Have you ever seen a portrait where the face or eyes appear to follow your every movement? These are popular decorations at haunted houses that are typically based on the hollow face illusion. In this illusion your brain is tricked into perceiving a concave face (i.e. hollow or caved-in) as actually standing out like normal face.

Inspired by creepy face following portraits, I decided to put a modern spin on the classic illusion by using real-time face detection. You can see from the video above and the photo below the project I created using a Raspberry Pi and camera running code based on openFrameworks and OpenCV. Follow this guide to learn how I built this creepy face tracking portrait!