Thank you. This could be an idea. IES format gives luminosity in function of
horizontal and vertical angle.
This morning I developed a software that reads an IES file and write a file
with a set of spot light, one for each angle. It works but if the angle
discretization is fine, the number of spotlights created i beg and the
rendering gets slow.
I will test your idea, to see if it gives better performances.
The procedure is not known to me at the moment but I can try to manage.
Please if you can send me any information about the procedure or just an
example, it would be helpfull.

Many thanks.

Gianluca

"Peter Popov" <pet### [at] vipbg> ha scritto nel messaggio
news:tdlg10d9nvsagu8ulngjobph39raj9vfhv@4ax.com...
> On Wed, 28 Jan 2004 12:13:39 +0100, "Gianluca Massaccesi"
> <gia### [at] tinit> wrote:
>
> >There is a way of introducing angle-dependent light source?
> >For example considering as input a file in IES format for light sources?
>
> I don't know how exactly the data is represented in the IES format but
> I guess it's a projection of a spherical surface on a rectangular area
> which holds luminosity and/or spectral values. If it can be converted
> to PNG with alpha (if necessary), you can use it as an image_map
> (map_type 1) on a tiny sphere which you then put around the
> light_source and give it no_image. Do not use looks_like because it
> implies a no_shadow flag on the sphere and you do want it to cast a
> shadow (a filtered luminosity map, sort of). You know, with some luck
> I might not even be talking complete gibberish :)
>
>
> Peter Popov ICQ : 15002700
> Personal e-mail : pet### [at] vipbg
> TAG      e-mail : pet### [at] tagpovrayorg

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