At SIGGRAPH 2025, Intel, Disney Animation, Disney Research Studios, and Chaos are doing a course on the nitty gritty details of implementing path guiding methods in 3 production renderers: Blender's Cycles, Disney's Hyperion, and Chaos' Corona. I helped write the course notes: 80 pages of great stuff! Coming soon.

https://s2025.conference-schedule.org/presentation/?id=gensub_268&sess=sess205

All HPG 2025 papers are now available on the EG digital library.
CGF papers: https://diglib.eg.org/handle/10.2312/3607201
Conference papers: https://diglib.eg.org/handle/10.2312/3607202
It has been a huge honor to act as HPG papers chair and guest editor and I look forward to an exciting program in Copenhagen.

Spherical harmonics are widely used in graphics. Ever wondered how to compute their derivatives? My HPG 2025 poster shows that it is basically free.
It also comes with a code generator for C, C++, Python, GLSL and HLSL to compute SH with derivatives.
https://momentsingraphics.de/HPGPoster2025.html

My webpages https://momentsingraphics.de and https://ultimate3d.org have migrated to a new server. If you notice anything broken, please let me know.

4 weeks to the HPG papers deadline (and 3 to the abstract deadline).
Our call for posters, Hot3D and the student competition are also online and @c0de517e is confirmed as our first keynote speaker.
https://highperformancegraphics.org/2025/program/cfp/

@TomF Real but we are not good at seeing it when it's monochromatic. I saw Alex Wilkie's purple laser pointer.

Alban Fichet and I published a JCGT paper on lossy compression of spectral images, i.e. images with 1 channel per wavelength 🌈.
TL;DR: Cosine transform the spectrum of each pixel, normalize by mean brightness and compress the resulting channels using JPEG XL.
https://momentsingraphics.de/JCGT2025.html
https://jcgt.org/published/0014/01/04/

The High-Performance Graphics 2025 papers deadline is 8 weeks from now on April 14 (abstract deadline is April 7).
I hope your research is coming along nicely. I can't wait to see what you've been working on and to meet at HPG in Copenhagen, June 23-25.
https://highperformancegraphics.org/2025/program/cfp/

Judging by the Blackwell whitepaper, RTX Mega Geometry is an implementation of ideas from this HPG 2023 paper by Carsten Benthin and me. It is cool to see this broadly deployed so soon. Hopefully, cross-vendor standardization will be just as swift.
https://mastodon.gamedev.place/@MomentsInGraphics/110600733394779367

@pekkavaa Glad you liked it.
Regarding irradiance, you may very well want to use max(0,n⋅ω) instead of |n⋅ω|. Especially when computing diffuse shading, that is the right thing to do. But then again, if you have a closed mesh, radiance below the surface should be zero anyway.
For the definition of radiant flux, it makes more sense to work with |n⋅ω| because I define the flux as a property of the surface A, without saying which side is outside.
Maybe I'll clarify that alongside some update.

My new blog post explains spectral radiometric quantities, photometry and basics of spectral rendering. This is part 2/2 in a series on radiometry. Learn what it means when a light bulb has 800 lumen and how your renderer can account for that.
https://momentsingraphics.de/Radiometry2Photometry.html

You cannot get physically-based rendering right without understanding radiometry. My new blog post explains it all, relying on familiar concepts from rendering algorithms as much as possible.
Part 2 will come next week.
https://momentsingraphics.de/Radiometry1Backwards.html

All materials for the path tracing lectures are on the TU Delft webpage, but I also wrote a little blog post explaining the relationship to my workshop:
https://momentsingraphics.de/PathTracingLectures.html
This is the workshop that I am talking about in case you missed it:
https://mastodon.gamedev.place/@MomentsInGraphics/109545921737309034

Do you want to learn path tracing? Two lectures that I held at TU Delft are on YouTube now! The 2nd is what I had in mind for part 3 of my PT workshop. No Shadertoy exercises this time, but an open source Vulkan path tracer 🥳.
https://www.tudelft.nl/ewi/over-de-faculteit/afdelingen/intelligent-systems/computer-graphics-and-visualization/education/path-tracing-lecture
https://www.youtube.com/watch?v=UerwiSuIOSY

I am also on Bluesky now:
https://bsky.app/profile/momentsingraphics.bsky.social

I have the honor of being papers chair for High-Performance Graphics 2025, together with Aaron Knoll. We look forward to your submissions on graphics algorithms, hardware and systems.
Abstract deadline: April 7 2025
Papers deadline: April 14 2025
Conference: June 23-25, Copenhagen (colocated with EGSR)
https://highperformancegraphics.org/2025/program/cfp/

@c0de517e I remember Marcos Fajardo in his EGSR 2019 keynote saying that a path tracer developed by Blue Sky Studios was a significant inspiration for Arnold. PBRT v4 chapter 1.6.2 confirms that Blue Sky was very early, pointing out Bunny (1998) as early path traced short.
https://www.youtube.com/watch?v=Gzv6WAlpENA
In terms of feature movies, Sony's Monster House (2006) using Arnold was among the first according to PBRT.

The embedded video players on the Intel webpages for this path tracing workshop are no longer working, so I added direct links to the videos on my blog:
https://momentsingraphics.de/PathTracingWorkshop.html

The embedded video players on the Intel webpages for this path tracing workshop are no longer working, so I added direct links to the videos on my blog:
https://momentsingraphics.de/PathTracingWorkshop.html

@c0de517e I'd be curious to know why you don't believe in ReSTIR.