Showing papers in "IEEE Computer Graphics and Applications in 1986"
TL;DR: A uniform framework for representing and using world projections is proposed and it is argued that the best general-purpose representation is the is projection onto a cube.
Abstract: Various techniques have been developed that employ projections of the world as seen from a particular viewpoint. Blinn and Newell introduced reflection mapping for simulating mirror reflections on curved surfaces. Miller and Hoffman have presented a general illumination model based on environment mapping. World projections have also been used to model distant objects and to produce pictures with the fish-eye distortion required for Omnimax frames. This article proposes a uniform framework for representing and using world projections and argues that the best general-purpose representation is the is projection onto a cube. Surface shading and texture filtering are discussed in the context of environment mapping, and methods are presented for obtaining diffuse and specular surface illumination from prefiltered environment maps. Comparisons are made with ray tracing, noting that two problems with ray tracing?obtaining diffuse reflection and antialiasing specular reflection?can be handled effectively by environment mapping.
590 citations
TL;DR: A novel method for modeling swept voume by computing a family of critical curves from a moving solid is presented, developed for real-time verification of NC tool paths using computer graphics.
Abstract: The modeling of swept volume is important in simulating the interference between a moving solid and its environment. This article presents a novel method for modeling swept voume by computing a family of critical curves from a moving solid. Based on this approach, a system has been developed for real-time verification of NC tool paths using computer graphics.
373 citations
TL;DR: 3DDDA as mentioned in this paper is a 3D line generator for efficient traversing of both structures and provides an order of magnitude improvement in processing speed compared to other known ray-tracing methods.
Abstract: In this article we propose algorithms that address the two basic problems encountered in generating continuous-tone images by ray tracing: speed and aliasing. We examine previous approaches to the problem and then propose a scheme based on the coherency of an auxiliary data structure imposed on the original object domain. After investigating both simple spatial enumeration and a hybrid octree approach, we developed 3DDDA, a 3D line generator for efficient traversing of both structures. 3DDDA provides an order of magnitude improvement in processing speed compared to other known ray-tracing methods. Processing time is found to be virtually independent of the number of objects involved in the scene. For large numbers of objects, this method actully becomes faster than scan-line methods. To remove jags from edges, a scheme for identifying edge orientation and distance from pixel center to true edge has been implemented. The time required for antialiasing depends on the total length of the edges encountered, but it is normally only a fractional addition to the time needed to produce the scene without antialiasing.
335 citations
TL;DR: This application presents a method for creating Omnimax projections from multiple perspective views, and uses a space-variant filter for this application that computes a weighted average over an arbitrarily oriented elliptical area.
Abstract: Creation of Omnimax animation by computer opens up fantastic new visual possibilities. Unfortunately, the fish-eye distortion of Omnimax film images complicates synthesis by computer, since most image-synthesis programs can create only perspective views. As an alternative to modifying existing image-synthesis programs to produce Omnimax projections directly, we present a method for creating them from multiple perspective views. Four perspective views of the environment are created, each a projection onto a face of a cube centered at the camera, and then a mapping program creates an Omnimax projection from them. To minimize aliasing during resampling, the mapping program uses the elliptical weighted average filter, a space-variant filter we developed for this application that computes a weighted average over an arbitrarily oriented elliptical area. This filter can also be used for texture mapping 3D surfaces.
294 citations
TL;DR: New procedures are described to predict the global illumination function without excessive computational expense and indicate the enormous potential of this approach for realistic image synthesis, particularly for dynamic images of static environments.
