Tobias Schafhitzel

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Modern medical imaging provides a variety of techniques for the acquisition of multi-modality data. A typical example is the combination of functional and anatomical data from functional Magnetic Resonance Imaging (fMRI) and anatomical MRI measurements. Usually, the data resulting from each of these two methods is transformed to 3D scalar-field(More)
We introduce a point-based algorithm for computing and rendering stream surfaces and path surfaces of a 3D flow. The points are generated by particle tracing, and an even distribution of those particles on the surfaces is achieved by selective particle removal and creation. Texture-based surface flow visualization is added to show inner flow structure on(More)
In this paper, we present a mapping of nonlinear ray tracing to the GPU which avoids any data transfer back to main memory. The rendering process consists of the following parts: ray setup according to the camera parameters , ray integration, ray–object intersection, and local illumination. Bent rays are approximated by polygonal lines that are represented(More)
This paper presents an interactive technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a 3D graphics processing unit (GPU)-based texture advection mechanism that implements logical 3D grid structures by physical memory in the(More)
We present a framework for interactively visualizing volumetric Adaptive Mesh Refinement (AMR) data. For this purpose we employ complex data structures to map the entire AMR dataset to graphics memory. This allows to apply hardware accelerated visualization algorithms previously only operating on uniform cartesian grids. For mapping the data to graphics(More)
This paper presents an interactive technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a novel 3D GPU-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures.(More)
We propose a novel vortex core line extraction method based on the λ 2 vortex region criterion in order to improve the detection of vortex features for 3D flow visualization. The core line is defined as a curve that connects λ 2 minima restricted to planes that are perpendicular to the core line. The basic algorithm consists of the following stages: (1) λ 2(More)
This paper presents a real time technique for planetary rendering and atmospheric scattering effects. Our implementation is based on Nishita's atmospheric model which describes actual physical phenomena, taking into account air molecules and aerosols, and on a continuous level-of-detail planetary renderer. We obtain interactive frame rates by combining the(More)
This paper describes methods for explanatory and illustrative visualizations used to communicate aspects of Einstein's theories of special and general relativity, their geometric structure, and of the related fields of cosmology and astrophysics. Our illustrations target a general audience of laypersons interested in relativity. We discuss visualization(More)
Flow visualization is a classic sub-field of scientific visualization. The task of flow visualization algorithms is to depict vector data, i.e., data with magnitude and direction. An important category of flow visualization techniques makes use of textures in order to convey the properties of a vector field. Recently, several research advances have been(More)