Locate your black and white pixel image. This is your marker. If you do not already have a marker card, print one out at home. Protect your marker, as this will be the key to revealing the secret 3D image. Turn your webcam on and position yourself in front of the webcam. Hold the marker so that the black and white pixel image faces the webcam. Watch as both you and the marker appear on your screen. Instantly, the marker on your screen is replaced by the surprise 3D image! Use your hands to move and rotate the marker, and watch as the image moves on your screen. You have entered into the interactive world of Perseus right before your eyes!