Abstract: The radiosity method models the interaction of light between diffusely reflecting surfaces and accurately predicts the global illumination effects Procedures are now available to simulate complex environments including occluded and textured surfaces For accurate rendering, the environment must be discretized into a fine mesh, particularly in areas of high intensity gradients The interdependence between surfaces implies solution techniques which are computationally intractable This article describes new procedures to predict the global illumination function without excessive computational expense Statistics indicate the enormous potential of this approach for realistic image synthesis, particularly for dynamic images of static environments
271 citations
TL;DR: Several surface analysis tools useful in detecting anomalous surface features including standard techniques such as contouring and high-resolution shaded image displays based on direct ray tracing, and some novel methods such as maps of the principal curvatures, the integration of lines of curvature to show the variation ofthe principal directions.
Abstract: Parametric polynomial surfaces defined to satisfy given interpolatory or boundary constraints often suffer extraneous undesired features because of poor control over their many degrees of freedom. Current techniques for detecting and remedying such unexpected surface characteristics are primitive and inadequate. This article describes several surface analysis tools useful in detecting such anomalous surface features. These include standard techniques such as contouring and high-resolution shaded image displays based on direct ray tracing, and some novel methods such as maps of the principal curvatures, the integration of lines of curvature to show the variation ofthe principal directions, and the determination of geodesic paths on the surface.
161 citations
TL;DR: A new method to reduce shadow testing time during ray tracing is presented, which involves generating light buffers, each of which partition the environment with respect to an individual light source.
Abstract: In one area of computer graphics, realistic image synthesis, the ultimate goal is to produce a picture indistinguishable from a photograph of a real environment. A particularly powerful technique for simulating light reflection-an important element in creating this realism-is called ray tracing. This method produces images of excellent quality, but suffers from lengthy computation time that limits its practical use. This article presents a new method to reduce shadow testing time during ray tracing. The technique involves generating light buffers, each of which partition the environment with respect to an individual light source. These partition descriptions are then used during shadow testing to quickly determine a small subset of objects that may have to be tested for intersection. The results of timing tests illustrate the beneficial performance of these techniques. The tests compare the standard ray-tracing algorithm to light buffers of varying resolution.
147 citations
TL;DR: This work addresses the problem of mapping undistorted planar textures onto arbitrarily represented surfaces by mapping two-dimensional texture patterns onto three-dimensional curved surfaces with relatively low distortion.
Abstract: Most published techniques for mapping two-dimensional texture patterns onto three-dimensional curved surfaces assume that either the texture pattern has been predistorted to compensate for the distortion of the mapping or the curved surfaces are represented parametrically. We address the problem of mapping undistorted planar textures onto arbitrarily represented surfaces. Our mapping technique is done in two parts. First the texture pattern is embedded in 3-space on an intermediate surface. Then the pattern is projected onto the target surface in a way that depends only on the geometry of the target object (not on its parameterization). Both steps have relatively low distortion, so the original texture need not be predistorted. We also discuss interactive techniques that make two-part mapping practical.
129 citations
TL;DR: Because of the complete and continuous nature of the resampling algorithm, the resulting image is free of the classic sampling artifacts such as graininess, degradation, and edge aliasing.
Abstract: A two-pass spatial transform technique that does not exhibit the aliasing artifacts associated with techniques for spatial transform of discrete sampled images is possible through the use of a complete and continuous resampling interpolation algorithm. The algorithm is complete in the sense that all the pixels of the input image under the map of the output image fully contribute to the output image. It is continuous in the sense that no gaps or overlaps exist in the sampling of the input pixels and that the sampling can be performed with arbitrary precision. The technique is real time in the sense that it can be guaranteed to operate for any arbitrary transform within a given time limit. Because of the complete and continuous nature of the resampling algorithm, the resulting image is free of the classic sampling artifacts such as graininess, degradation, and edge aliasing.
123 citations
TL;DR: This work presents a method of generating specific color sequences within the framework of a uniform color space, allowing for the intuitive specification of color sequences and for their realization on various display systems.
