At Siggraph 2015, Remedy Entertainment’s Ari Silvennoinen and Ville Timonen hosted a speech titled “Multi-Scale Global Illumination in Quantum Break,” shedding some light on the advanced techniques used in the upcoming Xbox One exclusive’s lighting (yes, I made a pun).
The presentation slides were chock.full of interesting pictures and comparisons between the various effects and their intermediate stages.
First of all, we get three lovely screenshots:
Here we get a breakdown of the global illumination elements, starting with a final picture:
Screen Space Lighting:
Large Scale Lighting:
A comparison between reflection probes on and off (including side-by-side).
Placement of the probes:
Seamless Interpolation (allows to illuminate dynamic and static objects with the same global illumination data):
To avoid light leaking, the trilinear interpolation weight is multiplied with a geometry term, which takes the surface normal into account.
Here’s a final image with all the global illumination features.
Here’s the same image without global illumination, using only screen space effects and ambient lighting.
The same comparison, showing only the lighting at the bottom.
Below you can see a comparison between a picture showing only direct lighting and global illumination. At the bottom you can see two pictures showing only indirect lighting. The pre-rendered reference is compared with the real-time result, and they’re almost identical.
Global illumination is also used to implement volumetric lighting.
A comparison between the results using global illumination and constant ambient light.
Below you can see the global illumination diffuse occlusion only, compared with the screen space diffuse color added afterwards.
Here’s a Monarch operative with screen space ambient occlusion applied. Before you go up in flames, the speech notes clarify that the final image is in 1080p, but screen-space lighting is evaluated at 720p. That’s actually pretty normal in game development.
The same scene we’ve seen before quite a few times (from a different angle), showing only screen space ambient occlusion.
Temporal filtering is used to mitigate noise. You can see the difference below.
Below you can see the screen space diffuse lighting compared with a final image.
Here are three comparisons with screen space ambient occlusion and screen space diffuse lighting turned on and off.
Screen space reflections: global illumination specular occlusion and screen space specular.
Screen space reflection occlusion with temporal filtering:
A comparison between the screen space reflections only, and the finished image:
Here’s a comparison with screen space reflection occlusion and screen space reflections on and off.
Various degrees of smoothness for reflections are supported:
Compute shaders allow sharing of ray data for a better result.
Lighting is, without a doubt, one of the best elements of Quantum Break. It’s quite obvious that Remedy went to painstaking efforts to reach the best results.
It’ll definitely be interesting to see the final game when it’ll come out on April 5th, 2016. What we’ve seen so far definitely looks promising.