| Sample-based primitives, such as volumes from medical imaging and scientific simulation, images taken from the real world, and points from 3D range scanners, have been widely used in visualization and computer graphics. With advances in 3D scanning technologies and scientific simulations, irregular samples are becoming increasingly important. How to organize and render these irregular samples is an important and challenging research problem.; This thesis describes the O-buffer, a new modeling and rendering primitive, and its associated algorithms and applications. The 2D or 3D O-buffer is in essence a conventional image or a volume, respectively, except that samples are not restricted to a regular grid. A sample position in the O-buffer is recorded as an offset to the grid point of a regular base grid (hence the name O-buffer). The offset is typically quantized for compact representation and efficient rendering.; O-buffers can greatly improve the modeling power of images and volumes. The O-buffer emancipates pixels and voxels from regular grids. It is a semi-regular structure, which lends itself to efficient construction and rendering. Image quality can be improved by storing more spatial information with samples and by avoiding multiple resamplings and delaying reconstruction to the final rendering stage. Using O-buffers, more accurate multi-resolution representations can be developed for images and volumes. It can also be exploited to represent and render unstructured primitives, such as points, particles, and curvilinear or irregular volumes. The O-buffer is therefore a uniform representation for a variety of graphics primitives and supports mixing them in the same scene.; We present a family of new modeling and rendering primitives under the general umbrella of "O-buffer". Included among these are 2D O-buffers, 3D O-buffers, nonuniform O-buffers, adaptive O-buffers, layered-depth O-buffers, hierarchical O-buffers, O-buffer trees, offset distance fields and unified distance fields. In addition, efficient construction and rendering algorithms for O-buffers are presented. The O-buffer is further used as a framework to attack a wide range of problems in image-based rendering, point sample rendering, volume rendering, and solid modeling. |
