Efficient rendering of multiresolution meshes with guaranteed image quality

Abstract

Recently, output-sensitive rendering algorithms have gained a lot interest. While some years ago the number of triangles describing a scene was smaller than the number of pixels on the screne, this relation has changed to the opposite. The size of the models has become significantly larger while the screen resolution remained more or less constant. One way to get output-sensitivity, is the view-dependent use of multiresolution models. The key idea is to determine the lowest resolution for each part of the object that is necessary to get good images that are visually indistinguishable from rendering the original mesh. To take care of the illumination of the objects there are approaches that use cones of normal vectors to perform illumination dependent selective refinement. This allows the correct rendering of highlights and transitions between lit and unlit areas of an object. The drawback of these approaches is that using only the normal cone for the detection gives only a very poor criteria to detect the problematic cases. Therefore, too much refinement has to be performed which in most cases prevents real time update rates between successive frames.In this paper we describe a new approach for better estimation of normal deviations between different levels of detail. This allows for accurate lighting with a minimum number of triangles.

Perceptually guided simplification of lit, textured meshes

“…[Cohen et al 1998] track the parametric surface distortion to derive a screen-space bound on the movement of color (represented by a texture map) and lighting (represented by a normal map) across the surface. Similar work by [Schilling and Klein 1998], and later work by the same authors [Klein and Schilling 1999 ], also deserves mention. In the former, they account for texture distortion using a surface mapping technique similar to that of Cohen et al; in the latter, they account separately for lighting artifacts in vertex-lit models using cones that bound the normals and halfway vectors.…”

“…Given the lighting model, we can bound the luminance of the diffuse contribution by calculating the vector encompassed by the shading normal cone that is closest in direction to L and the vector furthest in direction from L. Similarly, we find the range of specular contribution using the halfway vector. Note that this computation is similar to that of [Klein and Schilling 1999 ].…”

Towards Perceptual Simplification of Models with Arbitrary Materials

“…They also developed an illumination‐based simplification algorithm [KSS98], where normal deviation is used for the accurate simplification of surfaces with specular highlights that are rasterized with Gouraud shading. They also proposed an algorithm for lighting‐dependent refinement of multiresolution meshes based on normal cones [KS99]. Unfortunately, neither of these two approaches can be used for textured surfaces.…”

Perceptually guided simplification of lit, textured meshes

“…View-dependent simplification research has also emphasized silhouette preservation; for example, [Luebke and Erikson 1997] enforce a tighter screen-space error threshold for silhouette regions than interior regions. Similarly, the presence and movement of specular highlights across a surface are known to provide important clues to its shape, so [Xia and Varshney 1996] and [Klein and Schilling 1999] describe view-dependent simplification schemes that preserve detail where such highlights are likely to appear. Many researchers have used heuristics and user-specified weights to balance the importance of geometric fidelity during simplification against preservation of appearancerelated attributes, such as color, normals, and texture coordinates [Garland and Heckbert 1998, Erikson and Manocha 1999, Hoppe 1999.…”