Hybrid fur rendering: combining volumetric fur with explicit hair strands

Abstract

Hair is typically modeled and rendered using either explicitly defined hair strand geometry or a volume texture of hair densities. Taken each on their own, these two hair representations have difficulties in the case of animal fur as it consists of very dense and thin undercoat hairs in combination with coarse guard hairs. Explicit hair strand geometry is not well-suited for the undercoat hairs, while volume textures are not well-suited for the guard hairs. To efficiently model and render both guard hairs and undercoat hairs, we present a hybrid technique that combines rasterization of explicitly defined guard hairs with ray marching of a prismatic shell volume with dynamic resolution. The latter is the key to practical combination of the two techniques, and it also enables a high degree of detail in the undercoat. We demonstrate that our hybrid technique creates a more detailed and soft fur appearance as compared with renderings that only use explicitly defined hair strands. Finally, our rasterization approach is based on order-independent transparency and renders high-quality fur images in seconds.

Combined volume and surface rendering with global illumination caching

“…Their approach expects a segmented volume as well as volumetric and mesh representations of objects and allows users to render the final image in the desired style. Andersen et al [1] present hybrid fur rendering where they join rendering of explicit hair strand geometry and rendering of volume texture of hair densities using ray marching of a prismatic shell volume with dynamic resolution. Their method creates a more detailed and soft fur appearance than either of the individual approaches.…”

CGI 2016 Editorial (TVCJ)

“…The two next papers by Huang et al [3] and Zhou et al [4] focus on virtual garment stretching and face generation for virtual characters. The papers by Bao et al [5] and Andersen et al [6] are about hair and fur simulation. The next paper by Papaefthymiou et al [7] is on a geometric algebra for character animation and the last paper of this topic from Skola et al [8] studies the effect of body ownership.…”