Showing papers in "IEEE Computer Graphics and Applications in 1991"
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TL;DR: The important characteristics of NURBS that have contributed to their wide acceptance as standard tools for geometry representation and design are summarized and their application to representing conic sections and commonly used surfaces, designing curves and surfaces, and modifying shapes is examined.
Abstract: Nonuniform rational B-spline (NURBS) curves and surfaces, which are based on rational and B-splines, are defined. The important characteristics of NURBS that have contributed to their wide acceptance as standard tools for geometry representation and design are summarized. Their application to representing conic sections and commonly used surfaces, designing curves and surfaces, and modifying shapes is examined. >
797Â citations
TL;DR: Methods for automating the analysis and display of vector fieldTopology in general, and flow topology in particular, are described, finding that by using techniques to extract and visualize topological information, it is possible to combine the simplicity of schematic depictions with the quantitative accuracy of curves and surfaces computed directly from the data.
Abstract: Methods for automating the analysis and display of vector field topology in general, and flow topology in particular, are described. By using techniques to extract and visualize topological information, it is possible to combine the simplicity of schematic depictions with the quantitative accuracy of curves and surfaces computed directly from the data. Two-dimensional vector field topology is discussed, covering critical points and time-dependent flows, to provide a basis for the examination of topology in three-dimensional separated flows. Surface topology and separation structures in three-dimensional flows are then addressed. The construction of representations of tangent surfaces that are accurate, as well as efficient to compute and display, is examined, covering tessellation, clipping, and refinement. Locating, characterizing, and displaying three-dimensional critical points are considered. >
523Â citations
TL;DR: In this paper, a Morse-based coding system for representing the hierarchical structure of contours is presented, and the resulting coding works interactively with a range of surface reconstruction systems.
Abstract: Coding system requirements are briefly discussed. Classical Morse theory, which was primarily motivated by the calculus of variations, is reviewed. The limits of the theory are examined, and an extension that enables 3-D surfaces to be accurately reconstructed from cross sections is presented. The resulting coding works interactively with a range of surface reconstruction systems. The prototype coding system is applied to representing the hierarchical structure of contours. >
372Â citations
TL;DR: A fundamentally new type of CAD system for designing shape that is intuitive, easy to use, and powerful is presented, based on a paradigm that can be described as designing directly in 3-D.
Abstract: A fundamentally new type of CAD system for designing shape that is intuitive, easy to use, and powerful is presented. It is based on a paradigm that can be described as designing directly in 3-D. By virtue of two hand-held sensors, designers using 3-Draw to sketch their ideas in the air feel as if they're actually holding and working on objects. Current design practice and related work are reviewed, and current work on 3-Draw is summarized. To capture the flavor of 3-Draw, construction of a sample model of a 12-m yacht is described. 3-Draw's features and data structures are discussed. >
298Â citations
TL;DR: The development of robust frameworks in interactive multimedia for representing story elements to the machine so that they can be retrieved in multiple contexts is addressed and it is proposed that content can be represented in layers.
Abstract: The development of robust frameworks in interactive multimedia for representing story elements to the machine so that they can be retrieved in multiple contexts is addressed. Interactive multimedia is discussed as a user-directed form of storytelling, and the nature of cinematic storytelling is examined. It is proposed that content can be represented in layers. This model for layered information will allow programs to take advantage of the relation between cinematic sequences and the world they represent. The collection of content by the camera and microphone is considered in this context. The use of the methodology to build meaningful, context-rich sequences is discussed. >
275Â citations
TL;DR: The Reeb graph represents the topological skeleton of a 3-D object and shows between which contours the surface patches should be generated and is completed by adding edges that do not contradict the known number of holes in descending order of the weight.
Abstract: The Reeb graph represents the topological skeleton of a 3-D object and shows between which contours the surface patches should be generated. To construct the graph automatically, a weight function is defined for a pair of contours with each contour lying on the adjacent cross sections. First, the algorithm automatically generates the major parts of the edges of the Reeb graph where the number of contours does not change. Then the rest of the graph is determined by using the weight function and prior knowledge of the number of holes the object has. Specifically, the graph is completed by adding edges that do not contradict the known number of holes in descending order of the weight. >
213Â citations
TL;DR: The model of spinal motion, which is represented within Jack (a software system for human figure modeling and manipulation), is described and the impact parameters, vertebral joint movement, and the spine database are considered.
Abstract: Efforts to develop a more accurate model of the human spine and torso in order to improve realism in human motion modeling are discussed. The model of spinal motion, which is represented within Jack (a software system for human figure modeling and manipulation), is described. The impact parameters, vertebral joint movement, and the spine database are considered. Application of the motion model is examined, and examples of its use are given. >
137Â citations
TL;DR: The main goal of the authors is to improve on commercial SPECT reconstruction algorithms and provide quantification accuracy sufficient for numerical assessment of tracer distribution.
