Hierarchical Image-Based Rendering using Texture Mapping Hardware

Multi-layered depth images containing color and normal information for subobjects in a hierarchical scene model are precomputed with standard z-buffer hardware for six orthogonal views. These are adaptively selected according to the proximity of the viewpoint, and combined using hardware texture mapping to create reprojected output images for new viewpoints. (If a subobject is too close to the viewpoint, the polygons in the original model are rendered.) Specific z-ranges are selected from the textures with the hardware alpha test to give accurate 3D reprojection. The OpenGL color matrix is used to transform the precomputed normals into their orientations in the final view, for hardware shading

Simplifying the Representation of Radiance from Multiple Emitters

International audienceIn recent work radiance function properties and discontinuity meshing have been used to construct high quality interpolants representing radiance. Such approaches do not consider the combined effect of multiple sources and thus perform unnecessary discontinuity meshing calculations and often construct interpolants with too fine subdivision. In this research we present an extended structured sampling algorithm that treats scenes with shadows and multiple sources. We then introduce an algorithm which simplifies the mesh based on the interaction of multiple sources. For unoccluded regions an a posteriori simplification technique is used. For regions in shadow, we first compute the maximal umbral/penumbral and penumbral/light boundaries. This construction facilitates the determination of whether full discontinuity meshing is required or whether it can be avoided due to the illumination from another source. An estimate of the error caused by potential simplification is used for this decision. Thus full discontinuitymesh calculation is only incurred in regions where it is necessary resulting in a more compact representation of radiance

ACCURATE AND RELIABLE ALGORITHMS FOR GLOBAL ILLUMINATION

The simulation of global illumination is one of the most fundamental problems in computer graphics, with applications in a wide variety of areas, such as architec-ture and lighting design, computer-aided design, and virtual reality. This prob-lem concerns the transport of light energy between reflective surfaces in an en-vironment. During the past decade, radiosity has become the method of choice for simulating global illumination in diffuse environments. Despite much recent progress in efficiency and applicability of radiosity methods, there are several very important open issues remaining: 1) Radios-ity images suffer from many visual artifacts, resulting from lack of reliable au-tomatic discretization algorithms; and 2) Current radiosity algorithms do not provide the user with guaranteed bounds or reliable estimates of the approxi-mation errors. As a result, current radiosity systems require very careful and time-consuming user intervention in the discretization process, and the accu-racy of the resulting solutions can only be assessed by visual appearance. This thesis presents new radiosity algorithms for diffuse polyhedral envi