VG03: Third International Workshop on Volume Graphics 2003

Permanent URI for this collection

https://diglib7.eg.org/handle/10.2312/473

Browse

Now showing 1 - 17 of 17

The Design and Evaluation of a Pipelined Image Compositing Device for Massively Parallel Volume Rendering
(The Eurographics Association, 2003) Ogata1, Masato; Muraki, Shigeru; Liu, Xuezhen; Ma, Kwan-Liu; I. Fujishiro and K. Mueller and A. Kaufman
An experimental study of software image compositing that we have carried out on a 512-node PC cluster shows the necessity of hardware compositing support to make possible real-time volume visualization scalable with large PC clusters. This paper describes the design and performance evaluation of such a hardware image compositing device. A PC cluster using such devices along with commodity graphics cards can enable simultaneous simulation and volume visualization.
Multiresolution Volume Simplification and Polygonization
(The Eurographics Association, 2003) Zhang, Nan; Kaufman, Arie; I. Fujishiro and K. Mueller and A. Kaufman
We propose a multiresolution volume simplification and polygonization algorithm. Traditionally, voxel-based algorithms lack the adaptive resolution support and consequently simplified volumes quickly lose sharp features after several levels of downsampling, while tetrahedral-based simplification algorithms usually generate poorly shaped triangles. In our method, each boundary cell is represented by a carefully selected representative vertex. The quadric error metrics are applied as the geometric error metric. Our approach first builds an error pyramid by bottom-up cell merging. We avoid topology problems in hierarchical cell merging by disabling erroneous cells and penalizing cells containing disconnected surface components with additional costs. Then, a top-down traversal is used to collect cells within a user specified error threshold. The surfacenets algorithm is used to polygonize these cells. We enhance it with online triangle shape optimization and budget control. Finally, we discuss a novel octree implementation which greatly eases the polygonization operations.
OpenVL - The Open Volume Library
(The Eurographics Association, 2003) Lakare, Sarang; Kaufman, Arie; I. Fujishiro and K. Mueller and A. Kaufman
OpenVL is a modular, extensible, and high performance library for handling volumetric datasets. It provides a standard, uniform, and easy to use API for accessing volumetric data. It allows the volumetric data to be laid out in different ways to optimize memory usage and speed. It supports reading/writing of volumetric data from/to files in different formats using plugins. It provides a framework for implementing various algorithms as plugins that can be easily incorporated into user applications. The plugins are implemented as shared libraries which can be dynamically loaded as needed. OpenVL is developed openly and is a free software available on the web.
Rapid Emission Tomography Reconstruction
(The Eurographics Association, 2003) Chidlow, Ken; Möller, Torsten; I. Fujishiro and K. Mueller and A. Kaufman
We present new implementations of the Maximum Likelihood Expectation Maximization (EM) algorithm and the related Ordered Subset EM (OSEM) algorithm. Our implementation is based on modern graphics hardware and achieves speedups of over eight times current software implementation, while reducing the RAM required to practical amounts for today's PC's. This is significant as it will make this algorithm practical for clinical use. In order to achieve a large speed up, we present bit splitting over different color channels as an accumulation strategy. We also present a novel hardware implementation for volume rendering emission data without loss of accuracy. Improved results are achieved through incorporation of attenuation correction with only a small speed penalty.
Chronovolumes: A Direct Rendering Technique for Visualizing Time-Varying Data
(The Eurographics Association, 2003) Woodring, Jonathan; Shen, Han-Wei; I. Fujishiro and K. Mueller and A. Kaufman
We present a new method for displaying time varying volumetric data. The core of the algorithm is an integration through time producing a single view volume that captures the essence of multiple time steps in a sequence. The resulting view volume then can be viewed with traditional raycasting techniques. With different time integration functions, we can generate several kinds of resulting chronovolumes, which illustrate differing types of time varying features to the user. By utilizing graphics hardware and texture memory, the integration through time can be sped up, allowing the user interactive control over the temporal transfer function and exploration of the data.
Volume CAD
(The Eurographics Association, 2003) Kase, K.; Teshima, Y.; Usami, S.; Ohmori, H.; Teodosiu, C.; Makinouchi, A.; I. Fujishiro and K. Mueller and A. Kaufman
