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We present a novel approach to 4D (XYZ + time) body scanning, developed for supporting medical rehabilitation monitoring. The system reflects the actual requirements for 4D measurements, providing a feature of capturing up to 120 Hz sequences of point clouds, with a spatial resolution of 1.0 mm and inaccuracy of 0.5 mm. The presented system consists of four directional modules arranged evenly around the measurement volume to provide complete scans. A structured light method is utilized, therefore each directional module consists of detectors and projectors. In order to enhance body surface coverage from every direction each measurement module uses two detectors and a single projector. This configuration is a result of optimizing the best scanning results considering proper amount of data and a reasonable number of hardware elements (that translates into system price). For the chosen number of directional modules a problem of synchronization (projected patterns overlapping is highly erroneous) was solved. We decided to apply spectral separation in a form of colored projection and color filters. This solution allows each detector to register only the pattern associated with it. A single frame pattern for structured light method was used to achieve presented measurement frequency. A set of algorithms was developed in order to perform all processing steps, including phase unwrapping, based only on a single image per detector. The final phase distribution is scaled into XYZ coordinates, therefore an extended common calibration process was introduced to receive a single multidirectional cloud as the output. The system is able to reconstruct dynamic objects in the form of point clouds, where each point, aside from XYZ coordinates, also contains an information about it’s normal vector. The future work will include improving the system accuracy and error-resistance.
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