Hello,

I understand all well in the new implementation of the radiosity by
Nathan, but not this thing

max_sample 2         // CHANGE - this should be the same as the
brightest object
adc_bailout 0.01/2   // CHANGE - use adc_bailout = 0.01 /
brightest_ambient_object


what is the brightest object, where I find the number 2 in my scene?

Thanks,

Fabian.

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Fabian,

By "brightest object", I mean, "If you shoot rays into your scene, turn the
colors to grey-scale, what will be the biggest number, ignoring specular and
phong highlights?"

For example, if you have all "diffuse 1.0" objects with pigment colors no
greater than <1,1,1> and the sum of your light sources is 1.5, then the
brightest any object can look is 1.0*1.0*1.5 = 1.5.  On the other hand,
let's say one object is supposed to act like a light source, so you use
"ambient 20" with that object.  In that case, your brightest object will be
20 and you'd want to use a max_sample of 20 and a radiosity adc_bailout of
0.01/20.

-Nathan

Fabian Brau <fab### [at] umhacbe> wrote...
> Hello,
>
> I understand all well in the new implementation of the radiosity by
> Nathan, but not this thing
>
> max_sample 2         // CHANGE - this should be the same as the
> brightest object
> adc_bailout 0.01/2   // CHANGE - use adc_bailout = 0.01 /
> brightest_ambient_object
>
>
> what is the brightest object, where I find the number 2 in my scene?
>
> Thanks,
>
> Fabian.

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Couldn't this be calculated automatically? For example in the mosaic
previews?

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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You couldn't quarantee that the brightest object is hit during the preliminary
pass.

Margus

Nieminen Juha wrote:
> 
>   Couldn't this be calculated automatically? For example in the mosaic
> previews?
> 
> --
> main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Nathan,

Thank you very much for your answer.

Fabian.

Nathan Kopp wrote:
> 
> Fabian,
> 
> By "brightest object", I mean, "If you shoot rays into your scene, turn the
> colors to grey-scale, what will be the biggest number, ignoring specular and
> phong highlights?"
> 
> For example, if you have all "diffuse 1.0" objects with pigment colors no
> greater than <1,1,1> and the sum of your light sources is 1.5, then the
> brightest any object can look is 1.0*1.0*1.5 = 1.5.  On the other hand,
> let's say one object is supposed to act like a light source, so you use
> "ambient 20" with that object.  In that case, your brightest object will be
> 20 and you'd want to use a max_sample of 20 and a radiosity adc_bailout of
> 0.01/20.
> 
> -Nathan
> 
> Fabian Brau <fab### [at] umhacbe> wrote...
> > Hello,
> >
> > I understand all well in the new implementation of the radiosity by
> > Nathan, but not this thing
> >
> > max_sample 2         // CHANGE - this should be the same as the
> > brightest object
> > adc_bailout 0.01/2   // CHANGE - use adc_bailout = 0.01 /
> > brightest_ambient_object
> >
> >
> > what is the brightest object, where I find the number 2 in my scene?
> >
> > Thanks,
> >
> > Fabian.

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Margus Ramst <mar### [at] peakeduee> wrote:
: You couldn't quarantee that the brightest object is hit during the preliminary
: pass.

  Then the object is so small that it doesn't affect the scene anyways.
  And if there were any problem, you could always specify the correct value
by hand...

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Nieminen Juha wrote:
> 
> Margus Ramst <mar### [at] peakeduee> wrote:
> : You couldn't quarantee that the brightest object is hit during the preliminary
> : pass.
> 
>   Then the object is so small that it doesn't affect the scene anyways.
>   And if there were any problem, you could always specify the correct value
> by hand...
> 

Just an idea...

Not as obvious at it may seems, but the object may be out of the image.
If you're doing an animation with a traveling, 
the appearing/vanishing objects with radiosity may just impacts a lot
the brightness of the consecutive images.

Now, the question is "is using radiosity in an animation a reasonable thing ?".

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J. Grimbert <jgr### [at] atos-groupcom> wrote:
: Not as obvious at it may seems, but the object may be out of the image.

  It doesn't matter. It will be hit in the mosaic preview anyways (that's
what radiosity is about).

: Now, the question is "is using radiosity in an animation a reasonable thing ?".

  Why it shouldn't?

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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How much an object affects the scene depends on the balance of size and
brighness. Smaller objects just have to be brighter, proportionally to the area
of their projection, to give the same effect (not accounting for increased
statistical error due to limited sample rays)

Margus

Nieminen Juha wrote:
> 
>   Then the object is so small that it doesn't affect the scene anyways.
>   And if there were any problem, you could always specify the correct value
> by hand...
> 
> --
> main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Perhaps there could be a special keyword that you could apply to objects
which tells povray "this object is very small and very bright, so send more
radiosity rays here".

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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