With the transition of the most fundamental data in manufacturing from drawings to three-dimensional (3D) CAD (Computer Aided Design) data, we are now able to fabricate products with beautiful curved surfaces, for example, automobiles, cellular phones, etc. However, current 3D CAD involves only shape data, which consequently poses certain difficulties in process modeling and simulations aimed at predicting the performance of final products. This paper introduces the Volume CAD (V-CAD) Project and the development of the first (voxel) version of V-CAD, which is capable of storing relevant 3D physical attributes as well as shape data. The data structure, volumization process from surface information, and "coloring" in 3D space are proposed. V-CAD allows sharing of robust data with decisive accuracy by various simulations and flexible manufacturing methods.
Cell Projection of Convex Polyhedra
(The Eurographics Association, 2003) Roettger, Stefan; Ertl, Thomas; I. Fujishiro and K. Mueller and A. Kaufman
Finite element methods commonly use unstructured grids as the computational domain. As a matter of fact, the volume visualization of these unstructured grids is a time consuming task. Here, the fastest known object order algorithm is the projected tetrahedra algorithm of Shirley and Tuchman. Even with the upcoming of programmable graphics hardware, the rendering performance did not keep up with the growing complexity of the simulation data. In this paper we strive to improve the performance of the cell projection technique by posing several restrictions on the optical model. This allows us to devise a simple but fast hardware-accelerated algorithm which is able to project arbitrary polyhedral cells, that is tetrahedra, prisms, hexahedra, etc. For this reason, our algorithm is well suited for the display of unstructured FEM meshes with mixed cell types, but it is also applicable to the real-time display of gaseous phenonema, such as fire and ground fog.
Volumetric Ablation Rendering
(The Eurographics Association, 2003) Varadhan, Hari; Mueller, Klaus; I. Fujishiro and K. Mueller and A. Kaufman
In this paper, we propose a physically-based method for simulating the process of ablation on volumetric models. We demonstrate the visual effect of ablative processes, such as a beam of heat emitted from a blow torch or a pencil of sand expelled from a sandblaster. Users are able to control ablative properties, such as energy propagation, absorption, and material evaporation, via a simple transfer function interface, while the effect of different beam shapes can be modeled by ways of weighting functions. Continuous evaporation of material to expose interior object features can eliminate smooth object boundary layers required for good gradient estimation. To prevent this adverse effect, our method leaves the original volume intact and instead operates on a smooth energy volume. The renderer then uses the energy volume to determine the current, smooth object boundaries, for the opacity and gradient calculations, while the original volume provides the visual material properties, such as color and shading coefficients.
Real-Time Volume Manipulation
(The Eurographics Association, 2003) Singh, V.; Silver, D.; Cornea, N.; I. Fujishiro and K. Mueller and A. Kaufman
In this paper, we describe a set of algorithms and an implementation (called VolEdit), for interactively manipulating 3D volumetric objects (datasets). The system utilizes skeletons, which allows users/animators to interactively and intuitively specify the location and type of deformation desired. The skeleton is extracted automatically from the volumetric model and indexes the appropriate part of the volume that needs to be transformed by defining piecewise bounds of the volume. The deformed volume is then reconstructed and rendered using commodity graphics cards. The system performs in real-time with near-interactive speeds. The VolEdit system is demonstrated with two volumes, the Visible Human Dataset and a colon MRI dataset.
Hybrid Forward Resampling and Volume Rendering
(The Eurographics Association, 2003) Yuan, Xiaoru; Nguyen, Minh X.; Xu, Hui; Chen, Baoquan; I. Fujishiro and K. Mueller and A. Kaufman
The transforming and rendering of discrete objects, such as traditional images (with or without depths) and volumes, can be considered as resampling problem - objects are reconstructed, transformed, filtered, and finally sampled on the screen grids. In resampling practices, discrete samples (pixels, voxels) can be considered either as infinitesimal sample points (simply called points) or samples of a certain size (splats). Resampling can also be done either forwards or backwards in either the source domain or the target domain. In this paper, we present a framework that features hybrid forward resampling for discrete rendering. Specifically, we apply this framework to enhance volumetric splatting. In this approach, minified voxels are taken simply as points filtered in screen space; while magnified voxels are taken as spherical splats. In addition, we develop two techniques for performing accurate and efficient perspective splatting. The first one is to efficiently compute the 2D elliptical geometry of perspectively projected splats; the second one is to achieve accurate perspective reconstruction filter. The results of our experiments demonstrate both the effectiveness of antialiasing and the efficiency of rendering using this approach.
