Track particles in videos to calculate an estimate of their velocity.
Particle tracking velocimetry (PTV) is a velocimetry method, i.e a technique to measure velocity of particles. The name suggests that the particles are tracked, and not only recorded as an image as it is suggested in another form, particle image velocimetry. There are two very different experimental methods: * the two dimensional (2D) modification of Particle Image Velocimetry (PIV), in which the flow field is measured in the two-dimensional slice of the flow, illuminated by a laser sheet (a thin plane) and low density of seeded particles allow for the tracking each of them individually for several frames. * the Three-Dimensional Particle tracking velocimetry (3D-PTV) is a distinctive experimental technique, based on multiple camera-system, three-dimensional volume illumination and tracking of flow tracers (i.e. particles) in three-dimensional space by using photogrammetric principles.