Volume painting: incorporating volumetric rendering with line integral convolution (LIC)

This thesis presents an expressive (non-photorealistic) rendering approach created by combining volumetric rendering techniques with the Line Integral Convolution (LIC) in 3D space. Although some techniques that combine volume rendering with the LIC have been introduced in computer graphics, they are mainly used for the scientific visualization fields, such as the visualization of 3D fluid fields. Unlike earlier research, we will focus on artistic representation, which is significantly different than scientific visualization research. We will implement a brush-stroke effect on the implicit surfaces by using the LIC. The implicit surfaces are described as volume datasets that are created by the voxelization of triangular meshes. To acquire smearing effects on the surface we convolve along the vector fields with the densities of the voxels of the datasets. These vector fields are defined by users as texture maps. The final images are rendered with volume ray casting, integrating colors and densities of voxels with Perlin noise along vector fields. The Perlin noise provides randomness and allows us to generate scratches. Smearing effects on the surface of an object create the illusion of 3D brush-strokes as if a painter had created brush strokes on a canvas. The rendering system is implemented using standard C and C++ programming languages. 3D models are then created using Alias MayaTM and TopmodTM.