Current Topics in Computer Graphics 

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Vorträge:

 

TerminVortragender
Titel
27.04.2007Alexander Borst
 4K-Kine - Evaluation von objektiven Videoqualitätmaßen
07.05.2007Robert Grimm
Volume Rendering
14.05.2007Robert Grimm

GPGPU - Introduction / Metaprogramming Frameworks

21.05.2007Alexander Brost
Linear Algebra Methods
04.06.2007 Matthias Schneider Sorting and Searching
11.06.2007  
18.06.2007  
25.06.2007Christian Heckl
 t.b.a.
02.07.2007 Marek Bubala t.b.a.
09.07.2007 Dorothea Malsch t.b.a.
16.07.2007 Christopher Ritter
 Resolution Independent Curve Rendering using Programmable Graphics Hardware

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Folgende Themen stehen zur Auswahl:

Thema: Real-Time GPU Rendering of Piecewise Algebraic Surfaces
(Siggraph 2006)

URL: http://research.microsoft.com/~cloop/

Abstract: We consider the problem of real-time GPU rendering of algebraic surfaces defined by B´ezier tetrahedra. These surfaces are rendered directly in terms of their polynomial representations, as opposed to a collection of approximating triangles, thereby eliminating tessellation artifacts and reducing memory usage. A key step in such algorithms is the computation of univariate polynomial coefficients at each pixel; real roots of this polynomial correspond to possibly visible points on the surface. Our approach leverages the strengths of GPU computation and is highly efficient. Furthermore, we compute these coefficients in Bernstein form to maximize the stability of root finding, and to provide shader instances with an early exit test based on the sign of these coefficients. Solving for roots is done using analytic techniques that map well to a SIMD architecture, but limits us to fourth order algebraic surfaces. The general framework could be extended to higher order with numerical root finding.


Betreuung: Matthias Tessmann

 

Thema: Ambient Occlusion and Edge Cueing to Enhance Real Time Molecular Visualization
(IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS, VOL. 12, NO. 5, SEPTEMBER/OCTOBER 2006)

URL: http://vcg.isti.cnr.it/Publications/2006/TCM06/

Abstract: The paper presents a set of combined techniques to enhance the real-time visualization of simple or complex molecules (up to order of 106 atoms) space fill mode. The proposed approach includes an innovative technique for efficient computation and storage of ambient occlusion terms, a small set of GPU accelerated procedural impostors for space-fill and ball-and-stick rendering, and novel edge-cueing techniques. As a result, the user’s understanding of the three-dimensional structure under inspection is strongly increased (even for still images), while the rendering still occurs in real time.

Betreuung: Frank Enders
Thema: Direct Isosurface Extraction from Scattered Volume Data
(Eurographics/ IEEE-VGTC Symposium on Visualization (2006)

URL: http://www.math-inf.uni-greifswald.de/~paul/publications/

Abstract: Isosurface extraction is a standard visualization method for scalar olume data and has been subject to research for decades. Nevertheless, to our knowledge, no isosurface extraction method exists that directly extracts surfaces from scattered volume data without 3D mesh generation or reconstruction over a structured grid. We propose a method based on spatial domain partitioning using a kd-tree and an indexing scheme for efficient neighbor search. Our approach consists of a geometry extraction and a rendering step. The geometry extraction step computes points on the isosurface by linearly interpolating between neighboring pairs of samples. The neighbor information is retrieved by partitioning the 3D domain into cells using a kd-tree. The cells are merely described by their index and bitwise index operations allow for a fast determination of potential neighbors. We use an angle criterion to select appropriate neighbors from the small set of candidates. The output of the geometry step is a point cloud representation of the isosurface. The final rendering step uses point-based rendering techniques to visualize the point cloud. Our direct isosurface extraction algorithm for scattered volume data produces results of quality close to the results from standard isosurface extraction algorithms for gridded volume data (like marching cubes). In comparison to 3D mesh generation algorithms (like Delaunay tetrahedrization), our algorithm is about one order of magnitude faster for the examples used in this paper.

