Stephens RS 1989 : A system for tracking the three dimensional motion of objects in real time is described. The system uses a technique of localized image access that enables it to achieve frame-rate operation without the need for any special purpose hardware. All the processing for one camera can be performed on a network of five transputers, with a single transputer combining the information from several cameras. A dynamic Hough transform is used to solve a set of contraints derived from image measurements. I shall demonstrate how the robustness and intrinsic parallelism of the Hough transform can be put to practical use. The system has been tested on a stored sequence of one hundred image pairs, which were captured under realistic, noisy conditions, and the results are presented here.