This research was performed under the auspices of the U.S. Department of Energy, contract No. W-7405-ENG-48 and LDRD grant No. 96-ERI-003, with the support of H. Martz and K. Hollerbach. J. Pearlman, M. Abramowitz, E. Nicolas, J.P. Hebert, M. Cody and D. Garrett helped improve VISU by providing invaluable bug reports and suggestions.