Real-time 3D rendering with hatching

We present an approach for real-time pen-and-ink hatching renderings on large scenes. Starting with 3D models including photorealistic textures and materials, we aim to propose a solution that produces hatched renderings. As we consider scene objects described as polygonal meshes with their own textures, we produce once hatching patterns at different tones and resolutions considering the material of each object. To achieve that, we create a flow direction map per texture pixel, using contour characteristics extracted from the original texture and then interpolated. Stroke trajectories are thus generated depending on the flow direction and using B-splines, providing tones from light-to-dark. Tones are then stored in a mutli-resolution tonal art map. Moreover, we aim to overcome the limitations of existing hatching rendering methods by introducing an illumination model, fully implemented on GPU and able to manage three shading types: regular shadow, soft/cast shadow and self-shadowing. Tones and hatching resolutions are, therefore, assigned according to local/global illumination supporting multiple light sources. Our model, both dedicated for 3D static model renderings and 3D model animation, supports model deformations and is also spatially and temporally coherent since it gives continuous hatching strokes during object animations and/or light displacements.