Abstract: Recent technological advances have made it feasible to produce full color statistical maps on computer-controlled display systems. This has caused an appraisal of the use of color to represent statistical variables, and the development of a theoretical structure for the choice of suitable univariate and bivariate map coloring schemes. Realization of such schemes in an intuitive and controlled way is important to the comprehension of statistical variables from maps. Therefore, we present a method of generating specific color sequences within the framework of a uniform color space, allowing for the intuitive specification of color sequences and for their realization on various display systems.
121 citations
TL;DR: A method for using ray tracing to render spline surfaces that is suitable for any object generated from control vertices via tensor-product B-splines, and makes use of kajiya's work on ray tracing procedurally defined surfaces.
Abstract: We present a method for using ray tracing to render spline surfaces?one that is suitable for any object generated from control vertices via tensor-product B-splines. The method derives from kajiya's work on ray tracing procedurally defined surfaces1 and makes use of two preprocessing steps. One involves the controlvertex refinement recurrences due to Riesenfeld et. al.2, and the second generates a tree of nested bounding boxes. Intersection testing involves running Kajiya's algorithm on the tree, followed by two to three (on the average) iterations of Newton's method.
TL;DR: A new version of Crow's algorithm is presented, developed at the Universite de Montreal, which attempts a less constrained environment and allows penetration between polygons, and any number of light sources can be defined anywhere in 3D space, including the view volume and any shadow volume.
Abstract: In 1977 Frank Crow introduced a new class of algorithm for the generation of shadows. His technique, based on the concept of shadow volumes, assumes a polygonal database and a constrained environment. For example, polyhedrons must be closed, and polygons must be planar. This article presents a new version of Crow's algorithm, developed at the Universite de Montreal, which attempts a less constrained environment. The method has allowed the handling of both open and closed models and nonplanar polygons with the viewpoint anywhere, including any shadow volume. It does not, however, sacrifice the essential features of Crow's original version: penetration between polygons is allowed and any number of light sources can be defined anywhere in 3D space, including the view volume and any shadow volume. The method has been used successfully in the film Tony de Peltrie and is easily incorporated into an existing scan-line, hidden-surface algorithm.
TL;DR: The z-buffer display algorithm operates directly on CSG, does not require explicit boundary data, and is easier to implement than ray casting, which may lead to machines simpler than those now being built for ray casting.
Abstract: Solid modelers based on constructive solid geometry (CSG) typically generate shaded displays directly from CSG by using ray-casting techniques, which do not require informatin on the faces, edges, and vertices that bound a solid. This article describes an alternative-a simple new algorithm based on a depth-buffering or z-buffering approach. The z-buffer display algorithm operates directly on CSG, does not require explicit boundary data, and is easier to implement than ray casting. Ray-casting and z-beffering algorithms have comparable performances, but z-buffering is often faster for objects with complex surfaces, because it avoids expensive curve/surface intersection calculations. Because of their simplicity, depth-buffering algorithms for CSG are well-suited to hardware implementations, and may lead to machines simpler than those now being built for ray casting.
TL;DR: This article describes and presents examples of some techniques for the representation and interactive design of surfaces based on a parametric surface representation that user v-spline curves and extends their application to a rectangular grid of control points.
Abstract: This article describes and presents examples of some techniques for the representation and interactive design of surfaces based on a parametric surface representation that user v-spline curves. These v-spline curves, similar in mathematical structure to v-splines, were developed as a more computationally efficient alternative to splines in tension. Although splines in tension can be modified to allow tension to be applied at each control point, the procedure is computationally expensive. The v-spline curve, however, uses more computationally tractable piecewise cubic curves segments, resulting in curves that are just as smoothly joined as those of a standard cubic spline. After presenting a review of v-splines and some new properties, this article extends their application to a rectangular grid of control points. Three techniques and some application examples are presented.
TL;DR: This article describes work in tiled window management featuring a constraint-based layout mechanism that the user can specify the appearance of individual windows and constrain relationships between windows, thus exercising necessary control over the tiling process.