Abstract: Software that has been developed to automate and standardize comparison of 3D images is discussed. The major approaches to image registration are examined. The authors' registration and reconstruction software is described. Studies carried out to determine the relative accuracy of the present registration methods are reported. The main goal of the authors is to improve on commercial SPECT reconstruction algorithms and provide quantification accuracy sufficient for numerical assessment of tracer distribution. >
133Â citations
TL;DR: A set of algorithms for interactive visualization, manipulation, and measurement of large 3-D objects on general-purpose workstations is described, based on a method of representing digital structures called a semiboundary.
Abstract: A set of algorithms for interactive visualization, manipulation, and measurement of large 3-D objects on general-purpose workstations is described. They are based on a method of representing digital structures called a semiboundary. This data structure stores boundary and interior information. The use of these algorithms for visualizing medical data is addressed. Examples of their use are given. >
116Â citations
TL;DR: A classification of models for animating synthetic actors is proposed based on the motion control method used and the type of actor interaction and these interactions give rise to a classification array with four rows and three columns.
Abstract: A classification of models for animating synthetic actors is proposed. The classification depends on the motion control method used (geometric, physical, or behavioral) and the type of actor interaction (single actor, actor-actor, actor-environment, and animator-actor). These interactions and models give rise to a classification array with four rows and three columns. Each case represents existing and potential approaches to animation control. The characteristics of each motion control method and interaction type are examined. >
115Â citations
TL;DR: Visualizing two types of scattered data-volumetric data sampled in a three-dimensional volume and surface-on-surface data sampled on aThree-dimensional surface-is addressed.
Abstract: Visualizing two types of scattered data-volumetric data sampled in a three-dimensional volume and surface-on-surface data sampled on a three-dimensional surface-is addressed. Since measurements are often sampled at discrete scattered locations, mathematical models that are defined over the entire domain and that interpolate or approximate the given scattered data are used. The modeling function can be evaluated over a grid, so that a conventional, off-the-shelf visualization tool that applies to data on a uniform grid can be used. Volumes, gradient, centroids, and other quantities can be computed from the model. Even though the two kinds of data and their problems look similar in their mathematical descriptions, they are solved by different methods, and the various solutions are visualized with methods that are quite different. >
TL;DR: The Heidelberg ray tracing model, developed especially for visualization of medical images, is based on a global illumination model and contains a number of application-specific assumptions that simulates the projection of a scene with well-defined lighting.
Abstract: The Heidelberg ray tracing model, developed especially for visualization of medical images, is based on a global illumination model and contains a number of application-specific assumptions. It simulates the projection of a scene with well-defined lighting. A detailed description of the model follows an overview of existing and competing illumination procedures. >
TL;DR: The process of matching the type of information of interest with the ability of the different representation properties to convey this information is formalized in a generic framework and the advantages over ad hoc display approaches are examined.
Abstract: The process of matching the type of information of interest with the ability of the different representation properties to convey this information is formalized in a generic framework. Visualization approaches are discussed, and the natural scene paradigm on which the methodology for choosing a representation is based is described. Data types and interpretation aims are explored. The use of the paradigm, the matching process, and implementation and display of the representation are described. The advantages of the methodology over ad hoc display approaches are examined. >
TL;DR: It is demonstrated that these techniques for plotting scalar fields on an N-dimensional lattice work for such data visualization tasks as the location of maxima, minima, saddle points, and other features, as well as for visually fitting multivariate data and the visual determination of dominant and weak or irrelevant variables.
Abstract: The problem of visualizing a scalar-dependent variable that is a function of many independent variables is addressed, focusing on cases with three or more independent variables. A hierarchical axis using different metrics for each independent variable is used, as are hierarchical data symbols. The technique is described for the case in which each independent variable is sampled in a regular grid or lattice-like fashion (that is, in equal increments), but it can be generalized to a variety of less restrictive domains. Rather than presenting a formal mathematical description, the authors use a visual means of describing the technique for a simple three-dimensional data case, and then demonstrate by example how to extend it to higher dimensions. It is demonstrated that these techniques for plotting scalar fields on an N-dimensional lattice work for such data visualization tasks as the location of maxima, minima, saddle points, and other features, as well as for visually fitting multivariate data and the visual determination of dominant and weak or irrelevant variables. >
TL;DR: A set of tools, called the Multimedia Works software environment, consists of three programs: Media Space, a multimedia database and research program; Multimedia works Composer, a storyboarding and presentation program; and Video Light Table, a direct manipulation video-clip editor.
