www.colacola.se - 3D models and renders by Anders Lejczak
Mini tutorial
How to (easily and seamlessly) add a backgound image to your render in post without worrying about tricky stuff like semi transparent areas or motion blurred parts.

You need:
  • Photoshop
  • A rendering program that can output alpha passes (for example Cinema4D, Modo or basically any decent 3D/Rendering package)