Low latency real time 3D sensor utilizing optimized aperiodic fringe patterns

Pattern projection-based stereo 3D sensors are widely used for contactless, non-destructive optical 3D shape measurements. In previous works, we have shown 3D measurement systems based on stereo matching between two cameras with GOBO-projected aperiodic fringe patterns. We have also demonstrated a low latency 3D reconstruction algorithm (BICOS), which can be used for real time 3D measurements. We showed an optimization method for the projected aperiodic fringe patterns with the purpose of making the measurements more robust and to reduce the pattern sequence length without sacrificing 3D model completeness. In this contribution, we demonstrate a sensor for a medical application which aggregates these developments. Our sensor is used to monitor patient movement during radiation therapy. In this application a low measurement latency is of high importance. A significant part of this latency is caused by image acquisition. We show that we can reduce the number of required image pairs to 6 when optimizing the projected aperiodic fringe patterns. In combination with our BICOS algorithm, we can achieve total measurement latencies of below 80 ms at an accuracy of 355 µm in a measurement field of 1 m × 2 m.