Leo wrote:
> [...]
> 
> Yes, it is the discontinuous nature of the DIV function itself that causes
> the problem.  Computing just one 'column' gives a MAX_GRADIENT of 77.
> Still quite high, but better than the 59000 reported for the whole.
> 
> My concern, really, as that the artifact is showing up in the continuous
> section.  I am going to rerender with the MAX_GRADIENT set to 77 and see if
> this fixes it.

To clear up two misconceptions here: the maximum gradient reported by 
POV is not necessarily the real maximum gradient occuring (which would 
be infinite in cases of discontinuities anyway).  And too low 
max_gradient settings can lead to artefacts in areas with lower 
gradients (which should be perfectly clear, otherwise only the grandient 
at the surface would be relevant).

And it is not that the use of a discontinuous function anywhere in the 
isosurface automatically leads to an infinite gradient, you just have to 
know what you are doing.

Christoph

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