Distance image
Distance images are pictorial representations of distances of an entire scene. This is in contrast to normal images, which show gray levels or color values of the objects, or temperature images (representation of surface temperatures) or false color images (e.g. infrared images).
Distance images are primarily used in technology for measurement or control. They can be calculated using a wide variety of technical systems:
Real-time systems
- Stereo systems: the surroundings are recorded with two cameras ( stereo photogrammetry ) and the distance to objects is calculated using correlation functions;
- Triangulation systems : a light source maps a certain pattern onto the object. A camera records this pattern from a different angle and calculates the distance from the distortion ;
- TOF cameras , whichinfer the distance by measuring the transit time of the light.
Scanning systems
- Laser scanner in whichthe distance for a point is measuredusing a modulated laser beam (see time of flight measurement). Then the laser is deflected a little using a mirror and the next point is measured. So the picture builds up little by little.