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Comment by alhirzel | Hacker News Reader

Those interested in this article may be interested in experimenting with the Mitsuba renderer [1]. This is one of the best open-source spectral renderers, and it includes support for RGB and spectral modes (in addition to propagating things like polarization), all in one unified rendering pipeline with CUDA and non-CUDA backends.

[1]: https://www.mitsuba-renderer.org/

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Also worth mentioning Manuka, which is Weta's production spectral renderer. There's a nice overview of the architecture here, which includes a section on their motivations for, and implementation of, spectral light transport:

https://jo.dreggn.org/home/2018_manuka.pdf

OP author here. Thanks for mentioning it, I happen to work at Wētā FX and we are obviously very biased toward spectral rendering and the problems it solves. I often hear people saying that spectral rendering is complicated but it is actually the opposite, mostly everything becomes simplified with it. It, gives, at the very least an elegant first principle based framework to work from.

Another one like this is (was? not sure if it's maintained any more) Lux Render: https://luxcorerender.org/

I played my part in this back in the 2010s maintaining the blender integration, fun times :)

But both the renderer and the integrations got pretty much entirely re-written in the move to GPU compute shortly after that time.

It seems strange that the website of a renderer wouldn’t have any rendered images. What does it look like? Do spectral renderers achieve a better result than traditional rendering methods?

Show me! I want to see the difference!

https://mitsuba.readthedocs.io/en/stable/src/gallery.html

But Mitsuba is not really complete system to make pretty pictures, it is more of a framework for researchers to prototype algorithms etc. So while many state of the art methods have been implemented on top of Mitsuba, not nearly all of them have been merged to the mainline. If you want comparisons then you probably need to look up specific papers to see comparisons for the specific problems they solve.

Better is subjective, but the whole point of spectral rendering is to be more objective. The visual difference is minor and its relevance to film/games is put into question by the artistic post processing that inevitably distorts the final result. There are some effects that “just work” with spectral rendering though, so you might save some hackery there.

Another stand-out feature of Mitsuba is its focus on differentiability. Wenzel Jakob is an absolute rockstar in computer graphics, and his group creates informative demo and explanatory videos for their areas of work. These include:

Differentiable rendering: http://rgl.epfl.ch/publications/Jakob2022DrJit

Volumetric rendering: http://rgl.epfl.ch/publications/NimierDavid2022Unbiased

Optimization of light path choice via AD: http://rgl.epfl.ch/publications/Vicini2021PathReplay

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