It's surprisingly detailed considering the low probe density.
It's also practically completely free as its trivial to calculate the radiance in the same shader as the irradiance per texel.

The radiance cache works by storing another layer of texels on the probe. The new texels store the direct radiance coming into their direction, no cos convolve.

When shading rtgi ray hits, i sample the radiance of the 8 closest probes by projecting the radiance back onto the hit ws position.

Experimenting more with hybrid probe and per pixel traced gi.

I now use a radiance cache to shade per pixel ray trace hits.

It saves a lot of performance and the quality is very close to proper hit shading.

Roughly saving ~30-70% of performance for rtgi (local lights make this verrry worthwhile).

perf is not too great now, probes take around 500us to update, 600us to eval screen irradiance.
Rtgi replaces the eval screen irradiance but takes around 2-3ms now.

Goal is to shoot short traces from pixels (up to maybe 15 meters).

On miss the ray would read the probe volume radiance in the rays direction.

The shorter raylength improves performance immensly.

This hybrid RTGI/probe GI is something that i believe could be very performant and pretty.

Started to experiment with raytraced diffuse gi.
My probe GI works well but it just can not represent fine details with good performance/memory usage.

AO helps it a lot i want even more.

Most of the work on RTGI is denoising, very interesting work.

Here the current state: Probes only vs RTGI:

Great stuff 😍

Yoo, timberdoodle is in there. Great projects all around :)

It’s Timberdoodle time 💛🪶🥔

American Woodcock in Bryant Park, NYC, March 2025

The tech and graphical advancements in Assassin's Creed Shadows are mighty impressive: Micropolygon geometry, fluid wind simulations, ray traced global illumination and so much more. How do they all work and compare to AC games of the past? Find out in my video below!
youtu.be/nhFkw5CqMN0

Thread divergence during constant buffer reads can have a big perf impact, this presentation discusses how to detect this on NVidia GPUs using GPU Trace and Shader profiler. Also shows how useful access to ISA is for understanding what the shader does under the hood. www.youtube.com/watch?v=HSsP...

While watching all the trailers from the Sony State of Play I could not help but notice that 90% of the games shown are Unreal Engine games... with each new scene/effect/character shown it is hard not to think "that will probably stutter on PC".

Illume

Thanks to a lot of colleagues' great work, happy to share Vulkan samples for RTX Mega Geometry. They should run on all RTX GPUs using today's new drivers

github.com/nvpro-sample...

github.com/nvpro-sample...

github.com/nvpro-sample...

github.com/nvpro-sample...

firefox + duckduckgo is pretty solid

somehow, i know that this is correct

the warping of the octahedral mapping means that this is not an ideal way to sample in all cases as sometimes the texel distances are much shorter than in other areas of the probe.
But generally, this does not seem to cause issues.

this is a color coded debug view showing the debugged depth texel (red) and the weight it assigns to all the trace results (green).

As you can see, the weights become 0 nearly immediately.
Sampling a texel area of 6x6 for this resolution is more than enough to get all valid traces.

The trick is to trace rays into a octahedral trace result texture per probe.
The texel update threads can then narrow the area of the trace result texture to consider. For visibility updates, a texel area of only 6x6 contains all relevant samples. 6x6 is 7 times less loop iterations compared to 256.

One of the biggest changes and optimizations i made to my DDGI impl is how probe texels are updated.
Instead of all texels looping over all rays per probe, each texel only checks out relevant rays.

This is a big performance gain with high ray counts (>256) and good depth resolutions of 16x16.

something I've been thinking about recently: could object-space shading be the key to mitigating artifacts from temporal techniques? accumulating data over time in "shade space" rather than camera frame that flails around.
www.oxidegames.com/wp-content/u...

out of curiosity how do you even do sfinae in hlsl, i thought the templates arent powerful enough to do it?

Graphics Programming weekly - Issue 375 - January 19th, 2025 www.jendrikillner.com/post/graphic...

atm its just the raw ddgi probes where i reduce the cos weight for ray directions per sample to a narrow angle.

I wanna play with sh but didnt come to that yet.

The sampling cost of sh seems kinda hefty considering i interpolate 8 probes per pixel