High subdivision levels and memory issues

[cmann_2000]

I'm playing around with some high subdivision level terrains and bump maps on a single segmented, nurbed rectangle, and I am running into (shock!) memory issues. I'm sporting the 64 bit version with 8gb ram, and I'm easily using up the ram when I hit render. Here are my issues:

1) When I turn up the subdivision level too high, lightwave appears to freeze (I know it's not frozen, because if I leave it long enough, it'll recover). But during that time, I can't cancel the bloody process! Why not!?
2) When I try using limited region rendering, it takes the same amount of time, to within a couple seconds. The rate limiting step is building the polygons. So I can't break the render up into a few segments that way... And when I try shrinking the width of the camera to include only, say, 1/6th of the object that doesn't speed up the rendering more than a couple seconds; I still have to wait through the same amount of unresponsive render time.
3) Catmull-clark and subpatches will take the same amount of time for the same resolution (not the same subdivision number, of course). I naively expected one to be inherently better.
4) Subdividing the rectangle in modeler, then nurbin' it doesn't seem to help once I reach the same resolution.

So, is there a way to deal with a single, highly subdivided object at render time?

[Surrealist.]

APS is an option. But I would have to do more testing with it. So far, it has not helped me out of high polys situations.

I also run into this problem with any other thing that needs millions of polys. The solution I wind up using is to just figure out a way to deal with less polygons at a time. Simple as that.

When doing terrain-type stuff I add the texture as a bump map as well and then lover the subdivision level so I get some profile but let the bump map add detail.

[Infinite]

I had the same issue when using Catmull-Clark Subd surfaces, Lightwave would go nuts, eat up all memory resources on my 8 GIG machine and take forever too calm down. I think you just have to be careful what resolution you go upto in the viewport.

[cmann_2000]

Yeah, I agree that the only solution presently is to use fewer polys. I mean, the bump map pretty much adds the detail I need. I wouldn't be offended, though, if NewTek added something that could count the number of post-subdivision polys before you start rendering (that's pretty easy) and give a heads up if it's going to eat all the RAM. That, or otherwise figured out a clever way to not freeze the program while it's building the extra polys...

[Surrealist.]

Check out my tutorial in the beginning. I give the math for ccs and subD. If you are using just per object level you can simply calculate it. APS would be more difficult.