Ken W. Brodlie Muhammed Rafiq Asim Keith Unsworth Constrained Visualization Using the Shepard Interpolation Family. 809-820 2005 24 Comput. Graph. Forum 4 http://www.eg.org/EG/CGF/volume24/issue4/v24i4pp809-820.pdf db/journals/cgf/cgf24.html#BrodlieAU05