My First Spectral rendering back

(L) [2017/06/09] [ost by jbikker] [My First Spectral rendering] Wayback!

Been playing with spectral rendering:

[IMG #1 spectraldragon.jpg]


Completely new world for me so be gentle. [SMILEY :)]
This is with tracing four wavelengths at once; three of them are killed when a wavelength dependent pure specular dielectric is encountered.

The tracer accumulates CIE XYZ colors and converts them to RGB using the approach proposed by Brian Smits ([LINK http://www.cs.utah.edu/~bes/papers/color/paper.pdf]). I chose not to use the more accurate method of Meng et al., ([LINK https://jo.dreggn.org/home/2015_spectrum.pdf]) as it requires substantially more involved calculations.

EDIT: another one:

[IMG #2 dragon_spectral.jpg]


This is unidirectional path tracing so the caustics took a while to converge, and they are still noisy...

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[IMG #1]:Not scraped: /web/20190530213322im_/http://ompf2.com/download/file.php?id=259&sid=8796f25e195359104485cc977d9bd550
[IMG #2]:Not scraped: /web/20190530213322im_/http://ompf2.com/download/file.php?id=260&sid=8796f25e195359104485cc977d9bd550

(L) [2017/06/09] [tby jbikker] [My First Spectral rendering] Wayback!

Been playing with spectral rendering:
spectraldragon.jpg
Completely new world for me so be gentle. [SMILEY :)]
This is with tracing four wavelengths at once; three of them are killed when a wavelength dependent pure specular dielectric is encountered.
The tracer accumulates CIE XYZ colors and converts them to RGB using the approach proposed by Brian Smits ([LINK http://www.cs.utah.edu/~bes/papers/color/paper.pdf]). I chose not to use the more accurate method of Meng et al., ([LINK https://jo.dreggn.org/home/2015_spectrum.pdf]) as it requires substantially more involved calculations.
EDIT: another one:
dragon_spectral.jpg
This is unidirectional path tracing so the caustics took a while to converge, and they are still noisy...

(L) [2017/06/15] [ost by shocker_0x15] [My First Spectral rendering] Wayback!

Cool [SMILEY ;)]

What is the material?
Do you implement Hero wavelength spectral sampling?

(L) [2017/06/15] [ost by jbikker] [My First Spectral rendering] Wayback!

Quartz. I'm tracing four wavelengths as proposed by the Hero paper, but I have not implemented their MIS scheme yet. In this case it's useless by the way; the quartz will reduce weights for all wavelengths but the hero to zero anyway. For the floor and walls the four wavelengths are very effective, obviously.

(L) [2017/06/15] [ost by ziu] [My First Spectral rendering] Wayback!

Since we're talking secondaries here, did you guys notice this article?
"Building an Orthonormal Basis, Revisited"; Tom Duff, James Burgess, Per Christensen, Christophe Hery, Andrew Kensler,
Max Liani, and Ryusuke Villemin:
[LINK http://jcgt.org/published/0006/01/01/paper.pdf]

It describes a fast and accurate way to generate an orthonormal basis for things like random sampling. I got the link from a Twitter post by Carmack some time ago but I don't remember seeing it linked here yet.

I watched the Hero presentation at EGSR a couple years back. The results looked really excellent.

(L) [2017/06/15] [ost by jbikker] [My First Spectral rendering] Wayback!

I hadn't seen it, but it looks good.
On a related note: [LINK https://www.shadertoy.com/view/lssfD7] , Lambert reflection without tangents.

(L) [2017/06/15] [ost by friedlinguini] [My First Spectral rendering] Wayback!

Whoah, weird. I had thought you could do something very similar, but by adding a random point on the *interior* of a sphere to the normal, rather than on the surface: [LINK http://psgraphics.blogspot.com/2014/09/random-diffuse-rays.html]. Obviously it would be better to use exactly two random parameters than an unbounded number of them, but I have a hard time wrapping my brain around the possibility that both are correct.