Abstract: Typical computer workstations employ window managers for creating, destroying, and arranging windows on the screen. Window managers generally follow either a desktop metaphor, allowing windows to overlap each other like sheets of paper on a desk, or they use a tiling model, arranging each window with a specific size and location that avoids overlap. Desktop models allow for the most layout freedom, but can be frustrating to use when dealing with a large number of windows that must all be visible at once. Tiling models guarantee that each window will be completely visible on the screen, but thus far have provided relatively poor mechanisms for controlling layout decisions. This article describes work in tiled window management featuring a constraint-based layout mechanism. With it the user can specify the appearance of individual windows and constrain relationships between windows, thus exercising necessary control over the tiling process. We discuss our constraint model and then detail an implementation approach that would make use of those constraints.
TL;DR: A system that renders a scene by ray tracing from a directed acyclic graph, made efficient for large models by using an adaptive method of space division to reduce the number of intersection calculations needed.
Abstract: A system of Constructive Solid Geometry (CSG) enables an engineering designer to compose threedimensional shapes by combining simpler ones. Definitions of such objects are represented by tree structures or directed acyclic graphs. Most existing systems convert this representation to a more conventional boundary representation of the solids in order to render pictures from the model. More recently, a number of systems have been described that render the pictures directly from the CSG structure. We describe such a system. We render a scene by ray tracing from a directed acyclic graph. This process is made efficient for large models by using an adaptive method of space division to reduce the number of intersection calculations needed.
TL;DR: A prototype Process Visualization System (PVS) is developed that allows nonprogrammers to construct graphics displays, and to establish relationships between these displays and changes in the data describing the process being monitored.
Abstract: An increasingly important use of computer graphics is to monitor such real-world processes as manufacturing plants, power plants, and refineries. As in many uses of computer graphics, the development of this application area has been programmer-intensive. As a consequence, system are being developed more slowly than is desired and they cost more than necessary. This article discusses some of the key issues and requirements involved in designing productivity tools for use in constructing monitoring systems. We have developed a prototype Process Visualization System (PVS) that allows nonprogrammers to construct graphics displays, and to establish relationships between these displays and changes in the data describing the process being monitored. With this system, customized, dynamically updated scenes can be created. The PVS allows users to construct symbols, to place them on the screen, and to connect them to data items from the monitored processes' database. Using this system frees the end-user from reliance on programmers, and allows the user to quickly display the data items of interest.
IBM1
TL;DR: In the early 1980's, large computing systems became capable of supporting response times of 300 ms for transactions consisting of 500,000 instructions, which produced an unexpectedly large increase in the productivity of scientists, engineers, and programmers.
Abstract: In the early 1980's, large computing systems became capable of supporting response times of 300 ms for transactions consisting of 500,000 instructions. In interactive environments this produced an unexpectedly large (±100 percent) increase in the productivity of scientists, engineers, and programmers. An investigation of the findings by cognitive researchers led to a reconciliation of the productivity improvement and response time. This article examines the implications of this, and suggests several strategies for further productivity improvements. Cognitive research models are augmented with additional theory to develop an analytic model of interaction between the problem-solver and the computational system. This analytic model predicts that improvements in system response time and data entry technology can produce even greater gains in productivity.
TL;DR: This tutorial examines resultants, curve implicitization, curve inversion, and curve intersection, which deals strictly with algorithms and introduces abstractions far removed from the algorithmic nature of computer-aided design.
Abstract: Classical algebraic geometry has been virtually ignored in computer-aided geometric design. However, because it deals strictly with algorithms, it is really more suited to this field than is modern algebraic geometry, which introduces abstractions far removed from the algorithmic nature of computer-aided design. This tutorial examines resultants, curve implicitization, curve inversion, and curve intersection. Discussion follows a series of examples simple enough for those with only a modest algebra background to follow.
TL;DR: An algorithm for computing these operations that uses a boundary classification technique is presented here, which is recursive in structure, with the recursion being on the dimensions of objects dealt with at each stage.
