Iterative restoration algorithms for improving the range accuracy in imaging laser radar

Scannerless imaging laser radar has been a focus of research in these years for its fast imaging speed and high resolution. We introduced a three-dimensional imaging laser radar using intensified CCD as the receiver with constant gain and line modulated gain. The distance map of a scene is obtained from two intensity images. According to the transmission characteristics of the imaging system, a model of degeneration of the gray images is established and the range accuracy of imaging laser radar based on this model is analyzed. The results show that the range accuracy is related with the reflectivity, the actual distance and some other factors on the fast-distance-varying region, while it is mainly concerned with shot noise for the flat area. On the basis of the cause of measurement error and the distribution characteristics of noise, a method which uses iterative restoration algorithms on obtained intensity images is presented, Simulation is carried out and the results show that root mean square error of distance map obtained with this method is decreased by 50%, compared with the distance map obtained by measurement. Finally the restoration results of radar images are demonstrated to verify the effectiveness of this method.