Hi!

Do you think it is possible to write a macro which uses included
ies-data and creates an object of light-planes out of the data?

I think that povray light sources could represent an ies this
way, or do you think this would be impossible?

BTW, where to find information about writing macros? I know a bit
C / C++, and I used Povray some time ago, now I want to use it
again, but I need ies, so I would like to know if it will be
possible and where to get a good starting point.

Thank you, CU, Lars.

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In article <398### [at] gmxnet>, Lars <gro### [at] gmxnet> wrote:

> Do you think it is possible to write a macro which uses included
> ies-data and creates an object of light-planes out of the data?
> 
> I think that povray light sources could represent an ies this
> way, or do you think this would be impossible?

Uh, what is ies data? And what do you mean by "light-planes"?


> BTW, where to find information about writing macros? I know a bit
> C / C++, and I used Povray some time ago, now I want to use it
> again, but I need ies, so I would like to know if it will be
> possible and where to get a good starting point.

They are easy to learn...just read the documentation, and look at the 
macros which have been created. And if you have a specific problem, ask 
on these newsgroups.

BTW, this group is for discussion of programming, this post would have 
gone better in povray.advanced-users, povray.newusers, or povray.general.

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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Hi Chris!

Chris Huff wrote:

> Uh, what is ies data? And what do you mean by "light-planes"?

ies-files represent the light distribution of a source. This is
important if you want to simulate an architectural scene.

If there was a "parallel" area light in povray, one could write
the macro by modeling the light distribution with plane light
sources with different amplitudes.

I wonder if it makes sense to try something like this with a
sufficient amount of spotlights - though the "resolution" would
give bad performance.

I would like to try povray to simulate the behavior of some
materials in an interior scene, with the effects of different
light sources. At the moment this is impossible, as noone has a
real point light or spot light at home.

CU, Lars.

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In article <399### [at] gmxnet>, Lars <gro### [at] gmxnet> wrote:

> > Uh, what is ies data? And what do you mean by "light-planes"?
> 
> ies-files represent the light distribution of a source. This is
> important if you want to simulate an architectural scene.
> 
> If there was a "parallel" area light in povray, one could write
> the macro by modeling the light distribution with plane light
> sources with different amplitudes.

There are parallel lights in MegaPOV.


> I wonder if it makes sense to try something like this with a
> sufficient amount of spotlights - though the "resolution" would
> give bad performance.

The large amount of lights would probably make things render very slowly.


> I would like to try povray to simulate the behavior of some
> materials in an interior scene, with the effects of different
> light sources. At the moment this is impossible, as noone has a
> real point light or spot light at home.

You still haven't explained what format the ies data is in...is it some 
sort of image map specifying the color and intensity of a planar light 
source? Color and intensity over the surface of a patch or polygon? Or 
simply a bunch of light sources? Does it store the geometry of the 
scene, or just lighting?
It sounds like my pigmented light patch might be useful for this, I will 
have to get back to work on it...

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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Lars wrote:
> 
> Hi Chris!
> 
> Chris Huff wrote:
> 
> > Uh, what is ies data? And what do you mean by "light-planes"?
> 
> ies-files represent the light distribution of a source. This is
> important if you want to simulate an architectural scene.

I might have missed something. I remember having seen diagrams showing
the intensity of emitted light according to viewing angles. It was made
by a street lighting service in my company, and both depended on the
light source itself and the reflector. They used it in simulation tools
to study the resulting effet on actual buildings or bridges.

My suggestion would be (if the light source is small enough versus the
scene to avoid caustics issues) to use an extremely small transparent
sphere around your light source and to map a suitable filtering mask
around it.

-- 

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In article <3995D363.78C14227@club-internet.fr>, Francois Dispot 
<woz### [at] club-internetfr> wrote:

> I might have missed something. I remember having seen diagrams showing
> the intensity of emitted light according to viewing angles. It was made
> by a street lighting service in my company, and both depended on the
> light source itself and the reflector. They used it in simulation tools
> to study the resulting effet on actual buildings or bridges.

Something like the media scattering type diagrams in the POV manual?
Hmm, I wonder how difficult it would be to specify the falloff with a 
spline...

-- 
Christopher James Huff - Personal e-mail: chr### [at] maccom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Personal Web page: http://homepage.mac.com/chrishuff/
TAG Web page: http://tag.povray.org/

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