Alain <aze### [at] qwertyorg> wrote:

> > "Edouard"<pov### [at] edouardinfo>  wrote:
> >>> Is this one better?
> >>
> >> The wax looks just right, you can see the sizes just at a glance by the SSLT!
> >>
> >> Cheers,
> >> Edouard.
> >
> > In this experiment, I intended to make the size of the flame proportional to the
> > size of the candle. So, I adjusted the lights powers according to the sizes
> > proportionally, ie: *2 for the biggest, *1, *1/2, *1/4 respectively. I don't
> > know the law for the illumination of flames wrt their size. I suppose the
> > illumination comes from the surface of the flame, and therefore follows a
> > quadratic law. My powers are surely wrong for flame powers proportional to the
> > flame sizes.
> >
> > However, in RL, the size of the flame is generally not proportional to the size
> > of the candle ...
> >
> > I also set the fade_distance in the same order of magnitude than the area light
> > (twice). I am a bit confused by the fact that the dome is so barely visible,
> > despite 4 candles. But, after all, they are small (the biggest is 16 cm high)
> > and the dome is 5 metre from there. Maybe relative illuminations are correct.
> >
>
> In a flame, the light comes from the whole volume, and the flame is
> essentialy transparent.
>
> Make this test: light a candle and light some other light, place them to
> project the shadow on a wall or similar surface. Now, take a look of the
> shadow of the candle and it's flame. It's only effect on the light
> passing through it is from it's lower than air ior.
>
> Even the flame of a camp fire is essentialy transparent. You see it only
> because the gaz of the flame is incandescent and emit light.
> Same thing with the flame from a gaz stove.
> Model those flames using emissive media, without absorbtion nor
> scattering media.
>
>
>
>
> Alain

Thanks for advise.

Do you have such a model you can share?

I think however that the incandescent particles in the flame scatter the light
of the others, and that they are also somewhat opaque and have an absorbing
behaviour. Other particles or atoms might also scatter their light. It seems
that a flame is quite a complex object.

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