John, It is hard to quantize. With very small number of planes along one axis, you should expect to see something weird. Please send me a JPEG or GIF showing your problem, so I know exactly what it is. Test62 is blank until you slide the slider, but its not relevant to what you want to do. Bill p.s., please remember to send the JPEG or GIF On Fri, 14 Feb 2003, John Osborne wrote: > Do you have a sense of how far out-of-square you have to go to see the > problem? I am also giving folks the ability to do interactive > iso-surfaces but haven't been able to make it work yet--I just get a > blank display. I'm using the Tutorial code as a starting point. Test62 > doesn't seem to do anything either but the code also doesn't seem > complete either (from my first read of it). You're probably right to be > less concerned about aliasing with this type of visualization but the > memory issues can still be problematic with bigger grids.