This work was supported in part by grants from the National Science Foundation (ASC 93-18180) to Mark Ellisman, Donald Greenberg, and Sid Karin, from the National Institutes of Health National Center for Research Resources (RR 04050) to Mark Ellisman, and by the NSF/ARPA Science and Technology Center for Computer Graphics and Scientific Visualization (ASC 89-20219). We gratefully acknowledge equipment grants from Hewlett-Packard, on whose workstations this research was conducted. Turbine blade dataset courtesy of GE Corporate Research and Development.