This approach was originally developed by Alex Sanikov for Path of Exile 2.
Of course in PoE2 it's used in full 3d.
The benefit of this approach is that you get global illumination with a constant cost for the entire scene and because it doesn't use any temporal acculation, it has zero latency as well.
There is no traditional "lighting" added to these two effects. The light on the nearby surfaces is indirect light from the GI solution that you get for free by just spawning the particles. That means all effects just naturally emit light with no extra work from artists.
On my GPU (which is admittedly a 4090) the GI solution runs in 0.8ms for a 4k scene in "High" quality. This is exactly what it will always cost, no matter what scene you choose.
From what I understand, PoE2 has a fixed-perspective camera, so radiance is calculated in screenspace (2D) as an optimization (and not using a 3D texture). It would be interesting to see how the performance of this technique scales to full 3D, as that would be significantly more expensive / require a lower-resolution voxelization of the scene.
There's ambient occlusion that computes light intensity with high spatial resolution, but completely handwaves the direction the light is coming from. OTOH there are environment maps that are rendered from a single location, so they have no spatial resolution, but have precise light intensity for every angle. Cascade Radiance observes that these two techniques are two extremes of spatial vs angular resolution trade-off, and it's possible to render any spatial vs angular trade-off in between.
Getting information about light from all angles at all points would cost (all sample points × all angles), but Radiance Cascades computes and combines (very few sample points × all angles) + (some sample points × some angles) + (all sample points × very few angles), which works out to be much cheaper, and is still sufficient to render shadows accurately if the light sources are not too small.
So on my webcam there is a cover but it doesn't fully cover the webcam. So this technology would be able to infer something from the radiance of the light seeping in around the edges?
This is a rendering technique designed for real-time graphics, and it's not applicable to that kind of image analysis. It does what has already been possible with ray tracing, but using an approximation that makes it suitable for real-time graphics.
However, the technique has been used to speed up astrophysics calculations:
This approach was originally developed by Alex Sanikov for Path of Exile 2.
Of course in PoE2 it's used in full 3d.
The benefit of this approach is that you get global illumination with a constant cost for the entire scene and because it doesn't use any temporal acculation, it has zero latency as well.
This means you can rely on it as the lighting for fast effects. For example: https://www.youtube.com/watch?v=p1SvodIDz6E
There is no traditional "lighting" added to these two effects. The light on the nearby surfaces is indirect light from the GI solution that you get for free by just spawning the particles. That means all effects just naturally emit light with no extra work from artists.
On my GPU (which is admittedly a 4090) the GI solution runs in 0.8ms for a 4k scene in "High" quality. This is exactly what it will always cost, no matter what scene you choose.
From what I understand, PoE2 has a fixed-perspective camera, so radiance is calculated in screenspace (2D) as an optimization (and not using a 3D texture). It would be interesting to see how the performance of this technique scales to full 3D, as that would be significantly more expensive / require a lower-resolution voxelization of the scene.
From offhand comments I've read, you are right. It's not practical for 3D.
In the age of PoE is Diablo even relevant anymore?
The guy that developed the technique works on Path of Exile. They’re using it for POE2, he gave an awesome talk about it here
https://youtu.be/TrHHTQqmAaM?si=xrW0XT2lsGHqUYY_
I'm trying to understand the basic idea of Radiance Cascades (I don't know much about game development and ray tracing).
Is the key idea the fact that light intensity and shadowing require more resolution near the light source and lower resolution far from it?
So you have higher probe density nearby the light source and then relax it as distance increases minimising the number of radiance collection points?
Also using interpolation eliminates a lot of the calculations.
Does this make any sense? I'm sure there's a lot more detail, but I was looking for a bird's eye understanding that I can keep in the back of my mind.
Essentially yes.
There's ambient occlusion that computes light intensity with high spatial resolution, but completely handwaves the direction the light is coming from. OTOH there are environment maps that are rendered from a single location, so they have no spatial resolution, but have precise light intensity for every angle. Cascade Radiance observes that these two techniques are two extremes of spatial vs angular resolution trade-off, and it's possible to render any spatial vs angular trade-off in between.
Getting information about light from all angles at all points would cost (all sample points × all angles), but Radiance Cascades computes and combines (very few sample points × all angles) + (some sample points × some angles) + (all sample points × very few angles), which works out to be much cheaper, and is still sufficient to render shadows accurately if the light sources are not too small.
This article unfortunately presupposes understanding of (ir)radiance probes, a topic on which there isn't even a Wikipedia article...
So on my webcam there is a cover but it doesn't fully cover the webcam. So this technology would be able to infer something from the radiance of the light seeping in around the edges?
This is a rendering technique designed for real-time graphics, and it's not applicable to that kind of image analysis. It does what has already been possible with ray tracing, but using an approximation that makes it suitable for real-time graphics.
However, the technique has been used to speed up astrophysics calculations:
https://arxiv.org/pdf/2408.14425
They're waiting for you, Gordon. In the test chamber.
>it's saturday morning 1998 and you are in your coziest sleepwear, on the computer in the living room.
I WANT TO GO BAAACK!
> In the test chamber.
Flashbacks to sitting the GRE
Resonance cascade?
A gamble, but we needed the extra resolution.