sc94597 on 16 August 2026
Technically there is still ray-tracing in Software Lumen, it's just the rays are traced against Signed-Distance-Fields, which are approximate volumetric representations of the scene geometry. That's why it is less accurate. Hardware lumen works against actual scene geometry (or a very close representation of it, i.e Nanite fallback meshes) because it has available the specialized hardware to accelerate it for real-time workloads.
Example of an SDF from Wikipedia.
The difference is primarily the data structures/geometric representation being traced against. In Software Lumen you have the SDF representation, while in Hardware Lumen there is the TLAS/BLAS BVH.
Last edited by sc94597 - on 16 August 2026
