Improvement of sensor accuracy in the case of a variable surface reflectance gradient for active laser range finders

In active laser range finders, the computation of the (x, y, z) coordinates of each point of a scene can be performed using the detected centroid p~ of the image spot on the sensor. When the reflectance of the scene under analysis is uniform, the intensity profile of the image spot is a Gaussian and its centroid is correctly detected assuming an accurate peak position detector. However, when a change of reflectance occurs on the scene, the intensity profile of the image spot is no longer Gaussian. This change introduces a deviation /spl Delta/p on the detected centroid p~, which will lead to erroneous (x, y, z) coordinates. This paper presents two heuristic models to improve the sensor accuracy in the case of a variable surface reflectance gradient. Simulation results are presented to show the quality of the correction and the resulting accuracy.