Ray Tracing Animated Displaced Micro-Meshes

We present a new method that allows efficient ray tracing of virtually artefact-free animated displaced micro-meshes (DMMs) [MMT23] and preserves their low memory footprint and low BVH build and update cost. DMMs allow for compact representation of micro-triangle geometry through hierarchical encoding of displacements. Displacements are computed with respect to a coarse base mesh and are used to displace new vertices introduced during 1 : 4 subdivision of the base mesh. Applying non-rigid transformation to the base mesh can result in silhouette and normal artefacts (see Figure 1) during animation. We propose an approach which prevents these artefacts by interpolating transformation matrices before applying them to the DMM representation. Our interpolation-based algorithm does not change DMM data structures and it allows for efficient bounding of animated micro-triangle geometry which is essential for fast tessellation-free ray tracing of animated DMMs.