Abstract: Computation of the union, intersection, and difference of n-dimensional objects plays a central role in several computer-aided geometric design problems. An algorithm for computing these operations that uses a boundary classification technique is presented here. The algorithm is recursive in structure, with the recursion being on the dimensions of objects dealt with at each stage. The representation treats all entities as objects, making no distinction between faces, edges, or vertices. The objects produced are "regularized"; that is, there are no degenerate boundaries such as dangling edges. The sample application given involves hidden-surface removal.
TL;DR: This article describes some intial steps in the field of computer-aided neuroanatomy, an algorithm for unfolding and flattening cortical surfaces and a measurement of the differential geometric aspects of these surfaces are presented.
Abstract: In a variety of species including monkeys and humans, the surface of the retina is mapped in an accurate manner to the surface of primary visual cortex. In a real sense there is an image, expressed in the firing density of neurons, impressed on the surface of the brain. The various images found in the brain have complicated natures: They are ``distorted'' by nonlinear map functions, and contain submodality information expressed spatially in the form of columnar systems representing stereo, orientation, motion, and other forms of data. The detailed study of such maps represents a difficult series of problems in the areas of computer graphics, image processing, numerical analysis, and neuroanatomy. This article describes some intial steps in the field of computer-aided neuroanatomy. An algorithm for unfolding and flattening cortical surfaces and a measurement of the differential geometric aspects of these surfaces are presented. Models of the structure of images as they would appear mapped to the surface of primate striate cortex are also shown.
TL;DR: Some methods are described that keep the surface degree low, while retaining many of the advantages of sculptured surfaces, when integrating this technology into boundary representation and constructive solid geometry (CSG) solid modelers.
Abstract: The fields of surface modeling and solid modeling have been developing quite independently. Today users of each system find they must employ functionality traditionally present only in the other system. This article focuses on issues related to the incorporation of sculptured surface functionality into solid modeling systems. Mathematical concepts related to sculptured surface modeling are reviewed and approaches to the representation of intersection curves and trimmed surfaces are discussed. Difficulties arise from the high polynomial degree resulting from many free-form surface operations. Some methods are described that keep the surface degree low, while retaining many of the advantages of sculptured surfaces. Compromises may be required when integrating this technology into boundary representation (B-rep) and constructive solid geometry (CSG) solid modelers.
TL;DR: This article describes a method of representing a solid design procss using a tree structure that supposrts UNDO and REDO operations for regenerating any solid in a previous stage of the design.
Abstract: This article describes a method of representing a solid design procss using a tree structure. This representation supposrts UNDO and REDO operations for regenerating any solid in a previous stage of the design. The implementations of invertible set operations is also given in detail.
TL;DR: The applicability of different display methods for different types of volumes, the advantages and disadvantages of different techniques, and the results of experiments when image processing techniques were applied before the images were displayed are reviewed.
Abstract: The advent of inexpensive, high-speed processing and storage has fueled interest in new ways to process and display 3D images. This new discipline of 3D imaging promises to produce a wealth of exciting applications in many fields. For three years, engineers at Linkoping University have experimented with algorithms and methods to display 3D images obtained from a variety of sources, including computer-aided tomography, transmission electron microscopy, and laser microscopy. This article reviews the applicability of different display methods for different types of volumes, the advantages and disadvantages of different techniques, and the results of experiments when image processing techniques were applied before the images were displayed.
TL;DR: The goals and underlying model of PHIGS are described, its capabilities are reviewed, its similarities and differences are discussed, and some brief application examples are provided.
Abstract: The Programmer's Hierarchical Interactive Graphics System (PHIGS) is a draft standard for computer graphics programming. PHIGS is useful for applications that manipulate complex displays of 2D or 3D data in a highly interactive environment. This is done through the hierarchical data organization and flexible editing capabilities provided in PHIGS. This article describes the goals and underlying model of PHIGS, reviews its capabilities, and provides some brief application examples. The similarities and differences of PHIGS and GKS are discussed.