Abstract: The creation of multimedia composition tools for young learners is addressed. The factors to consider in designing composing tools are discussed. Such a set of tools, called the Multimedia Works software environment, is described. It consists of three programs: Media Space, a multimedia database and research program; Multimedia Works Composer, a storyboarding and presentation program; and Video Light Table, a direct manipulation video-clip editor. The use of student participation in developing the tools is also described. Some problems that are being worked on are examined. >
TL;DR: An algorithm that automatically produces polygonal representations of 3-D structures within a volume from a set of cross-sectional images is presented, and can be used to describe and visualize normal as well as pathological anatomy.
Abstract: An algorithm that automatically produces polygonal representations of 3-D structures within a volume from a set of cross-sectional images is presented. The method incorporates the requirements necessary for structure analysis to go beyond plain rendering. The algorithm is fully automatic, using local voxel values to determine the connectivity of the surface. The resulting polygons are coherently ordered and connected, and no polygon occurs more than once. Each surface is complete, that is, no holes occur (except as an option, on the boundaries of the volume). The algorithm can be used to describe and visualize normal as well as pathological anatomy. >
TL;DR: An approach to boundary evaluation and a boundary representation that merges the input primitives into a single representation and selects the entities in the merged set that constitute the result of the Boolean operations.
Abstract: An approach to boundary evaluation and a boundary representation are presented. The approach uses nonmanifold topology (NMT) to overcome editing and coverage limitations associated with the manifold nature of existing boundary evaluation schemes. It merges the input primitives into a single representation and selects the entities in the merged set that constitute the result of the Boolean operations. Because this approach maintains a complete description of the input primitives, it provides some significant performance advantages when editing. In addition, the domain of 3D Boolean operations is extended to include surface and wireframe information as well as the traditional solid information. The implementation and testing of the approach are discussed. >
TL;DR: An optical noncontact 3-D digitizing system developed to acquire, process, display, and replicate the surface of the human head is described and the modification of the digitizer to help plan and evaluate facial plastic surgery is discussed.
Abstract: An optical noncontact 3-D digitizing system developed to acquire, process, display, and replicate the surface of the human head is described. The modification of the digitizer to help plan and evaluate facial plastic surgery is discussed. The quality and accuracy of the images produced are examined, and some medically relevant results are considered. >
TL;DR: By combining polygon scan-conversion with a dynamic screen data structure, the technique provides significant speedup in the display time of polygonal scenes that depend on BSP trees, especially in cases where the number of polygons is large.
Abstract: A technique for displaying binary space partitioning (BSP) trees that is faster than the usual back-to-front display method is presented. By combining polygon scan-conversion with a dynamic screen data structure, the technique, a front-to-back approach, provides significant speedup in the display time of polygonal scenes that depend on BSP trees, especially in cases where the number of polygons is large. This speedup is confirmed by applying the technique to randomly generated triangles. >
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TL;DR: The topic of multimedia is reviewed by discussing its various definitions, which are used as a framework for examining the issues and problems encountered by multimedia systems.
Abstract: The topic of multimedia is reviewed by discussing its various definitions. These definitions are used as a framework for examining the issues and problems encountered by multimedia systems. Hardware issues, nonsequential access, information programming, time programming, and new user interfaces are among the topics addressed. >
TL;DR: The standard computer graphics transform-clip-draw pipeline is described, and an overview of the clipping function is given, and a simple algorithm for performing line clipping is presented.
Abstract: The standard computer graphics transform-clip-draw pipeline is described, and an overview of the clipping function is given. A simple algorithm for performing line clipping is presented. Homogeneous clipping, Z clipping, and global clipping using the algorithm are discussed. >
TL;DR: A set of tools called MPR Edit (multiplanar reconstruction editor) is presented, designed like a paint and drawing program for 3-D data sets, that allows the interactive creation of shapes that define volumes of interest in images of medical data.
Abstract: A set of tools called MPR Edit (multiplanar reconstruction editor) is presented. Designed like a paint and drawing program for 3-D data sets, MPR Edit allows the interactive creation of shapes that define volumes of interest in images of medical data. The implementation of MPR Edit is described, and examples of its use are given. Clinical applications are discussed. >
TL;DR: The use of a ray-tracing model that takes into account any kind of film layer in any medium to emulate interference color is reported, based on physics and Fresnel's formulas.
Abstract: The use of a ray-tracing model that takes into account any kind of film layer in any medium to emulate interference color is reported. The method is based on physics and Fresnel's formulas. The physics of the phenomena is explained, the implementation is described, and some results are presented. >
TL;DR: Analysis and visualization with Media View are examined, including linking to Mathematica, producing locally derived animations, visualizing remotely produced data sets, and viewing video sequences.
