Real-time rendering of proxy based 3D paintings using fin textures

Recent advances in painterly character authoring and rendering let digital artists create characters represented by 3D geometry as well as 3D paint strokes embedded on and around that geometry. Existing methods provide intuitive authoring workflows based on 2D painting gestures, without constraining artists to paint directly on the geometry. Strokes painted on screen outside of the visualized 3D mesh can be embedded in the space around that geometry. The resulting paintings can be rendered in screen space and carry a unique visual style. In this master thesis, we are in particular interested in the 3D painting authoring and rendering process presented in [SSGS11]. Such existing techniques, while providing very unique styles for the offline rendering of 3D animations, were never adapted to interactive or even real-time applications. In this master thesis, we propose the first method to render complex 3D paintings in real-time. This novel method can directly be applied to port stylized rendering to video games. After observing that off-surface paint strokes can be interpreted as volumetric data in the proximity of 3D meshes, we review existing volumetric texture techniques and show that they are not adapted to paint strokes, which can be sparse and have a significant structure which should be preserved. Taking inspiration from shell textures, we provide a method that creates relevant 3D geometry and computes alpha textures to closely approximate 3D paintings using a small number of polygons, that can be rendered in real-time in standard game engines.