Spatial Transfer Functions - A Unified Approach to Specifying Deformation in Volume Modeling and Animation
(The Eurographics Association, 2003) Chen, M.; Silvery, D.; Winter, A. S.; Singhy, V.; Cornea, N.; I. Fujishiro and K. Mueller and A. Kaufman
In this paper, we introduce the concept of spatial transfer functions as a unified approach to volume modeling and animation. A spatial transfer function is a function that defines the geometrical transformation of a scalar field in space, and is a generalization and abstraction of a variety of deformation methods. It facilitates a fieldbased representation, and can thus be embedded into a volumetric scene graph under the algebraic framework of constructive volume geometry. We show that when spatial transfer functions are treated as spatial objects, constructive operations and conventional transfer functions can be applied to such spatial objects.We demonstrate spatial transfer functions in action with the aid of a collection of examples in volume visualization, sweeping, deformation and animation. In association with these examples, we describe methods for modeling and realizing spatial transfer functions, including simple procedural functions, operational decomposition of complex functions, large scale domain decomposition and temporal spatial transfer functions. We also discuss the implementation of spatial transfer functions in the vlib API and our efforts in deploying the technique in volume animation.
Integrating Pre-Integration Into The Shear-Warp Algorithm
(The Eurographics Association, 2003) Schulze, J.P.; Kraus, M.; Lang, U.; Ertl, T.; I. Fujishiro and K. Mueller and A. Kaufman
The shear-warp volume rendering algorithm is one of the fastest algorithms for volume rendering, but it achieves this rendering speed only by sacrificing interpolation between the slices of the volume data. Unfortunately, this restriction to bilinear interpolation within the slices severely compromises the resulting image quality. This paper presents the implementation of pre-integrated volume rendering in the shear-warp algorithm for parallel projection to overcome this drawback. A pre-integrated lookup table is used during compositing to perform a substantially improved interpolation between the voxels in two adjacent slices. We discuss the design and implementation of our extension of the shear-warp algorithm in detail. We also clarify the concept of opacity and color correction, and derive the required sampling rate of volume rendering with postclassi fication. Furthermore, the modified algorithm is compared to the traditional shear-warp rendering approach in terms of rendering speed and image quality.
A Volume Rendering Approach for Sea Surfaces Taking into Account Second Order Scattering Using Scattering Maps
(The Eurographics Association, 2003) Iwasaki, Kei; Dobashi, Yoshinori; Nishita, Tomoyuki; I. Fujishiro and K. Mueller and A. Kaufman
We present a fast volume rendering technique for sea surfaces taking into account second order scattering using graphics hardware. To generate realistic images of the sea surfaces, accurate simulation of light transport within water is necessary. In particular, multiple scattering due to particles in the water plays an important role in creating realistic images. In this paper, we introduce the concept of a scattering map for efficient computation of light scattering within water volume. In order to calculate second order scattering of light, we slice the water volume into virtual horizontal planes and calculate the radiance from second order scattering of light at sampling points on these planes. The radiance on the virtual planes can be treated as a texture map. This makes it possible to accelerate the computation using graphics hardware.
An Interactive Volume Visualization System for Transient Flow Analysis
(The Eurographics Association, 2003) Rosa, Gabriel G.; Lum, Eric B.; Ma, Kwan-Liu; Ono, Kenji; I. Fujishiro and K. Mueller and A. Kaufman
This paper describes the design and performance of an interactive visualization system developed specifically for improved understanding of time-varying volume data from thermal flow simulations for vehicle cabin and ventilation design. The system uses compression to allows for better memory utilization and faster data transfer, hardware accelerated rendering to enable interactive exploration, and an intuitive user interface to support comparative visualization. In particular, the interactive exploration capability offered by the system raises scientists to a new level of insight and comprehension. Compared to a previous visualization solution, such a system helps scientists more quickly identify and correct design problems.
