Microsoft is previewing two DirectX features designed to reduce the memory and processing demands of ray tracing: Clustered Geometry and Partitioned TLAS. The company describes the changes as the most significant update to DirectX Raytracing since its introduction in 2018.
According to Microsoft’s testing, the technology reduced ray tracing memory usage from 7.5 GB to 774 MB on an AMD Radeon RX 9070. In the same specialised test environment, performance increased from 1.2 frames per second to 79 fps. The company’s figures suggest a potential memory reduction of up to 90%, without requiring an Nvidia GPU.
Clustered Geometry divides detailed models into groups of up to 256 triangles. Partitioned TLAS applies a similar approach to the wider game scene by separating it into smaller regions. Ray tracing can then focus on the portions of the scene that have changed instead of checking and updating the entire environment every frame.
This approach is intended to simplify the ray tracing data that a system must process and update. However, Microsoft has warned that results will vary between games and that the benefits seen in its test environment will not necessarily be reproduced elsewhere.
The system also requires more temporary scratch memory because of the additional geometry clusters, creating potential implementation challenges for developers. The features are not yet widely available, and Microsoft has not announced when they will reach PC gamers generally.
Developers and users testing the experimental functionality need matching Agility SDK preview headers and runtime, a compatible driver, and Windows Developer Mode.
Sources: PC Gamer.