Lighting techniques at Knack (PS4)

• I'm interested in the lighting techniques (Indirect diffuse lighting, reflections) in this game.

• Links of Knack PS4 gameplay
  • http://www.ign.com/videos/2013/08/21/15-minutes-of-knack-gameplay
  • http://www.youtube.com/watch?v=iG98LuaYj_g

Brick Map for Diffuse GI

• ( I will add several explanation about BrickMaps at here.)
• Baked lightMaps maps aren't used in this game.
• Tai Yamaguchi (山口太) who is a lead graphics programmer at SCE said that Knack uses "Brick Map" for diffuse GI in CEDEC 2013.
• Brick Maps
  • http://staffwww.itn.liu.se/~stegu/TNM022-2004/PRMan-docs/prman_technical_rendering/AppNotes/baking3d.html

• Proceedings of "Game graphics maniacs" in CEDEC 2013 (Japanese)
  • http://www.z-z-z.jp/BLOG/log/eid1031.html

Ambient Occlusion

• Knack uses SSAO which is similar to Alchemy AO.
• And it also uses primitive based AO and height based AO which is a similar technique used in Asassin's Creed 3.
• Baked ambient occlusion maps are not used in this game.

Parallax corrected cubemaps

• Parallax corrected cubemaps is used to correct the reflection vector based on parallax effects.
• ( This technique is first used in Remember ME. )

Local reflection for realtime reflection

• To calculate the dynamic reflections of scene, local reflection which computes the reflection vector and do ray-marching toward the depth buffer in screen space is used in this game.
• ( This technique is first developed by Crytek and used in Crysis2, Ryse Son of Rome and Killzone Shadow Fall. )

• But local reflection has some constraints. For example, it cannot get reflection information if the reflection vector hit outside the screen.
• The image below shows the artifacts of the local reflection. This black area occurs because the reflection ray hit outside the screen.

Conclusion

• Knack uses several state of art lighting techniques.
• Personally, I am interested in using BrickMaps for diffuse GI which archive beautiful indirect lighting in Knack.