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Arrange Spatial Data
Published in Tamara Munzner, Visualization Analysis and Design, 2014
The direct volume rendering idiom creates an image directly from the information contained within the scalar spatial field, without deriving an intermediate geometric representation of a surface. The algorithmic issues involved in the computation are complex; a great deal of work has been devoted to the question of how to carry it out efficiently and correctly.
Volume Visualization
Published in Alexandru Telea, Data Visualization, 2014
The basic idea behind volume rendering is simple: create a two-dimensional image that reflects, at every pixel, the scalar data within a given 3D dataset along a ray parallel to the viewing direction passing through that pixel. The main power of volume visualization is in the choice of the function that maps an entire set of scalar values, corresponding to the voxels along such a ray, to a single pixel in the resulting 2D image. Appropriate choices for this function let us convey a wide range of insights into volumetric scalar datasets.
Methods for Analyzing Floc Properties
Published in Ian G. Droppo, Gary G. Leppard, Steven N. Liss, Timothy G. Milligan, FLOCCULATION in NATURAL and ENGINEERED ENVIRONMENTAL SYSTEMS, 2004
Ian G. Droppo, Gary G. Leppard, Steven N. Liss, Timothy G. Milligan
Functions for lighting and shading can significantly improve the 3D impression of the rendered images. The quality and information content of 3D visualization is strongly influenced by the applied rendering algorithm. The surfaces of objects can be mathematically transformed to 3D meshes of polygons. 67 The polygons are projected to 2D space, are drawn by the program in a color defined by the user, and are shaded according to the directions of their surface normal vectors and according to the position of a virtual light source. Algorithms based on this approach are relatively simple and fast because only the vertices and the surface normal vectors of the polygons are stored and processed. In contrast, volume rendering uses the whole content of an image stack (the empty space as well as the surfaces and the inner parts of objects) for 3D visualization. Such programs can produce very detailed 3D reconstructions, but interactive volume rendering requires fast computers and sophisticated software implementations. The increasing performance of commodity computers makes 3D visualization by volume rendering cheaper and easier to use as a routine tool in floc and biofilm research.
Evaluating surface visualization methods in semi-transparent volume rendering in virtual reality
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2021
Gloria Zörnack, Jakob Weiss, Georg Schummers, Ulrich Eck, Nassir Navab
Volume rendering has become a ubiquitous way for visualising 3D and 4D volumetric data, predominantly used for scientific and medical data sets. GPU-accelerated Direct Volume Rendering (DVR) as described in Krüger and Westermann (2004) is a way to leverage the high parallel computing power of the GPU to render volumetric data without extracting mesh geometry and enables real-time volume rendering at high framerates. This enables the use of DVR in immersive Virtual Reality (VR), a technology that has seen rising interest in the medical community. Combining mesh geometry with DVR has obvious uses in volumetric image analysis applications: showing indicators such as arrows, cursors or location markers as user interface element within the volume to highlight or annotate positions is a common feature. In VR, integrating the visual representation of a handheld controller is an important cue to support natural user interaction: The user’s ”hand” should be able to enter the DVR volume without visual artefacts. Rendering the additional geometry semi-transparently can help retain visibility of the relevant volumetric information.
Shape Reconstruction of Columnar Structure Defect
Published in Research in Nondestructive Evaluation, 2022
Gangfeng Zheng, Hao Dong, Ze Li, Songfeng Liu, Bin Wu, Cunfu He
The medical volume rendering method is a visualization of 3D volume data. Volume rendering means processing the scalar field information in 3D volume data, calculating the approximate volume rendering integrals for each pixel, and acquiring the corresponding reconstructed image after assigning the corresponding color, opaqueness, and illumination information [10]. Reconstruction was realized using the light ray projection method in volume rendering, namely, reconstructing the 2D projected image, which was obtained through the action of light ray, through voxels.
Isosurface rendering of medical images improved by automatic texture mapping
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2018
Thiago F. de Moraes, Paulo H. J. Amorim, Jorge V. L. da Silva, Helio Pedrini
Direct volume rendering approaches (Drebin et al. 1988; Levoy 1990) map each voxel value to color and opacity attributes through a transfer function, whose result is projected on the corresponding frame buffer pixel. Among the different mapping strategies for direct volume rendering, the most widely used are volume ray casting (Roth 1982), splatting (Westover 1989), shell rendering (Udupa & Odhner 1993), and shear warp (Lacroute & Levoy 1994).