Fast sphere tracing of procedural volumetric noise for very large and detailed scenes

Abstract Real‐time walk through very large and detailed scenes is a challenge for both content design, data management, and rendering, and requires LOD to handle the scale range. In the case of partly stochastic content (clouds, cosmic dust, fire, terrains, etc.), proceduralism allows arbitrary large and detailed scenes with no or little storage and offers embedded LOD, but the rendering gets even costlier. In this paper, we propose to boost the performance of Fractional Brownian Motion (FBM)‐based noise rendering (e.g., 3D Perlin noise, hypertextures) in two ways: improving the stepping efficiency of Sphere Tracing of general Signed Distance Functions (SDF) considering the first and second derivatives, and treating cascaded sums such as FBM as nested bounding volumes. We illustrate this on various scenes made of either opaque material, constant semi‐transparent material, or non‐constant (i.e.,full volumetric inside) material, including animated content ‐ thanks to on‐the‐fly proceduralism. We obtain real‐time performances with speedups up to 12‐folds on opaque or constant semi‐transparent scenes compared to classical Sphere tracing, and up to 2‐folds (through empty space skipping optimization) on non‐constant density volumetric scenes.