2D Wavelet Transform Data Compression with Error Level Guarantee for Z-Map Models

Abstract

Computer simulations are generally used to find any potential problems prior to the actual manufacturing process of workpieces. Most of the workpiece shape is in a Z-map representation, which requires a large amount of data to accurately record a high resolution model. To solve this problem, we propose an irreversible compression algorithm for Z-map models using two-dimensional wavelet transform with a specified maximum error. The input shape data is transformed by using 2D wavelet, and the maximum errors caused by virtual pruning of highfrequency components are recorded simultaneously. Nodes in the wavelet tree are pruned if the absolute value of its error by the virtual truncation is within a tolerance value specified by the user, and the remaining tree nodes are compressed reversibly using gzip compression library.