DirectX Raytracing: Microsoft drastically reduces memory

Microsoft extends DirectX Raytracing with Clustered Geometry, Partitioned TLAS, and indirect GPU-driven builds of acceleration structures. The features are part of the Agility SDK 1.722 Preview. In an extreme test documented by Microsoft, the memory requirement for ray tracing acceleration structures drops from 7,519 to 774 MiB. That represents 89.7 percent less memory. In this specific scenario, the measured frame rate rises from 1.2 to 79 FPS.

Ray tracing structures no longer have to be rebuilt from scratch

Traditional ray tracing uses Bottom-Level Acceleration Structures, or BLAS, for geometry and a Top-Level Acceleration Structure above them for the entire scene. With heavily animated or streamed geometry, repeatedly rebuilding these structures can consume significant compute time and memory bandwidth. Clustered Geometry therefore divides geometry into smaller, reusable units. A so-called Cluster Level Acceleration Structure can contain up to 256…