Ray-Traced Reflections, Shadows, AO, and Global Illumination
The impact of ray-traced shadows on both quality and performance is quite subtle. They basically make the shadows sharper and more detailed and can have an almost unnoticeable impact on visual fidelity in some cases. As always, ray-traced reflections have the most obvious impact on quality:
It’s worth noting that while the baked-in (cube-mapped) reflections do account for a number of rather glossy reflections without RT, they’re quite inaccurate and don’t account for the dynamic lighting present in the scene. Most notably, areas that should have been completely dark also cast reflections in the case of the former. In this particular scene, ambient occlusion has the most notable impact on quality due to the lack of sunlight in the scene.
In most well-lit scenes, RT reflections are easily the most prominent easily distinguished, even if you have screen-space reflections by default:
The blocks are quite glossy, and as a result, reflecting. Due to this, ray-traced reflections affect every aspect of the scene from the silhouette of the blocks to shadows (cast on the ground below the block structure) to the lighting and even transparency. Followed by reflections, ray-traced global illumination is the most noteworthy effect used in the game. The indirect bounces of light (diffuse/indirect lighting) lights up many nooks and crannies that would have otherwise been dim:
Since the blocks often result in a very irregular silhouette, global illumination lights up more surfaces than it usually would have. Ambient occlusion and shadows have a lesser impact and in most cases, the former basically offsets the excessive lighting in corners:
Ray-traced comparisons continue on the next page…