Research Interests

Parallel Rendering

Fri, 21 Dec 2007 22:48:05 +0100

In this project we develop novel parallel rendering algorithms and systems.

Point Based Graphics

Fri, 5 Oct 2007 22:28:06 +0200

In this project we develop novel point-based rendering methods based on object-space point interpolation of densely sampled surfaces. We introduce the concept of a transformation-invariant covariance matrix of a set of points which can efficiently be used to determine splat sizes in a multiresolution point hierarchy. We also analyze continuous point interpolation in object-space, and we define a new class of parametrized blending kernels as well as a normalization procedure to achieve smooth blending. Furthermore, we present a hardware accelerated rendering algorithms based on texture mapping and a-blending as well as programmable vertex- and pixel-shaders. Furthermore, we introduce a novel deferred blending method that supports rendering of transparent point surfaces, including multi-layer reflection and refraction effects, and single-pass rendering of point surfaces.

Multiresolution Triangle Strips

Sat, 22 Mar 2003 22:55:52 +0100

In this project we address simple and efficient methods to dynamically manage and generate efficient triangle strips for real-time view-dependent multiresolution meshing and rendering. Progressive view-dependent triangle mesh simplification and rendering is an important concept for interactive visualization environments. To minimize the rendering cost, triangle meshes are simplified to the maximal tolerated perceptual error. A further savings can be gained by using hardware optimized rendering primitives such as triangle strips. However, triangle strips have not been used in the past successfully in interactive multiresolution meshes due to the costs involved with maintaining the coherency of the strips in the dynamically changing mesh. We introduce novel dynamic triangle stripping data algorithms and data structures that are practical for use with multiresolution LOD meshes. DStrips is aimed at preserving pre-computed triangle strips through changes in the mesh and generating reasonably good triangle strips in real-time. Furthermore, this data structure and algorithm can easily be adapted to any multiresolution mesh which has a face-to-edge/edge-to-face mapping. Other solutions include the generation of single-strip triangulations for interactive rendering as well as a novel hierarchyless mesh simplification, stripification and compression method.

Terrain Visualization

Tue, 22 Oct 2002 23:00:04 +0200

Real-time rendering of triangulated digital elevation models (DEMs) is of continuing interest in various mapping and geo-visualization applications. However, efficient interactive visualization of very large scale grid digital elevation models is a very challenging problem. The graphics load must be controlled by an adaptive surface triangulation, and by taking advantage of different levels of detail (LODs). Furthermore, the management of the visible scene requires efficient access to the out-of-core terrain database. We propose approaches and visualization systems for multiresolution view-dependent adaptive terrain triangulation, dynamic scene management and spatial data handling. The LOD triangulation algorithms are based on the restricted quadtree triangulation. Furthermore, we present new algorithms based on the restricted quadtree triangulation. These include among others exact error approximation, multiresolution error saturation, out-of-core effective data clustering, progressive meshing, performance optimizations and spatial access.

Mesh Simplification and Rendering

Thu, 22 Mar 2001 23:03:47 +0100

In this project we developed an optimized view-dependent meshing framework for adaptive and continuous level-of-detail (LOD) rendering in real-time and from out-of-core for large data sets. Multiresolution triangle mesh representations are an important tool for adapting triangle mesh complexity in real-time rendering environments. Ideally for interactive visualization, a triangle mesh is simplified to the maximal tolerated perceptual error, and thus mesh simplification is view-dependent. This paper introduces an efficient hierarchical multiresolution triangulation framework based on a half-edge triangle mesh data structure, and presents an optimized computation of several view-dependent error metrics within that framework providing conservative error bounds. The presented approach called FastMesh, is highly efficient both in space and time cost, and it spends only a fraction of the time required for rendering to perform the error calculations and dynamic mesh updates.

Multiresolution Isosurface Extraction

Sun, 22 Oct 2000 23:07:29 +0200

Multiresolution methods are becoming increasingly important tools for the interactive visualization of very large data sets. Multireso-lution isosurface visualization allows the user to explore volume data using simplified and coarse representations of the isosurface for overview images, and finer resolution in areas of high interest or when zooming into the data. Ideally, a coarse isosurface should have the same topological structure as the original. The topological genus of the isosurface is one important property which is often ne-glected in multiresolution algorithms. This results in uncontrolled topological changes which can occur whenever the level-of-detail is changed. The scope of this paper is to propose an efficient tech-nique which allows preservation of topology as well as controlled topology simplification in multiresolution isosurface extraction.

Progressive Mesh Compression

Mon, 22 Mar 1999 23:11:52 +0100

Most systems that support the visual interaction with 3D models use shape representations based on triangle meshes. The size of these representations imposes limits on applications, for which complex 3D models must be accessed remotely. Techniques for simplifying and compressing 3D models reduce the transmission time. Multi-resolution formats provide quick access to a crude model and then refine it progressively. Unfortunately, compared to the best non-progressive compression methods, previously proposed progressive refinement techniques impose a significant overhead when the full resolution model must be downloaded. The CPM (Compressed Progressive Meshes) approach proposed here eliminates this overhead. It uses a new technique, which refines the topology of the mesh in batches, which each increase the number of vertices by up to 50%. Less than an amortized total of 4 bits per triangle encode where and how the topological refinements should be applied. We estimate the position of new vertices from the positions of their topological neighbors in the less refined mesh using a new estimator that leads to representations of vertex coordinates that are 50% more compact than previously reported progressive geometry compression techniques.