Improved Shader and Texture Level of Detail Using Ray Cones

In real-time ray tracing, texture filtering is an important technique to increase image quality. Current games, such as Minecraft with RTX on Windows 10, use ray cones to determine texture-filtering footprints. In this paper, we present several improvements to the ray-cones algorithm that improve image quality and performance and make it easier to adopt in game engines. We show that the total time per frame can decrease by around 10% in a GPU-based path tracer, and we provide a public-domain implementation.

Errata:

• Page 13, three lines from bottom, should say "w = 2r = 2t \tan (\alpha / 2)", i.e., add the factor "/ 2". Same with the expression for the radius, which should be "r = t \tan (\alpha / 2)".
• Figure 10: the angle "alpha" should be "alpha / 2".
• Page 16, next to last sentence above Listing 1 should be "\texttt{SampleGrad}(2\vc g_1, 2\vc g_2)", i.e., add two factor of 2 inside the parenthesis.