Medical and industrial needs exist to track the position, volume and geometry of moving objects whose shapes change. Video imaging offers frame rates of sufficient frequency to support real-time sensing of fairly rapid changes in the real world. It is the processing of the video frames which represents the bottleneck in a "real- time" implementation. However, under certain limiting constraints, namely near-symmetry around a curved axis, real-time measure- ments are feasible with standard PC-based software to obtain 3-D positions, shape and volume of a moving and changing 3-D object. The paper describes a novel stereo-photogrammetric analysis system based on object silhouettes. Implementation involves the end-to-end system from video cameras to user interface and reporting of results. A medical application's scenario puts high demands on robustness and simplicity of the user interface, while operating in an entirely automated fashion. "Real-time" represents the need to process an image pair each 2 seconds. Accuracies of Ã‚Â±1% in dimension and 3% in volume are required and permit one to accept certain shortcuts in the photogrammetric approach.
R. Wilson, R. Wilson,
"Real-time close-range 3D non-contact volume and motion measurements", Proc. SPIE 1395, Close-Range Photogrammetry Meets Machine Vision, 139505 (1 August 1990); doi: 10.1117/12.2294248; https://doi.org/10.1117/12.2294248