It appears that the Illuminance RGB values saved by POV-Ray when it
dumps the radiosity data to a file, are only in the [0,1] range. However, if
you had a very bright light source aimed at a wall, surely the illuminance
at points on that wall should be well above 1. In turn, this wall will be
indirectly illuminating other objects and for realism we would really need
to allow values greater than 1, since the wall is now effectively a light
source. Is this not done because of artifacts? Comments?

Regards,
George Pantazopoulos

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George Pantazopoulos wrote:
> 
>     It appears that the Illuminance RGB values saved by POV-Ray when it
> dumps the radiosity data to a file, are only in the [0,1] range.

What makes you think this?

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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Looking at an entry of a rad data file, the first chunk contains the
bounce depth, the next three are the point (x,y,z), followed by the packed
surface normal vector. The next three numbers are the Illuminance R,G,B (I
got this info from ot_write_block() in octree.cpp). These numbers have
always been less than 1 in all the rad data I've ever looked at (and I've
ben poring through a lot lately). Also in ra_gather(), Illuminance is of
type COLOUR, which implies a [0,1] range.

George


"Christoph Hormann" <chr### [at] gmxde> wrote in message
news:3E1D7378.B0556557@gmx.de...
>
>
> George Pantazopoulos wrote:
> >
> >     It appears that the Illuminance RGB values saved by POV-Ray when it
> > dumps the radiosity data to a file, are only in the [0,1] range.
>
> What makes you think this?
>
> 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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George Pantazopoulos wrote:
> 
> [...]
> Also in ra_gather(), Illuminance is of
> type COLOUR, which implies a [0,1] range.

No.

Please also check 'max_sample' in the documentation (section 6.11.11.2.8)
which explains how you can indeed artificially limit the range of
illuminance values.

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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In article <3e1d8455$1@news.povray.org>,
 "George Pantazopoulos" <the### [at] attbicom*KILLSPAM*> wrote:

> Also in ra_gather(), Illuminance is of
> type COLOUR, which implies a [0,1] range.

Have you actually bothered to look at the definition for COLOUR?

-- 
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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Christoph and Christopher,
    You are right, COLOUR is made up of floats. I have yet to see a stored
illuminance value above 1 however. I'll try a more definitive test soon.
Thanks for your replies.

George


"Christopher James Huff" <cja### [at] earthlinknet> wrote in message
news:cja### [at] netplexaussieorg...
> In article <3e1d8455$1@news.povray.org>,
>  "George Pantazopoulos" <the### [at] attbicom*KILLSPAM*> wrote:
>
> > Also in ra_gather(), Illuminance is of
> > type COLOUR, which implies a [0,1] range.
>
> Have you actually bothered to look at the definition for COLOUR?
>
> --
> 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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I actually just managed to produce some Illuminance values above 1, using
the Cornell.pov scene. However, I had to up the amibient value of the light
patch from 0.78 to 100.0. The resulting render did not look good, and the
Illuminance values I got were still mostly in the [0,1] range, but there
with some in the 2-3 range, but nothing much higher. So it technically can
be done, but something still does not seem right. I'll have to do more
testing..

Thanks,
George

"George Pantazopoulos" <the### [at] attbicom*KILLSPAM*> wrote in message
news:3e1e1052$1@news.povray.org...
>
> Christoph and Christopher,
>     You are right, COLOUR is made up of floats. I have yet to see a stored
> illuminance value above 1 however. I'll try a more definitive test soon.
> Thanks for your replies.
>
> George
>
>
> "Christopher James Huff" <cja### [at] earthlinknet> wrote in message
> news:cja### [at] netplexaussieorg...
> > In article <3e1d8455$1@news.povray.org>,
> >  "George Pantazopoulos" <the### [at] attbicom*KILLSPAM*> wrote:
> >
> > > Also in ra_gather(), Illuminance is of
> > > type COLOUR, which implies a [0,1] range.
> >
> > Have you actually bothered to look at the definition for COLOUR?
> >
> > --
> > 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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