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Gaussian Spectrum

PostPosted: Fri Jan 29, 2016 1:05 pm
by DinoMuhic
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.

Re: Gaussian Spectrum

PostPosted: Fri Jan 29, 2016 2:53 pm
by brasco
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 :)

Image


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:

Image

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:

Image


cheers
brasc

Re: Gaussian Spectrum

PostPosted: Fri Jan 29, 2016 4:35 pm
by bepeg4d
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

Re: Gaussian Spectrum

PostPosted: Fri Jan 29, 2016 6:31 pm
by ratata
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

Re: Gaussian Spectrum

PostPosted: Sat Jan 30, 2016 7:40 am
by bepeg4d

Re: Gaussian Spectrum

PostPosted: Sat Jan 30, 2016 8:37 am
by Yambo


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

:)

Re: Gaussian Spectrum

PostPosted: Sat Jan 30, 2016 6:43 pm
by DinoMuhic

Re: Gaussian Spectrum

PostPosted: Sat Jan 30, 2016 8:01 pm
by ratata
Thanks for the links!

Re: Gaussian Spectrum

PostPosted: Mon Nov 07, 2016 9:38 am
by MildMustard
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/ ?