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Error Model of a Coded-Light Range Sensor

M. Trobina
164, 1995
Communication Technology Lab, Image Science Group, ETH


This paper describes the measurement principle, the mathematical model, the calibration procedure, and the error model of a range sensor based on the Coded-Light Approach. The sensor consists of a CCD camera and a stripe projector. 3-D measurements are realized by the intersection of camera rays with the planes generated by the stripe projection. Using projective geometry renders camera and projector model linear. A calibration procedure based on general least squares estimation is proposed. The estimation model consists of the analytic and stochastic model of the range sensor, which yields estimations of the model parameters as well as their accuracies. With introduction of unknown 3-D check points in the estimation model, the accuracy of the range measurements is obtained as the main result of this work. The confidence interval of the range measurements is represented as an error ellipsoid. It turned out that the longest axis of the error ellipsoid is almost parallel to the projector's optical axis. The noise dependence on distance to the camera, and on orientation of the measured surface, is given. The empirical accuracy achieved in our experiments confirms the estimated theoretical precision as well as the orientation and the axes lengths of the error ellipsoid.

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  author = {M. Trobina},
  title = {Error Model of a Coded-Light Range Sensor},
  year = {1995},
  month = {September},
  number = {164},
  institution = {Communication Technology Lab, Image Science Group, ETH},
  keywords = {robot vision, calibration, measurement, range data}