Showing papers in "IEEE Computer Graphics and Applications in 1984"
TL;DR: In this article, an octree-based algorithm is proposed to reduce the number of time-consuming object-ray intersection calculations by associating a given voxel with only those objects whose surfaces pass through the volume of the Voxel, which makes possible the ray tracing of complex scenes by medium-scale and small-scale computers.
Abstract: An algorithm is described that speeds up ray-tracing techniques by reducing the number of time-consuming object-ray intersection calculations that have to be made. The algorithm is based on subdividing space into an octree, associating a given voxel with only those objects whose surfaces pass through the volume of the voxel. It includes a technique for obtaining fast access to any node and a mechanism for finding the next node intersected by a ray when it has hit nothing in the current node. This new algorithm makes possible the ray tracing of complex scenes by medium-scale and small-scale computers.
664 citations
TL;DR: An organization of interaction techniques, based on the user tasks for which the techniques are used, is proposed, suggesting that task requirements limit the set of techniques that can be considered for a particular application.
Abstract: An organization of interaction techniques, based on the user tasks for which the techniques are used, is proposed. It is suggested that task requirements limit the set of techniques that can be considered for a particular application. The characteristics of a variety of techniques are enumerated and many of the considerations important to their effectiveness are discussed. Relevant experimental and experiential comparisons are tabulated.
377 citations
TL;DR: It may be true, as the poet said, that only God can make a tree, but through geometric modeling a computer graphics system can produce a remarkable likeness.
Abstract: It may be true, as the poet said, that ?...only God can make a tree,? but through geometric modeling a computer graphics system can produce a remarkable likeness.
273 citations
TL;DR: An offset capability for planar curves and profiles in a solid modeler leads to the solution of some practical design problems.
Abstract: An offset capability for planar curves and profiles in a solid modeler leads to the solution of some practical design problems.
194 citations
TL;DR: An approach to the problem of deriving a 2-D display of a 3-D object is described that is quite different from previous methods in that boundary detection and hidden-surface removal are not carried out explicitly.
Abstract: An approach to the problem of deriving a 2-D display of a 3-D object is described that is quite different from previous methods in that boundary detection and hidden-surface removal are not carried out explicitly. The method uses a scan-line representation of three-dimensional objects.
139 citations
TL;DR: Low-cost PCs and workstations with bit-mapped graphics possess limited processing power, so efficient algorithms are needed to draw curves interactively.
Abstract: Low-cost PCs and workstations with bit-mapped graphics possess limited processing power. As a result, efficient algorithms are needed to draw curves interactively.
127 citations
TL;DR: Some broad principles for the effective use of color are established on the basis of the mechanisms of human color perception and some functional relationships that should improve the visual effectiveness of color display are derived.
Abstract: Some broad principles for the effective use of color are established on the basis of the mechanisms of human color perception. Some functional relationships that should improve the visual effectiveness of color display are derived.
124 citations
TL;DR: Here, together with their formal definitions and related algorithms, are two data structures more suitable for graphics operations that are not always a desirable data structure.
Abstract: The octree is not always a desirable data structure. Here, together with their formal definitions and related algorithms, are two data structures more suitable for graphics operations.
124 citations
TL;DR: In this approach, the parametric form is applied without the usual computational nightmare, relying on subdivision algorithms.
Abstract: In this approach, the parametric form is applied without the usual computational nightmare. The key is to view the parametric range as an interval, relying on subdivision algorithms.
122 citations
TL;DR: An algorithm is developed that combines an existing shadowing method with a popular visible surface rendering technique, called a depth buffer, to generate soft shadows resulting from light sources of finite extent.
Abstract: A pragmatic approach is taken to develop an algorithm that combines an existing shadowing method with a popular visible surface rendering technique, called a depth buffer, to generate soft shadows resulting from light sources of finite extent. The method extends F. Crow's shadow volume algorithm (1977) to produce multiple shadows overlapped to yield the characteristic soft edges of a shadow penumbra.
111 citations
TL;DR: A simple and systematic method is described for calculating the integral of a polynomial function over an arbitrary nonconvex polyhedron and the practical accuracy of the result is within the accuracy of floating-point arithmetic.
