Surface digitization is an approach to obtain three-dimensional measurement of an unknown sculptured surface. The quality and the efficiency of surface digitization are two main concerns which have drawn much attention in the manufacturing industries. A cost-effective digitizing approach can not only reduce the measuring time, but also improve the accuracy of measurement. In the past, the digitizing methods were performed in such a way that the digitizing points were chosen at intervals with a constant distance. However, many local areas of a sculptured surface can be well-represented by fewer points. Therefore dense digitizing of conventional digitizing schemes is not efficient. In this paper, a new irregular digitizing scheme based on the wavelet transform is proposed. First an initial depth map of sculptured surface is obtained by using computer vision. From the initial depth map, the wavelet transform is used to select the necessary digitizing points for further digitization by highly accurate measuring equipment. Once the digitizing points are re-measured, the surface can be reconstructed by wavelet synthesis technique.

We present an adaptive compression and resampling technique using wavelet packet shrinkage. The motivating application is surface digitization for computer-aided manufacturing. The objective is to improve estimation accuracy using a sparse and irregular, but more accurate, resampling of the data. We provide modified thresholds for wavepacket shrinkage, heuristics for choosing the resampling grid, and a mean estimator using measured data. Computed results illustrate application of the proposed technique.

Surface digitization is a method for obtaining three-dimensional measurement of an unknown surface. The performance and quality of digitization are dependent upon the choice of digitizing devices and approaches. An efficient digitizing method not only reduces the elapsed time of the digitizing process, but also improves the precision of measurement. This paper presents a new nonuniform technique for digitizing of sculptured surfaces based on the short time Fourier transform (STFT). The digitizing distances in the x and y directions for each pre-divided block of the surface are adjusted according to the highest spatial frequencies contained in the block which is in contrast to the uniform technique in which the digitizing distance is determined according to the highest spatial frequencies of the entire surface. The speed of the digitizing process is thus improved and meanwhile the accuracy of the surface representation is maintained. Simulations and experimental results are provided to verify the proposed method.