CoucouHibou nous illumina en ce 2008-10-03 11:57 -->
> Warp <war### [at] tagpovrayorg> wrote:
>>   You can create a pattern from a df3 file, and consequently you can create
>> a pattern function from one. You can then call this pattern function with
>> spatial coordinates and it will return the value of the df3 at those
>> coordinates (interpolated).
> 
>   Hi again,
> 
>   I have a little question now. Concerning the interpolate mode in the
> density_file command: type 2 interpolation yields weird results! It creates
> some big cubic holes in my pattern function while interpolate 1 is correct. I
> thought the tricubic interpolation would be smoother and would not show this
> mesh-like effect that we can see on the trilinear interpolation, but it seems
> to have other defects that can not be compensated for.
> 
>   I do not know if this is normal as I do not know much about interpolation
> weaknesses (maybe it is just that I have a tricky function, I actually did not
> test this on spiral.df3). This is not crucial to my figure, as I compensate for
> the lack of smooth interpolation by a higher resolution in the df3, but I am
> just curious about it.
> 
>   Thanks for your answer,
> 
>   Hibou
> 
> 
> 

This is a known bug. When the interpolation encounter a zero, it algorythm 
generate some negative values resulting in those ugly artefacts.

A workaround is to have a DF3 file with NO ZERO values, but small values. Then, 
you use a color_map to turn those small values to a zero density.
I've tryed spiral.df3 and interpolate 2, and the result is orrible.

If you want to try the 3.7 beta, it should be corrected.

-- 
Alain
-------------------------------------------------
If Barbie is so popular, why do you have to buy her friends?

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