"Chris R" <car### [at] comcastnet> wrote:
> Cousin Ricky <ric### [at] yahoocom> wrote:
> > On 2022-03-21 14:41 (-4), Cousin Ricky wrote:
> > > On 2022-03-21 10:58 (-4), Chris R wrote:
> > >> I am working on a scene that is lit by moonlight coming through a window with
> > >> partially open blinds.  I use LightSys, and have set up the light source as an
> > >> area light just outside of the window itself.
> > >>
> > >> I was wondering if anyone had suggestions for good color/lumens combinations to
> > >> simulate moonlight.  I am currently using a made-up color of <0.45, 0.5, 0.75>
> > >> and an intensity of 1.0 with no fading, (so I guess I'm not really using
> > >> LightSys to great effect here).  Has anyone done any spectrum analysis for
> > >> moonlight to suggest better values?
> > >
> > > Lumens is not what you want for moonlight; this is a measure of the
> > > total amount of light emitted (or reflected, in this case).  Lux is the
> > > proper unit for a light source that is effectively at infinity.
> > >
> > > Wikipedia says 0.05 to 0.3 lux.  That's quite a range!
> > >
> > > To get a narrower precision, a preliminary calculation is:
> > > [snip]
> >
> > I just noticed that nowhere in your OP did you mention that the Moon is
> > full.  Please keep in mind that my reply, as well as the Wikipedia
> > figures, are for a full Moon.
>
> Yes, I am using a full moon for this scene.  I have added a visible element for
> the moon, but none of the views I have been working on for the scene actually
> make it visible, so the texture of the moon object itself is not as important.
> I am mostly looking to get the right color/intensity for the light source.
>
> I am pretty sure LightSys does not have anything that converts lux to
> light_source color, so I'll have to look into that.
>
>
>
> -- Chris R.
I spent a few minutes of internet research and found that lux to lumens
calculations are pretty simple, so I updated my moon light-source generating
macro to do that conversion, and am using your lux values to try things out from
there.  I am using the size of the area_light in converting from lux to lumens,
and am getting reasonable values, using a very cool whitepoint, so I'm happy
with it.

Thanks for the information!


-- Chris R.

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