Efficient Surface Reconstruction for Piecewise Smooth Objects

In this report we present a new surface reconstruction technique from unstructured point clouds for piecewise smooth objects, such as scans of architectural and other man-made artifacts. The new technique operates in three conceptual steps: First, a set of basis functions is computed and a topology is established among these functions that respect sharp features using a RANSAC technique. Second, a linearized, statistically motivated optimization problem is solved employing this discretization. Lastly, an implicit function based meshing technique is employed to determine a clean, manifold mesh representation. The main benefit of our new proposal in comparison to previous work is its robustness and efficiency, which we examine by applying the algorithm to a set of synthetic and real-world benchmark data sets

A consistent bending model for cloth simulation with corotational subdivision finite elements

Modelling bending energy in a consistent way is decisive for the realistic simulation of cloth. With existing approaches characteristic behaviour like folding and buckling cannot be reproduced in a physically convincing way. We present a new method based on a corotational formulation of subdivision finite elements. Due to the non-local nature of the employed subdivision basis functions a C1-continuous displacement field can be defined. It is thus possible to use the governing equations of thin shell analysis leading to a physically accurate bending behaviour. Using a corotated strain tensor allows the large displacement analysis of cloth while retaining a linear system of equations. Hence, known convergence properties and computational efficiency are preserved

Reality Tooning: Fast Non-Photorealism for Augmented Video Streams (poster

Recently, we have proposed a novel approach to generating augmented video streams. The output images are a non-photorealistic reproduction of the augmented environment. Special stylization methods are applied to both the background camera image and the virtual objects. This way, the graphical foreground and the real background images are rendered in a similar style, so that they are less distinguishable from each other. Here, we present a new algorithm for the cartoon-like stylization of augmented reality images, which uses a novel post-processing filter for cartoon-like color segmentation and high-contrast silhouettes. In order to make a fast post-processing of rendered images possible, the programmability of modern graphics hardware is exploited. The system is capable of generatin

A Finite Element Method for Interactive Physically Based Shape Modelling with Quadratic Tetrahedra

We present an alternative approach to standard geometric shape editing using physically-based simulation. With our technique, the user can deform complex objects in real-time. The enabling technology of this approach is a fast and accurate finite element implementation of an elasto-plastic material model, specifically designed for interactive shape manipulation. Using quadratic shape functions, we avoid the inherent drawback of volume locking exhibited by methods based on linear finite elements. The physical simulation uses a tetrahedral mesh, which is constructed from a coarser approximation of the detailed surface. Having computed a deformed state of the tetrahedral mesh, the deformation is transferred back to the high detail surface. This can be accomplished in an accurate and efficient way using the quadratic shape functions. In order to guarantee stability and real-time frame rates during the simulation, we cast the elasto-plastic problem into a linear formulation. For this purpose, we present a corotational formulation for quadratic finite elements. We demonstrate the versatility of our approach in interactive manipulation sessions and show that our animation system can be coupled with further physics-based animations like, e.g. fluids and cloth, in a bi-directional way

Sparse Registration - 3D Reconstruction from Pairs of 2D Line Scans

We address a new registration problem: Using a coupled pair of 2d scanners, we capture range data by freely moving the system through the scene. The registration with regard to six degrees of freedom becomes solvable due to the fact that rst, the pair of line scanners has dierent orientation, and second, we use a volume-oriented algorithm instead of commonly used surface-oriented approaches. We present a method that is based on the idea of preserving the free space represented in each of the scans. The proposed algorithm is evaluated with real range data associated with orientation estimates from an inertia sensor. Additionally, we provide quantitative results with simulated data. In both cases, the algorithm is capable to recover from large translational and moderate rotational errors in the initial conguration

Three architectures for volume rendering

Volume rendering is a key technique in scientific visualization that lends itself to significant exploitable parallelism. The high computational demands of real-time volume rendering and continued technological advances in the area of VLSI give impetus to the development of special-purpose volume rendering architectures. This paper presents and characterizes three recently developed volume rendering engines which are based on the ray-casting method. A taxonomy of the algorithmic variants of ray-casting and details of each ray-casting architecture are discussed. The paper then compares the machine features and provides an outlook on future developments in the area of volume rendering hardware

Efficient multiple occlusion queries for scene graph systems

Image space occlusion culling is an useful approach to reduce the rendering load of large polygonal models. Like most large model techniques, it trades overhead costs with the rendering costs of the possibly occluded geometry. Meanwhile, modern graphics hardware supports occlusion culling. Unfortunately these hardware extensions consume fillrate and latency costs. In this paper, we propose a new technique for scene graph traversal optimized for efficient use of occlusion queries. Our approach uses several Occupancy Maps to organize the scene graph traversal. During traversal hierarchical occlusion culling, view frustrum culling and rendering is performed. The occlusion information is efficiently determined by asynchronous multiple occlusion queries with hardware-supported query functionality. To avoid redundant results, we arrange these multiple occlusion queries according to the information of several Occupancy Maps. Our presented technique is conservative and benefits from a partial depth order of the geometry

A Real-Time Sound Rendering Algorithm for Complex Scenes

We present a novel output-sensitive algorithm for sound rendering of complex scenes, i.e. scenes that contain a large amount of sound sources