RMIP: Displacement ray-tracing via inversion and oblong bounding

SIGGRAPH Asia 2023 (conference)

A scene where most geometric content comes from high-resolution displacement mapping. The base geometry and the 4k displacement maps tiled on it are shown on the right. Our proposed method achieves 11x faster path tracing than TFDM [Thonat et al. 2021] while consuming 3x less memory.


High-performance ray tracing of triangle meshes equipped with displacement maps is a challenging task. Existing methods either rely on pre-tessellation, taking full advantage of the hardware but with a poor memory/quality tradeoff, or use custom displacement-centric acceleration structures, preserving all the geometric details but being orders of magnitude slower. We introduce a method that efficiently probes the displacement-map space to find ray-surface intersections without relying on pre-tessellation. Our method combines inverse displacement mapping and on-the-fly surface-bound computation. It employs a novel data structure that provides tight displacement bounds over rectangular regions in the displacement-map space. We demonstrate the effectiveness of our approach in a production GPU path tracer. It can achieve over an order of magnitude speed-up in render time compared to state of the art in the most challenging real-time path-tracing scenarios, while maintaining a low memory footprint.

Downloads and links


Supplemental video

Fast-forward video

BibTeX reference

  author = {Th\'{e}o Thonat and Iliyan Georgiev and François Beaune and Tamy Boubekeur},
  title = {Perceptual error optimization for Monte Carlo animation rendering},
  booktitle = {ACM SIGGRAPH Asia 2023 Conference Proceedings},
  year = {2023},
  doi = {10.1145/3610548.3618146},
  isbn = {979-8-4007-0315-7/23/12}