TL;DR: This article gives three viewing-transformation algorithms for displaying on a screen 3D pictures represented by linear octrees that take advantage of the recursive labeling used to identify the successive decomposition of an object into octants.
Abstract: This article gives three viewing-transformation algorithms for displaying on a screen 3D pictures represented by linear octrees. All the procedures take advantage of the recursive labeling used to identify the successive decomposition of an object into octants. The first algorithm performs transformations directly on the linear octree, while the second and third algorithms determine the 3D border of the given object first and then project onto the screen the surface voxels thus found. All the algorithms perform the viewing transformations in O(RN) time, where R is the resolution of the picture and N is the number of elements in the linear octree. One of the algorithms provides views of the object at different layers of gray level, while another allows internal views.
TL;DR: A sampling data display to solid modeling, shows that significant improvements in interactivity can be obtained by microprogramming a high-performance, general-purpose display architecture.
Abstract: Interactive computer graphics display requirements have generally been met is one of two ways: by highly specialized systems designed for a particular application, or, more frequently, by devices with a limited set of display functions common to a wide range of applications. A third alternative, presented here, is to use a high-performance, general-purpose display architecture to provide both common and application-specific graphics functions. A sampling data display to solid modeling, shows that significant improvements in interactivity can be obtained by microprogramming such a machine.
Journal Article•
TL;DR: This article examines some of the desirable features of ß-splines that make them particularly suitable for computer-aided design and discusses the concept of geometric continuity, which is derived upon the control vertices to ensure that the design curve has second-order geometric continuity.
Abstract: This article examines some of the desirable features of ß-splines that make them particularly suitable for computer-aided design. First, a theoretical analysis is presented regarding the effects upon the shape of a design curve when the bias and tension parameters are allowed to vary in certain ways. Second, the concept of geometric continuity is discussed, and conditions are derived upon the control vertices to ensure that the design curve has second-order geometric continuity. Illustrations of ,ß-spline curves are presented to support the theoretical conclusions.
TL;DR: A new system, Pixel-powers, has been designed for the rapid rendering of curved surfaces that can directly evaluate quadratic expressions of the form Ax2 + Bxy + Cy2 + Dx + Ey + F for every pixel (x,y) in the image in parallel.
Abstract: A new system, Pixel-powers, has been designed for the rapid rendering of curved surfaces. This system is a generalization of the design of our logic-enhanced framed buffer memory system, Pixel-planes. Our new design can directly evaluate quadratic expressions of the form Ax2 + Bxy + Cy2 + Dx + Ey + F for every pixel (x,y) in the image in parallel. Sample images generated by a high-level simulation of the new system are shown.
TL;DR: The 34010 Graphics System Processor is a 32-bit graphics microprocessor capable of executing high-level languages and combines a full general-purpose instruction set with a powerful set of graphics instructions that includes arithmetic as well as Boolean pixbits (pixel block transfers).
Abstract: The 34010 Graphics System Processor is a 32-bit graphics microprocessor capable of executing high-level languages. It combines a full general-purpose instruction set with a powerful set of graphics instructions that includes arithmetic as well as Boolean pixbits (pixel block transfers). Because it is completely programmable, the 34010 can be used in many different graphics and nongraphics applications. it was designed to support a wide range of display resolutions and pixel sizes, as well as applications such as page (laser) printers, ink jet printers, data compression, and facsimile transmission. The 34010 includes such system features as an on-board instruction cache, full interrupt capability, wait and hold functions, and display timing control, as well as test and emulation support. Unique among today's microprocessors, the 34010 addresses all memory down to the bit level with variably sized fields rather than the common byte or word addressing. For example, the 34010 can push a 5-bit quantity onto a stack. This field-processing capability is an integral part of the basic architecture.