Abstract: A simple and systematic method is described for calculating the integral of a polynomial function over an arbitrary nonconvex polyhedron. First a general formula is presented for direct evaluation of the integral of a polynomial over a 3-D simplex. An integral over a polyhedron can then be easily calculated by using the central projection method and decomposing a polyhedron symmetrically into a set of simplices and accumulating the results from each simplex based on this formula. This method adopts a systematic and automatic decomposition. It is analytically exact, but the practical accuracy of the result is within the accuracy of floating-point arithmetic. Furthermore, the time complexity of this method is linearly proportional to the number of vertices of a polyhedron.
TL;DR: For realistic simulation it is necessary to thoroughly define and describe light-source characteristics, especially the light- source geometry and the luminous intensity distribution.
Abstract: For realistic simulation it is necessary to thoroughly define and describe light-source characteristics?especially the light-source geometry and the luminous intensity distribution.
TL;DR: With this tool for visualizing and manipulating organ images in three dimensions, surgeons can plan and test their strategies before they get to the operating room.
Abstract: With this tool for visualizing and manipulating organ images in three dimensions, surgeons can plan and test their strategies before they get to the operating room.
TL;DR: Many challenges must be faced before an automatic process-planning system will be practical for individual application, specifically, the recognition and simulation of a part's form features.
Abstract: Many challenges must be faced before an automatic process-planning system will be practical for individual application?specifically, the recognition and simulation of a part's ?form features.?
TL;DR: The design of the user interface management system (UIMS) is discussed within the context of the problems that it is intended to solve and the issues that arise at each level of this continuum.
Abstract: The design of the user interface management system (UIMS) is discussed within the context of the problems that it is intended to solve. The aim is not to review the various forms and strategies that have been proposed and used for UIMS development but rather to clarify the environment of a UIMS. The issues, which relate the services of a UIMS to the applications that it is intended to support, range along a continuum from the keystroke/transaction level, or micro level, to the macro level of integration across an entire application environment. Three examples are presented to illustrate the range of this continuum and the issues that arise at each level.
TL;DR: A new computer graphics technique generates complicated random textures, like those found on natural objects, requiring little data and allowing easy control of textural properties.
Abstract: A new computer graphics technique generates complicated random textures, like those found on natural objects. Requiring little data, it allows easy control of textural properties.
TL;DR: This presentation explains how parametric representations of curved lines and surfaces have evolved into powerful tools for today's computer graphics modeling applications.
Abstract: Overcoming the limitations of polygonal techniques, parametric representations of curved lines and surfaces have evolved into powerful tools for today's computer graphics modeling applications.
TL;DR: The author outlines the major features of an extension to the architecture that will permit the high-speed display and manipulation of multiple, independent, shaded three-dimensional objects represented as a voxel (volume-element) database with gray scale.
Abstract: The features and organization of a hardware architecture that is designed to facilitate the real-time display and manipulation of a single three-dimensional object on a raster-scan video display are briefly summarized. The author then outlines the major features of an extension to the architecture that will permit the high-speed display and manipulation of multiple, independent, shaded three-dimensional objects represented as a voxel (volume-element) database with gray scale. The objective is to provide many useful capabilities at or near video rates facilitating extensive real-time interaction. The architecture is highly modular, permitting a cost tradeoff to be made to achieve a given level of performance. It also includes a great deal of regularity in its structure, making it directly suitable for VLSI implementation. A key feature is that no computational operations more complex than adds, shifts, and comparisons are required in real time. The display characteristics for each object are controlled by a concise object descriptor table, which contains all of the control parameters required to process that object.
TL;DR: The overall feasibility of 3D imaging for intracranial soft tissues depends on three vital areas: the display method, the display options, and the image processing system.
Abstract: The overall feasibility of 3-D imaging for intracranial soft tissues depends on three vital areas: the display method,the display options, and the image processing system.
TL;DR: This tutorial examines the origin and nature of the problem of contention for memory cycles, a problem that impacts the image update performance of every raster graphics system.
