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In this paper we present a new concept of transfer functions for direct volume rendering. In contrast to previous work, we attempt to define a transfer function in the domain of principal curvature magnitudes. Such a definition helps the user to suppress or enhance structures of a specific shape class. It also allows to set a smooth color or opacity(More)
In this paper we present a fast visualization technique for volumetric data, which is based on a recent non-photorealistic rendering technique. Our new approach enables alternative insights into 3D data-sets (compared to traditional approaches such as direct volume rendering or iso-surface rendering). Object contours, which usually are characterized by(More)
Simulation and visualization of NC milling processes has become an important step in computer aided manufacturing. The usage of stock materials with specific locally varying properties (like density, accuracy, color,.. .) becomes more and more important with new technologies emerging in the material industry. Our new approach, using volumet-ric(More)
Maximum Intensity Projection (MIP) is a volume rendering technique which is used to extract high-intensity structures from volumetric scalar data. At each pixel the highest data value encountered along the corresponding viewing ray is determined. MIP is commonly used to extract vascular structures from medical MRI data sets, i.e., angiography. The usual way(More)
A new user-interface paradigm for the specification of transfer functions is presented. The specification is usually a difficult task as mapping information for a number of different domains (data range, color, opacity, etc.) has to be defined. In the presented approach, the definition of the mapping information can be realized independently for each(More)
The majority of virtual endoscopy techniques tries to simulate a real endoscopy. A real endoscopy does not always give the optimal information due to the physical limitations it is subject to. In this paper, we deal with the unfolding of the surface of the colon as a possible visualization technique for diagnosis and polyp detection. A new two-step(More)
In this paper a new gradient estimation method is presented which is based on linear regression. Previous con-textual shading techniques try to fit an approximate function to a set of surface points in the neighborhood of a given voxel. Therefore a system of linear equations has to be solved using the computationally expensive Gaussian elimination. In(More)
a) b) c) Figure 1: Surface of the segmented organ together with the cylindrical approximation: a) CT colon data. b) The same CT colon data as in a but using a different wall thickness. c) CT kidney data set. The segmented organ is the aorta. Abstract Virtual endoscopy is a promising medical application of volume vi-sualization techniques. A virtual(More)