Abstract: Precise measurement and reconstruction of a free-form surface are the important factors to affect the reproduction accuracy for parts with free surfaces. In the traditional reverse, the two processes are independent, and unable to be evaluated effectively. In order to improve the speed and precision for surface measurement and reconstruction, a new method is proposed based on coordinate measuring machine (CMM) adaptive measurement method to reconstruct surfaces. In the measurement, points got from the sample are fitted to calculate the next point and its measurement vector, and guide the CMM measure the automatically. After fitting the free surface model of the measured cloud, the error between points on fitting model and sample is detected and calculated. If the error is big, the actual detected points are added to reconstruct the model again. The accurate data and the elaborate surface model are obtained by detecting and updating the fitted model until the accuracy meets requirement. Furthermore, a computer graphics display method is used to make the calculation examples process visual to verify the proposed method. The empirical results show that the accuracy of measurement and reconstruction reaches the μm level, and the reverse cycle for free form surface is multiply shortening down, and the algorithm robustness is high.

Key words: free-form surface;adaptive measurement;surface reconstruction;precision evaluation