I haven't investigated it. If 65000 samples doesn't help, we can always try
to go to 2^32 samples  :-)

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Apache wrote:
> Maybe you're right. I don't know. But I know that x*x is faster than
> src_vec->x*src_vec->x.

A reasonably smart compiler will optimize "src_vec->x * src_vec->x" to "x =
src_vec->x; x * x", but I doubt it would change "pow(x, 2)" to "x * x".

> Haven't thought about it really. I have this blurry
> and faint feeling that the power function is incorporated in most cpus. If
> not, please tell me.

Even if pow is included on the CPU, multiplication is much faster (AFAIK).

Anders

--
#macro E(D)(#if(D<2)D#else#declare I=I+1;mod(pow(.5mod(I 6))*asc(substr(
"X0(1X([\\&Q@TV'YDGU`3F(-V[6Y4aL4XFUTD#N#F8\\A+F1BFO4`#bJN61EM8PFSbFA?C"
I/6 1))2)<1#end)#end#macro R(D,I,T,X,Y)#if(E(D))R(D-1I,T,Y/2X)R(D-1I,T+Y
/2Y/2X)#else box{T T+X+Y pigment{rgb E(2)*9}}#end#end R(10,5z*3-1v*2u*2)

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In article <3e1c5b48@news.povray.org>,
 "Apache" <apa### [at] yahoocom> wrote:

> I haven't investigated it. If 65000 samples doesn't help, we can always try
> to go to 2^32 samples  :-)

Hmm...4GB per byte of sample. Stored as 3 floats, at 4 bytes each for 12 
bytes a sample, that would be 48GB. If 5 bytes are sufficient, only 20GB.
And I wonder what the render times would be with 4,294,967,296 
samples...the results would be really nice though. Little need for 
photons, with some adjustments most other things could also be done with 
this algorithm.

-- 
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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Gilles Tran wrote:
> 
> Just a general comment about this "search for more radiosity" samples, which
> I sincerely hope will be fruitful and lead to better, faster radiosity.
> In my experience, "more samples" doesn't mean "better radiosity". In fact,
> this is true between, say, 0 and 500, but after that, having more samples
> just doesn't address the artefact issues : ...

This is one of the reasons why i have been focussing on finding a better
solution for lower sample counts.  With higher ray counts the differences
between distributions will diminish as long as they maintain the correct
density falloff.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 31 Dec. 2002 _____./\/^>_*_<^\/\.______

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"Anders K." <and### [at] kaseorgcom> wrote:
> A reasonably smart compiler will optimize "src_vec->x * src_vec->x" to "x
=
> src_vec->x; x * x", but I doubt it would change "pow(x, 2)" to "x * x".
>
> Even if pow is included on the CPU, multiplication is much faster (AFAIK).

Right.

As to the direct support of pow() in the CPU, this is very and very
unlikely... Usually, pow() is implemented as a function that computes its
result using the

x ^ y == 2 ^ (y * log2(x))

formula, with *some* support for the log2(x) in the CPU (power of 2, being a
shift, is quite efficient, of course). log2(x) may easily take a hundred or
so cycles, plus those extra calculations, plus the overhead of the function
call... so, hope you got the idea.

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It's just a matter of rewriting the whole POV-Ray package and especially the
octree code so that the calculations and data can be divided over a few
thousand computers with the internet as communication medium. Maybe someone
is willing to hardcode everything into a pure POV-Ray chip? rant rant
rant.............. :-)

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What what would be the best (set of) scene(s) to test sets for lower sample
counts.

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You folks absolutely convinced me!

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I have this set ready for testing. It contains of 3200 samples. I'm
currently running some test scenes while another process is calculating a
set of 32000 samples at low priority (cygwin's nice). I have compiled a
patch of POV-Ray with those 3200 samples. The complete windows source files
(including windows executable) are available for download at
http://24.132.254.158/experiments/elipovray350winvc7src_3200samples.zip (143
kb). For those who only want to download the changed files (for all
platforms):
http://24.132.254.158/experiments/elipovray350_patched_3200samples.zip
(5,721 kb) My upstream here is 15kb/s max, so be patient if it's slow...

Please do some test, I have limited CPU power nowadays...ehhhh... as ever
:-P

Regards,
Apache

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I was unable to download the first file, and the second file is source only.

--
Anthony Bennett

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