Do you think is possible to implement a new function for a light source,
with rays function of solid angle (seeIES standard). I different words,
having the possibility of controlling the energy of rays in relation with
horizontal and vertical angle. It would be very usefull for modelling
ambient lights, from producers measurenìment files, and for other purpose.

Thank you all.

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> Do you think is possible to implement a new function for a light source,
> with rays function of solid angle (seeIES standard). I different words,
> having the possibility of controlling the energy of rays in relation with
> horizontal and vertical angle. It would be very usefull for modelling
> ambient lights, from producers measurenìment files, and for other purpose.

This could probably be done in SDL with a sphere with a filtering pigment
around a normal light source, unless I misunderstand.

 - Slime
 [ http://www.slimeland.com/ ]

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Gianluca Massaccesi wrote:
> Do you think is possible to implement a new function for a light source,
> with rays function of solid angle (seeIES standard). I different words,
> having the possibility of controlling the energy of rays in relation with
> horizontal and vertical angle. It would be very usefull for modelling
> ambient lights, from producers measurenìment files, and for other purpose.

If you are working with isosurfaces (and if you don't care about
shadows), then you can calculate how much a light source illuminates
a point on the surface by using functions in SDL. (I.e. you don't
need to patch POV-Ray to do this.)

I once used such a technique to make a few simple images.
Some of them can be found in this thread:

http://news.povray.org/povray.binaries.images/thread/%3CXns93A4378303A9Ftorolavkhotmailcom%40204.213.191.226%3E/
or http://tinyurl.com/ytkvh

It should also be possible to do something similar with meshes
made up of (small) triangles.


Tor Olav

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Tor Olav Kristensen wrote:
> Gianluca Massaccesi wrote:
> 
>> Do you think is possible to implement a new function for a light source,
>> with rays function of solid angle (seeIES standard). I different words,
>> having the possibility of controlling the energy of rays in relation with
>> horizontal and vertical angle. It would be very usefull for modelling
>> ambient lights, from producers measurenìment files, and for other 
>> purpose.
> 
> 
> If you are working with isosurfaces (and if you don't care about
> shadows), then you can calculate how much a light source illuminates
> a point on the surface by using functions in SDL. (I.e. you don't
> need to patch POV-Ray to do this.)
 >
 > I once used such a technique to make a few simple images.
...

I forgot to mention that you would have to make a function that
describes the energy distribution at different angles around (or
relative to ?) the light source.

The source code for the mentioned images can be found here.

http://news.povray.org/povray.text.scene-files/thread/%3CXns93A54E262AE2torolavkhotmailcom%40204.213.191.226%3E/
or http://tinyurl.com/2dbua

(It might give you some hints about how to start attacking this
problem.)


Tor Olav

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in news:4044ef3b$1@news.povray.org Slime wrote:

> This could probably be done in SDL with a sphere with a filtering
> pigment around a normal light source, unless I misunderstand.
> 

The hard part would probably be to convert luminance file to functions. 
Ian Ashdown made a parser available for parsing IESNA LM-63 and similar 
files, maybe that could be a start.

Also if I remember well, there was somebody who patched povray in a way 
that it could work these IES files, but the code was never published. 
Can't find the discussion, it was about a year (or more) ago.

I would realy welcom a POV-Ray feature that could read and deal with such 
files directly. Many manufacturers of lighting systems make these data 
available.


Ingo

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