virtualmeet wrote:
> To explain better, suppose we have a grid of 4x4x4 points.

If you pre-calculate samples in a gird, you create a voxel array, aka
density map in POV-Ray. This is not the same as an isosurface, and even
though sampling a voxel array is fast, it is also extremely inaccurate
unless you assume you have infinite memory. Even worse, once your voxel
array approaches a certain size, you need to calculate a lot more samples
than samples hat are visible. Hence, your voxel array calculations *and*
memory requirements grow O(n1^3) regardless of image resolution (where n1 is
the grid size in one dimension), while isosurface memory requirements are
somewhere around O(log n2) and computation requirements are O(n3*log n2)
where n3 is the number of pixels occupied and n2 is a measure of function
complexity (aka recursive steps of the approximation algorithm).

	Thorsten

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