort > Translate each image.  Since I cropped my images in place, I didn't need to translate, but I put the nodes in there just to show where they would go.

Finally, both branches can be joined with a Color>Mix node set to Screen.  The result is the final image, of two renders side by side.