"Jaime Vives Piqueres" <jai### [at] ignoranciaorg> wrote in message
news:200### [at] ignoranciaorg...

>   No, I mean to not involve here the Lumens value.



Okay. But if I read the formula right, it is still implicitly present, as
lct/REF_WHITE is no more normalized. It should be more or less equivalent.



BTW I have some colour theory ideas for lightsys, but I need to test them
first. If I believe them to be of any interest, I'll mail them to you.





> The overall scene
> luminosity can still be controlled with EXPOSURE, and the sun/sky
> intensity (lumens) with Intensity_Mult. That is, I can setup Skylight
> ith Intensity_Mult to have an intensity proportionally correct respect
> to the other lightsys lights, changing the overall luminosity of both
> at once with EXPOSURE.
>
>  If you come up with a way to convert Y to Lumens, that would be
> aditionally nice, because sun/sky intensity will be automatically
> proportional to the lightsys lights (if you feed them with realistic
> lumens values, of course).



That was my goal from the start ;-)





> > It's not that complicated, really. It looks like it is, but it really
> > is mathematical formulas copied from the paper into SDL.
>
>   That is exactly what I was refering to: these papers are usually for
> people who understand maths.



I just ignored the parts I did not understand ;-)



<snip>

>  Hmmm... I suppose you're saying that you don't want ths sky being
> lighted with radiosity? Yes, that seems logical, as it changes the
> exact colors calculated by Skylight, and the model is then not accurate.



Yes and no. I do not want the sky to be lighted by anything but itself.
Moreover, I want the sky to act as a light_source for radiosity, hence the
high ambient value and higher then <1,1,1> colours as you go near the sun.





>  But, on the other hand, the POV docs encourage to use global ambient
> set to 0 for radiosity with light sources, wich is what I do usually, to
> use predefined and existant textures wich have ambient (rather than
> changing all the textures to set ambient to 0).



Yes, POV says to use ambient 0 in radiosity for non-light-emitting objects.
But I want the sky to be luminous, that is to light objects in the scene. It
is no only a pretty / accurate (?) background, it also provides a realistic
(? again) outdoor light setup.





> What's the solution in
> that case? I can't think of anything right now...



What are the problems with the way it originally is? Tell me what isn't to
your taste, I'll try to solve it.





> > I bet it is diffuse 1, which makes the sky colors dependant on the
> > lighting, so the difference in orientation of the polygons shows.
>
>   You're right! And don't worry: "brilliance 0" solves partially the
> problem.:) Still, it's not the correct method to use your include,
> because the sky gets excesively bright. I suppose it can be solved
> decreasing the overall luminosity and decreasing the weight of the
> sun... will try this too.



Decreasing the weight of the sun will probably increase the sky luminosity.




>   Next time I will post a first WIP for the scene where I'm using
> Skylight.inc... regards.





I am awaiting your image impatiently.



I hope you will not have to struggle too much with my file ;-)





Povingly,





Philippe

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