Fusion of Time-of-Flight Depth and Stereo for High Accuracy Depth Maps Reporter ：鄒嘉恆 Date ： 2009/11/17

Introduction They provide real time depth estimates by combine stereo and Time-of-flight.

Outline Motivation Multi-sensor calibration  Geometric calibration  Photometric calibration  Calibration verification Sensor fusion Experimental results Conclusion

Motivation Problem:  Laser scanner are too slow for real time use.  Stereo fails on textureless scenes.  TOF is low resolution, noisy, and poorly calibrated.

Multi-sensor setup SR3000:  176x144  Operational range up to 7 meters 2 CCD stereo cameras limit the calibration range from 1m to 1.4m

Multi-sensor calibration Geometric calibration

Multi-sensor calibration Photometric calibration

Multi-sensor calibration Calibration verification-plane experiment

Multi-sensor calibration Calibration verification-plane experiment

Multi-sensor calibration Calibration verification-plane experiment Calibration verification-box experiment

Sensor fusion f d : the local evidence for node i f s : a symmetric function measures the smoothness assumption about the scene f r : the additional local evidence based on the measurement from the TOF sensor.

Experimental results Using TOF  (A)local method  (B)local method with LUT  (C)global method  (D)global method with LUT Using stereo  (E)local method  (F)global method (G)local fusion method (H)global fusion method

Experimental results

Conclusion They present a simple and effective calibration method to improve the performance of time-of-flight sensors. Their method can achieve an absolute accuracy of about 5mm over a range of one meter. The fusion results reduce the over-all error by 50%.