Zeger Knaepen wrote:
> 
> > > Why is a fixed table necessary?
> >
> > Have you read what i wrote?
> Yep, and although I did misunderstand your question :) , my question
> remains: if it's possible to calculate 1600 fixed sample directions, it
> should also be possible (using the same or a similar algorythm) to calculate
> an arbitrary amount of fixed sample directions before the actual raytracing
> starts.  That way, you don't have to calculate the sample directions on the
> fly, and there wouldn't be an upperlimit of 1600 samples.  Or am I talking
> nonsense here?

No, but generating a good distribution is a slow and difficult thing.  So
calculating them before every render is no good idea.

Any practical solution will have to supply a precalculated table or a tool
for calculating it (so the user is more flexible with the maximum count).

> > I don't know a method to generate such a distribution in high quality that
> > would be fast enough to be run before every render - if you do feel free
> > to implement it.
> I don't know what a "cos theta density distribution" is, but aren't just
> random (and not (perfectly) uniform distributed) rays good enough?

"cos theta density distribution" means the density of the samples is not
constant but proportional to the cosine of the angle to the normal vector.

Whether random rays are 'good enough' is a matter of personal taste of
course but i don't think anyone would use a completely random sampling if
available.

> Oh, and an other question: reading the POV-Ray manual gave me the impression
> that the re-use of samples is based on the distance of the previous sample.
> As far as I can remember, there's nothing about the surface-normal in the
> manual.  But IMHO, the surface normal is more (or equaly) important to
> decide if samples could be re-used.  Am I wrong?  Or is this maybe already
> implemented?

I'm not sure what you mean but the distribution of the samples depends on
the scene geometry (or the surface normal if you want so).  There is a
switch in the POV source you can make the sample positions visible with so
you can see this.  If this is not what you mean please clarify what you
mean by 'basing the reuse of samples on something'.

Christoph

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Last updated 07 Dec. 2002 _____./\/^>_*_<^\/\.______

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