Virtually all of today’s games render new frames “from scratch”, meaning that they generally don’t use calculations made prior to that frame (except for temporal anti-aliasing, NVIDIA DLSS, and the occasional post processing technique). But in most games - as in the real world - relatively little changes from frame to frame. If you look outside your window, you might see trees blowing in the wind, pedestrians passing by, or birds flying in the distance. But the majority of the scene is unchanged. The main thing that changes is your point of view.

Some objects will indeed change appearance as you change your point of view - notably those which are glossy or shiny. But most objects will actually change very little as you move your head, and as such, it’s a waste of precious GPU cycles to keep recalculating the same exact colors that make up those objects every frame. Picture, for example, a wooden telephone pole - regardless of your head and eye position, it looks essentially the same.

By using Sampler Feedback, we can more efficiently shade those objects at a lower rate (say, every third frame, or perhaps even lower than that) and reuse the object’s colors (or “texels” as they’re referred to) as calculated in previous frames. This notion of work reuse can be used for ray tracing, especially in the case of global illumination, which is a common example of a slow-changing and very expensive shading computation.

For more info on the tech behind the tech, head here.