Motion distortion occurs when an image is progressively scanned by a camera at a slow scanning speed. With a film camera this can be done by using a slit shutter near the film plane. With a digital camera this can be done using a slow rolling shutter or slow progressive-scan imager.
When the subject moves during a slit-scan exposure parts of it will appear lengthened, shortened, or inverted depending upon the speed of its movement relative to the speed of the slit or scan line. This "property" of the effect can be exploited in predictable ways, as in the photo below right, or in unpredictable or random ways.
Using a slit-scan or progressive-scan camera, when the camera moves the background becomes distorted as well. But using Digital Air's camera systems, which don't actually move, the background and static objects in the scene appear perfectly normal. Only moving subjects, such as people in the shot, appear distorted. Of course if the camera array is moved during the exposure both will appear distorted (albeit differently).
This effect can also be time-progressive (the example below is a frozen moment).
This example of motion distortion was recorded with 32 HD-1 digital cameras recording full frame uncompressed HD images synchronously at 30 fps. The slit scan shutter effect was then interpolated over several seconds of recording time.