In article <3d8af25f@news.povray.org>,
 "Theo Gottwald *" <The### [at] t-onlinede> wrote:

> Did I hear some subtones saying that  the calculation diffrences on 
> mathematics/CPU's/OS'es may eventually influence the result in 
> (only/not only ?) radiosity so that the tiles would not fit perfectly 
> together IF they are not rendered on the same platform ?

The platform doesn't really matter...the tiles won't match up even if 
you render them on identical machines. A different portion of the scene 
is rendered for each tile, so the pseudo-random samples will be 
different, giving slightly different shading for each tile. It is likely 
that the only way to avoid artifacts is to ensure that enough data is 
computed before the render starts...but then, I don't know how POV 
handles adding additional data during rendering in the current 
single-threaded version. Radiosity is the only thing that causes this 
problem, but there are other things that could cause similar problems in 
the future...some kind of optimized reflection blur, for example. Maybe 
photons with jitter would also be a problem.

You could overlap the tile edges and interpolate to smooth out the 
transitions, "over-rendering" the image. This would probably make the 
artifacts invisible in most cases without processing to find them, but 
is less efficient. However, it could be done with the current version + 
some clever scripts and a program to merge the tiles together.


> I'd prefer if there would be something "builtin" in the next 
> POV-version that would enable to make "tiling" possible and maybe 
> some support from the normal POV-Shell ?
> In the easiest form that would be the possibility to start two processes,
> telling each which part of the pic to render. (= simple SMP Support).

If it was that easy, don't you think it would have been done already?

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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