[Bf-cycles] GSoC - Spectral Rendering

David erwin94 at gmx.net
Wed Apr 10 01:20:54 CEST 2013

On Apr 10, 2013, at 12:55 AM, Brecht Van Lommel wrote:
> On Wed, Apr 10, 2013 at 12:08 AM, David <erwin94 at gmx.net> wrote:
>> this is by far the best visual explanation of what separates spectral
>> rendering from normal RGB rendering that I have seen:
>> http://www.luxrender.net/wiki/LuxRender_Textures_Spectrum#Gaussian_spectrum
>> All lamps in this image would be the same RGB color, and produce the
>> same result with non-spectral rendering.
> I don't think that's true? The exact result depends on the wavelength
> to RGB conversion function, but a wider gaussian distribution across
> the wavelength should give different RGB values than a narrow one? As
> the distribution gets wider there will a more even distribution across
> the RGB channels.
> It wouldn't be as accurate but the lights would still render different I think?
> Brecht.

Ah, you're right, and it is even sort of explained in the text I linked to, so I
feel especially dumb. ;)  The width of the distribution corresponds roughly to
saturation, it's basically just HSV.
So, the only effect that I can think of that is really not approximated by RGB
rendering is dispersion? I would love to see an image where the light spectrum
makes a noticeable difference, that isn't of a prism or a diamond...

till then, David.

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