On 10/26/2013 08:10 PM, Alain wrote:
>
> I have'nt tryed the third version, but I got very good renders, much
> faster after some little changes to your code.
>
> First, max_gradient 160 if huge overkill.
> Using max_gradient 1.5 resulted in a nice render without any message
> about max_gradient been to small or to large.
> Next, I used:
> #declare MinFact = 0.6;
> evaluate 1.5*MinFact, sqrt(1/MinFact), 0.7
> and got a slightly faster render.
>
> Next, I reduced the contained_by object as follow:
> box {<-0.34,0.02,-0.34><0.34,0.908,0.34> }
>
> It's now much tighter and large enough to contain the whole isosurface.
> This got me another performance increase.
>
> Alain

Yes, good suggestions. I didn't tighten up my scribble and render set up 
before posting and I've never gotten my head to understand the evaluate 
option of isosurfaces.

Your post reminded me of one note I forgot to mention. On reading the 
image file, it is possible to play with the gamma option - even outside 
the range of common gamma values. You can get interesting scalloping 
effects. Especially true where the image is used for flat surface 
displacements.

Bill P.

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