## Gaussian Spectrum Tweet

Sub forum for help and tutorials.

Moderator: aoktar

### Gaussian Spectrum

Has anyone a good explaination what this node does? I just can't wrap my head around it. How and when is it supposed to be used?

Can anyone link me to a throughout explaination?

Thanks a lot.
DinoMuhic

Posts: 131
Joined: Wed Mar 25, 2015 10:24 pm

### Re: Gaussian Spectrum

Hi Dino,

Been looking into it myself, and I think in basic terms it's a way to give you colour based on realistic spectra.
Someone please correct me if I'm wrong here.

It's best described in images and a (very badly drawn) graph

So inputting those values (roughly) into the GS node (wavelength in μm not nm like the graph) and putting it in the Spec channel (Index = 1) gives you this:

Increasing the width value will widen the spectra included and eventually desaturate to white.
You can of course add variation to the wavelength to give you varying colours:

cheers
brasc
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brasco

Posts: 198
Joined: Wed Apr 13, 2011 2:56 pm

### Re: Gaussian Spectrum

Hi,
perfect explanation, brasco
In simple words we could consider it like another way to input colors. Since Octane converts the RGB colours to a spectrum, using this node, the color is not converted. It works in a similar way as the HSV space where the Hue is given by the Wavelength, the Saturation by the Width value (in the opposite direction, lower values will give more saturated colors), and finally the Value is given by the Power value. You can use it in any color input pin, for example in texture emission node gives much better results compared with a classic RGB node
ciao beppe

bepeg4d
Octane Guru

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Location: Italy

### Re: Gaussian Spectrum

Hi, can you elaborate on this

"for example in texture emission node gives much better results compared with a classic RGB node"

what do you mean by better results? accurate color? faster render?

Thanks

Sandi

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### Re: Gaussian Spectrum

bepeg4d
Octane Guru

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Location: Italy

### Re: Gaussian Spectrum

wow thanks beppe! using the gaussianspectrum for colored emission is wonderful solution. i will definitely remember it.

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Yambo

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### Re: Gaussian Spectrum

DinoMuhic

Posts: 131
Joined: Wed Mar 25, 2015 10:24 pm

### Re: Gaussian Spectrum

6850k|64gb|4 x GTX980ti
ratata

Posts: 73
Joined: Tue Aug 19, 2014 1:28 am
Location: Ljubljana, Slovenia

### Re: Gaussian Spectrum

Anyone know how to find the width and power of the wavelength on a given metal, like Copper on http://refractiveindex.info/?shelf=main&book=Cu&page=Rakic/ ?
MildMustard