Particle tracking velocimetry (PTV) is a well-known technique for the determination of velocity vectors of flow within an observation volume. However, for a long time it was rarely applied because of the intensive effort necessary to measure coordinates of a large number of flow marker particles in many images. With today's imaging hardware in combination with the methods of digital image processing and digital photogrammetry, however, new possibilities have arisen for the design of completely automatic particle tracking velocimetry systems.