Abstract: Media View, a system that can be used to produce an electronic document containing mathematics, data sets, and associated visualizations, is discussed. Animations and other substructures persist through electronic mailing and can be awakened by the recipient. The features of Media View documents are described. Analysis and visualization with Media View are examined, including linking to Mathematica, producing locally derived animations, visualizing remotely produced data sets, and viewing video sequences. The architectural details of Media View are discussed. >
TL;DR: In this paper, a pixel-selected ray tracing (PSRT) algorithm was proposed to reduce the number of pixels whose intensity must be calculated by ray tracing. But, the method is not suitable for high-resolution images, as it can result in some image quality defects, because small objects and parts of thin or wedge-shaped objects may disappear when they are located between the initially sampled pixels.
Abstract: An acceleration method based on an idea that T Whitted (Commun ACM, vol23, no6 pp343-349, June 1980) presented on ray tracing is discussed He proposed making antialiased images by hierarchical adaptive oversampling The present authors use hierarchical adaptive undersampling to reduce the number of pixels whose intensity must be calculated by ray tracing To implement pixel-selected ray tracing (PSRT), homogeneous regions in images must first be found Generally, adaptive undersampling can result in some image-quality defects, because small objects and parts of thin or wedge-shaped objects may disappear when they are located between the initially sampled pixels PSRT has an improved algorithm that uses pixels with the correct object information from among the sampled pixels to find pixels with erroneous color and correct them Moreover, PRST uses ray-object intersection trees for precise classification of the homogeneity of regions and for fast intensity calculation in homogeneous regions Experimental results are presented They show that PSRT is two to nine times faster than standard ray tracing >
TL;DR: A way to add boxes, called the S-bounds method, is described, and work to data on extending it is summarized, which is useful for interference-detection and collision-detector problems.
Abstract: Testing for intersection between geometric entities in ray casting is normally performed by intersecting a ray (a semi-infinite line) against the surface elements of a geometric model. Simple reasoning about the extent of each geometric entity significantly reduces the time required by such algorithms. If the ray and the geometric entities are boxed, one first tests to see whether the box around the ray and the box around a geometric entity overlap. Only if the boxes overlap does one continue to test to determine whether the ray and the entity overlap. A way to add boxes, called the S-bounds method, is described, and work to data on extending it is summarized. The method is useful for interference-detection and collision-detection problems. >
TL;DR: In this article, the use of floating-point pixel space for subpixel subdividing pixels into subpixelic particles is discussed, and integer arithmetic in addition to subsampling is briefly discussed.
Abstract: Reasons for subdividing pixels into subpixelic particles are discussed. Working with subpixel resolution in the floating-point domain is suggested as the easiest approach. To illustrate the use of floating-point pixel space, the arithmetic of two rendering algorithms is reviewed. The algorithms are an antialiased line renderer and a simple polygon tiler. Another use for subpixel resolution, i.e., doing antialiasing by subsampling is also considered. Using integer arithmetic in addition to subsampling is briefly discussed. >
TL;DR: A version based on the properties of linear Diophantine equations that can speed scan conversion by a factor of almost five is presented.
Abstract: The line segment is the basic entity in virtually all computer graphics systems. J.E. Bresenham's algorithm (1965) efficiently scan converts line segments because it requires only an integer addition and a sign test for each pixel generated. It is the standard for scan converting a line segment. A version based on the properties of linear Diophantine equations that can speed scan conversion by a factor of almost five is presented. Two approaches are used to achieve speedup. One is to parallelize the line generation process. The other is to take advantage of the repeated patterns that the algorithm generates. >
TL;DR: An approach to summarizing and understanding medical image data sets is presented, and a general, mathematically based method for building sign systems that uses differentiable topology and semiotics is presented.
Abstract: An approach to summarizing and understanding medical image data sets is presented. It is a general, mathematically based method for building sign systems that uses differentiable topology and semiotics. The semiotics of medical imaging is first examined, covering display requirements, control parameters, icons and topological constraints, and signs and data reduction. The general approach is then applied to projection imaging as a paradigm for efficient synthetic display devices. Singularities and contrast curves, generic signs for single projections, and interactively controlled projections are considered. Signs for sequence displays are discussed, and sectional imaging is treated. Qualitative interactions between systems are briefly addressed. >
TL;DR: The use of spreadsheets to bring hypermedia to the office is proposed, and it is argued that the numeric cell is a powerful generic object type, and its use is explored.
Abstract: The use of spreadsheets to bring hypermedia to the office is proposed. It is argued that the numeric cell is a powerful generic object type, and its use is explored. The application of Hypercalc (a prototype hypermedia spreadsheet constructed by combining an authoring interface with a series of video device drivers written for Informix's Wingz, a graphical spreadsheet with a built-in scripting language) to a business case study is described. The tools of the resulting environment, called Hypercase, are discussed. The limitations of the traditional monomedia approach to business case studies are outlined. >