A technique to improve the tracking of initial and terminal position of trace particles for particle tracking velocimetry (PTV) is presented. In this system, three separate images of the trace particles at their initial and terminal positions, and along their pathlines are made using a color TV camera and three RGB lights, and are stored separately as R- and G- and B-images. Using the green image of the trace-particle pathlines, the pair of trace-particle images at the initial and terminal position is determined that overlaps the endpoints of each pathline image, and velocity vectors are calculated. This system was used to measure the movement of white artificial tracers painted on two counter-rotating tables. Despite the fact that the two groups of tracer to move in opposite directions on the measuring-field plane, correct velocity vectors of all trace particle images were obtained.
