Ghostly pictures made in 3D – minus the camera
[Philip Lelyveld comment: The video has weirdly beautiful techno music. ]
Ghost imaging was developed because it can take pictures of objects by recording light that doesn't actually hit them, making it promising for surveillance.
...a projector shines hundreds of random computer-generated, black-and-white patterns on an object, while four single-pixel detectors record the amount of light reflected back. Patterns that happen to match the shape of the object reflect more light than those that don't. The computer weights each black-and-white pattern according to the intensity recorded by the detectors and overlays the results, so that a picture of the object gradually emerges.
The 3D system's four detectors are placed above, below and on either side of the projector. These detectors measure slightly varying intensities of reflected light and create pictures with different shading.
REad the full story here: http://www.newscientist.com/article/dn23552-ghostly-pictures-made-in-3d--minus-the-camera.html