Betreuung: Dorit Merhof

 

Thema: Multi-level partition of implicits
(Siggraph 2003)

URL: http://www.mpi-inf.mpg.de/~ohtake/mpu_implicits/

Abstract: We present a shape representation, the multi-level partition of unity implicit surface, that allows us to construct surface models from very large sets of points. There are three key ingredients to our approach: 1) piecewise quadratic functions that capture the local shape of the surface, 2) weighting functions (the partitions of unity) that blend together these local shape functions, and 3) an octree subdivision method that adapts to variations in the complexity of the local shape. Our approach gives us considerable flexibility in the choice of local shape functions, and in particular we can accurately represent sharp features such as edges and corners by selecting appropriate shape functions.

Betreuung: Jochen Süßmuth

Thema: Image based material editing
(Siggraph 2006)

URL: http://graphics.cs.ucf.edu/ekhan/project_ibme.htm

Abstract: Photo editing software allows digital images to be blurred, warped or re-colored at the touch of a button. However, it is not currently
possible to change the material appearance of an object except by painstakingly painting over the appropriate pixels. Here we present
a method for automatically replacing one material with another, completely different material, starting with only a single high dynamic
range image as input. Our approach exploits the fact that human vision is surprisingly tolerant of certain (sometimes enormous)
physical inaccuracies, while being sensitive to others. By adjusting our simulations to be careful about those aspects to which
the human visual system is sensitive, we are for the first time able to demonstrate significant material changes on the basis of a single
photograph as input.

Betreuung: Frank Bauer

Thema: Fast Separation of Direct and Global Images
(Siggraph 2006)

URL: http://www1.cs.columbia.edu/CAVE/projects/separation/separation.php

Abstract: We present fast methods for separating the direct and global illuminationcomponents of a scene measured by a camera and illuminated by a light source. In theory, the separation can be done with just two images taken with a high frequency binary illumination pattern and its complement. In practice, a larger number of images are used to overcome the optical and resolution limitations of the camera and the source. The approach does not require the material properties of objects and media in the scene to be known. However, we require that the illumination frequency is high enough to adequately sample the global components received by scene points. We present separation results for scenes that include complex interreflections, subsurface scattering and volumetric scattering. Several variants of the separation approach are also described. When a sinusoidal illumination pattern is used with different phase shifts, the separation can be done using just three images. When the computed images are of lower resolution than the source and the camera, smoothness constraints are used to perform the separation using a single image. Finally, in the case of a static scene that is lit by a simple point source, such as the sun, a moving occluder and a video camera can be used to do the separation. We also show several simple examples of how novel images of a scene can be computed from the separation results.

Betreuung: Martin Meister

Thema: Interpolating Implicit Surfaces from Scattered Surface Data Using Compactly Supported Radial Basis Functions
(Siggraph 2005)

URL: http://www.cs.stevens.edu/~quynh/courses/cs638-sp05/morse_yoo_implicit.pdf

Abstract: We describe algebraic methods for creating implicit surfaces using linear combinations of radial basis interpolants to form complex models from scattered surface points. Shapes with arbitrary topology are easily represented without the usual interpolation or aliasing errors arising from discrete sampling. These methods were first applied to implicit surfaces by Savchenko, et al. and later developed independently by Turk and O'Brien as a means of performing shape interpolation. Earlier approaches were limited as a modeling mechanism because of the order of the computational complexity involved. We explore and extend these implicit interpolating methods to make them suitable for systems of large numbers of scattered surface points by using compactly supported radial basis interpolants. The use of compactly supported elements generates a sparse solution space, reducing the computational complexity and making the technique practical for large models. The local nature of compactly supported radial basis functions permits the use of computational techniques and data structures such as k-d trees for spatial subdivision, promoting fast solvers and methods to divide and conquer many of the subproblems associated with these methods. Moreover, the representation of complex models permits the exploration of diverse surface geometry. This reduction in computational complexity enables the application of these methods to the study of shape properties of large complex shapes.

Betreuung: Marco Winter