Abstract: This tutorial examines the origin and nature of the problem of contention for memory cycles?a problem that impacts the image update performance of every raster graphics system.
TL;DR: Improved techniques of surface interpolation, clipping, and hidden-surface elimination help solve some problems in generating perspective views of digital terrain data.
Abstract: Improved techniques of surface interpolation, clipping, and hidden-surface elimination help solve some problems in generating perspective views of digital terrain data.
TL;DR: Users of interactive CAD systems who are trying to cope with the hidden-surface visualization problem will want to investigate this new algorithm.
Abstract: Users of interactive CAD systems who are trying to cope with the hidden-surface visualization problem will want to investigate this new algorithm.
TL;DR: Properly establishing the relation between linear algebra and geometry makes it easier to obtain the three-by-three orthogonal matrix that describes a specified rotation.
Abstract: Properly establishing the relation between linear algebra and geometry makes it easier to obtain the three-by-three orthogonal matrix that describes a specified rotation.
TL;DR: The author provides a tutorial on Sapphire's screen allocation package, focusing on its icons and user commands.
Abstract: Sapphire (the Screen Allocation Package Providing Helpful Icons and Rectangular Environments) is a powerful window manager running on the PERQ personal workstation. Following some background material, the author provides a tutorial on Sapphire's screen allocation package, focusing on its icons and user commands. The icons in Sapphire are intended to enhance the user's productivity when executing multiple tasks concurrently. Therefore, they present six pieces of information about the process being run, as well as two pieces of information about the status of the window. Thus, the user can easily tell whether the process running in the window has an error or wants attention and what percentage of the task has been completed. The user interface provides full functionality from both the pointing device and the keyboard and is easy for the novice while providing simple and powerful operations for experts. All commands are available from pop-up menus, but accelerators allow the most common commands to be executed with a single button press. The picture in the tracking symbol changes to show the operation that will be performed. This user interface promotes experimentation, since there is always appropriate feedback, and it is always possible to abort an operation once it has been started.
TL;DR: This algorithm exploits basic differential geometry analysis to achieve high speed, low memory usage, reliability, and independence from surface type.
Abstract: This algorithm exploits basic differential geometry analysis to achieve high speed,low memory usage,reliability, and independence from surface type.
TL;DR: This algorithms for Boolean shape operations is relatively fast and simple, based on a triangulation of potentially intersecting faces, and of limited applicability.
Abstract: Most algorithms for Boolean shape operations are complicated, slow, and of limited applicability. This one, based on a triangulation of potentially intersecting faces, is relatively fast and simple.
TL;DR: A geometric modeler for solid objects with complex surfaces is described and two methods based on that theory for combining solid modeling and free-form surface design functions, which are conventionally treated as different disciplines, are presented.
Abstract: In advanced CAD/CAM applications, designers need the capability of modeling solid objects with complex surfaces. This geometric modeler incoroorates new techniques to combine design functions.
TL;DR: In this article, an algorithm for automatically generating from an octree description the data that a computerized numerical control milling machine requires to manufacture a part is presented, which is similar to our work.
Abstract: This preliminary report presents an algorithm for automatically generating from an octree description the data that a computerized numerical control milling machine requires to manufacture a part.
TL;DR: Typography, symbolism, and color are discussed from a corporate identity program perspective, and three case studies, namely, the Xerox Star, the Apple Lisa, and the Intran Metaform system, are examined.
Abstract: The term corporate identity program is well-known in the graphic design field, which has applied the approach to the traditional areas of stationery, vehicle identification, signage, and other forms of complex communication. It is argued that this approach should be extended to the design of screens, especially for high-resolution, iconic, multiwindow interfaces. Typography, symbolism, and color are discussed from this perspective, and three case studies, namely, the Xerox Star, the Apple Lisa, and the Intran Metaform system, are examined.
TL;DR: The principles of good visual design used in advertising can help programmers design effective computer displays that will substantially improve the man-machine interface.
Abstract: The principles of good visual design used in advertising can help programmers design effective computer displays that will substantially improve the man-machine interface.