SAMPLING UNCERTAINTY IN COORDINATE MEASUREMENT DATA-ANALYSIS

There are a number of important software related issues in coordinate metrology. After measurement data are collected in the form of positio n vectors, the data analysis software must derive the necessary geomet ric information from the point set, and uncertainty plays an important role in the analysis. When extreme fit approaches (L-infinity norm es timation approaches) are employed for form error evaluation, the uncer tainty is closely related to the sampling process used to gather the d ata. The measurement points are a subset of the true surface, and, con sequently, the extreme fit result differs from the true value. In this paper, we investigate the functional relationship between the uncerta inty in an extreme fit and the number of points measured. Two major is sues are addressed in this paper. The first addresses and identifies t he parameters that affect the functional relationship. The second deve lops a methodology to apply this relationship to the sampling of measu rement points. (C) 1998 Elsevier Science Inc.