Remote View-dependent Isosurface Visualization
(The Eurographics Association, 2003) Liu, Zhiyan; Li, Kai; I. Fujishiro and K. Mueller and A. Kaufman
This paper presents a simple and effective protocol for remote isosurface visualization. The protocol breaks up the isosurface visualization pipeline at the 3D primitive stage for the server to send primitives to the client. Several techniques are used in the protocol to reduce communication requirement and to provide interactive visualization. The server runs an efficient isosurface extraction algorithm that generates view-dependent portions of the isosurface. The resulting 3D primitives are organized into groups and sent to the client to be rendered. Our approach uses primitive compression, progressive level-ofdetail, and primitive caching techniques to improve the interactivity perceived by the user. This paper reports and compares the experiment results under different settings to show the effectiveness of these techniques. Applied together, they reduce both the amount of data transferred and time spent when the result becomes 90% correct by two orders of magnitude.
Out-of-Core Encoding Of Large Tetrahedral Meshes
(The Eurographics Association, 2003) Ueng, Shyh-Kuang; I. Fujishiro and K. Mueller and A. Kaufman
In this paper, an out-of-core data compression method is presented to encode large Finite Element Analysis (FEA) meshes. The method is comprised with two stages. At the first stage, the input FEA mesh is divided into blocks, called octants, based on an octree structure. Each octant must contain less FEA cells than a predefined limit such that it can fit into the main memory. Octants produced in the data division are stored in disk files. At the second stage, the octree is traversed to enumerate all the octants. These octants are fetched into the main memory and compressed there one by one. To compress an octant, the cell connectivities of the octant are computed. The connectivities are represented by using an adjacency graph. In the graph, a graph vertex represents an FEA cell, and if two cells are adjacent by sharing a face then an edge is drawn between the corresponding vertices of the cells. Next the adjacency graph is traversed by using a depth first search, and the mesh is split into tetrahedral strips. In a tetrahedral strip, every two consecutive cells share a face, and only one vertex reference is needed for specifying a cell. Therefore, less memory space is required for storing the mesh. According to the different situations encountered during the depth first search, the tetrahedral strips are encoded by using four types of instructions. When the traversal is completed, the tetrahedral strips are converted into a byte string and written into a disk file. To decode the compressed mesh, the instructions kept in the disk file are fetched into the main memory in blocks. For each block of instructions, the instructions are executed one by one to reconstruct the mesh. Test results reveal that the out-of-core compression method can compress large meshes on a desk-top machine with moderate memory space within reasonable time. The out-of-core method also achieves better compression ratios than an incore method which was developed in a previous research.
Accuracy-Based Sampling and Reconstruction with Adaptive Grid for Parallel Hierarchical Tetrahedrization
(The Eurographics Association, 2003) T.Tanaka, Hiromi; Takama, Yasufumi; Wakabayashi, Hiroki; I. Fujishiro and K. Mueller and A. Kaufman
Recent advances in volume scanning techniques have made the task of acquiring volume data of 3-D objects easier and more accurate. Since the quantity of such acquired data is generally very large, a volume model capable of compressing data while maintaining a specified accuracy is required. The objective of this work is to construct a multi resolution tetrahedra representation of input volume data. This representation adapts to local field properties while preserving their discontinuities. In this paper, we present an accuracy-based adaptive sampling and reconstruction technique, we call an adaptive grid, for hierarchical tetrahedrization of C1 continuous volume data. We have developed a parallel algorithm of adaptive grid generation that recursively bisects tetrahedra gird elements by increasing the number of grid nodes, according to local field properties and such as orientation and curvature of isosurfaces, until the entire volume has been approximated within a specified level of view-invariant accuracy. We have also developed a parallel algorithm that detects and preserves bothC0 andC1 discontinuities of field values, without the formation of cracks which normally occur during independent subdivision. Experimental results demonstrate the validity and effusiveness of the proposed approach.

Browse

Browsing VG03: Third International Workshop on Volume Graphics 2003 by Issue Date

Results Per Page

Sort Options