A Study of Precision Factors of Large-scale Object Surface Profile Laser Scanning Measurement

摘要

In this paper, we presented a method of using the laser scanning triangulation for the non-contact 3Drnsurface profile measurement of large-scale object. The characteristic of large-scale object non-contactrnmeasurement is analyzed and the measuring method is proposed. Main factors influencing measurement precisionrnsuch as image distortion and accurate designation of speckle center are analyzed and methods of solving thesernproblems are proposed. We designed a combined filter by which the pulse noise and the Gaussian noise of specklernimage can be eliminated efficiently. Using the characteristic of intensity distribution of laser speckle image wernproposed a new approximating method that could locate the center of laser speckle image at sub-pixel. Thernauxiliary variables are set to linearize the relationship between the image displacement and the distance, thernaccurate values of laser triangulation system parameters could be calibrated accurately and the measuringrnprecision is increased remarkably. Using the above techniques we designed a measuring system based on laserrnscanning triangulation. The results of the experiment show that these methods can raise the measuring precisionrnof large-scale 3D surface profile effectively.