Computer Gra~hics, 26, 2, JUIV1992 As digital computing costs decline over the next ten years, computer technology's most widespread use will be in consumer applications.The future digital television screen will be a natural visual control center for many new applications, such as normal television entertainment, virtual reality games, home control systems, interactive books, magazines and newsprirt~and telephonic, televideo and data communications.A client-server network environment can exist in which the network is the merged cable-tv/telephone system, the client is a home telecomputer that controls the images seen, and the server is a multi-mdla computer system that is integral to the cable "head-end" or telecommunications "central-office.'1In this paper, I attempt to define the functionality of a telecomputer so that the broadest set of applications is possible.Introduction. "Multi-meda" means the integration of audio, video, graphics and computing into a single digital environment. It promises many new applications that can utilize this combination of techno 10gies.Most people expect the integration to come in next generation personal computers, and many computer companies are working to this end.But for the ordinary consumer, a more likely possibility is that a "telecomputer" will bridge the gap between television and multi-media computing.Think of this "multi-media player" as the digital equivalent of the cable-tv decoder --it will be the consumer's computer.It's central role will continue to be entertainment, such as movies, tv programs and interactive games, but it can also be capable of many functions, including:-textbooks that teach through graphic simulation and animation coupled with audio and videm -media reaieval from databases and libraries -newspaper and magazine retrieval -multiparticipant virtual reality games -digital television entertainment services -digital audio retrieval -media mail -video telephones A low-cost telecomputer in the home is important before authors will invest in writing interactive books.And interactive media services on demand, such as magazines, newspapers, books, encyclopedias, games, and digital audio/video entertainment, need a digital media player in the home before the services can develop. Computer Industry Milestone.The computer industry can benefit enormously by defining telecomputer building blocks so that they can be used in standard multi-media computers.This will ensure compatibility between the consumer and computing worlds --the client and the server.Also, the distribution volumes of consumer electronics can dramatically decrease the cost of computers, enabling portable (tele)computers far more powerful than possible today.Perrrussi{m 10copywlthou!Iectill or pm (It' [hIS nmteritil IS grunted provided thut the copies we nn[ miuk or d]str]bu[ed for direct conmwrcial whuntage.the ACM copyright notice and the title (i the publicwimr and IIS date qrptar.wrd notwc is given th~t copying is by permlssltm ~WIhe A\\twl:itwr Ihr Ctmputirrg Mwhincry, Tn copy otbcrv i.e. or I(I rcpuhllsb.requires ii ICCmd,(~r spccitic parrrissmn 'J"1992 ACM-()-X9791-479-I 92/[)070019 $01.s0

No abstract available.

No abstract available.

The Geometry Engine[1] is a special-purpose VLSI processor for computer graphics. It is a four-component vector, floating-point processor for accomplishing three basic operations in computer graphics: matrix transformations, clipping and mapping to output device coordinates. This paper describes the Geometry Engine and the Geometric Graphics System it composes. It presents the instruction set of the system, its design motivations and the Geometry System architecture.

Andries van DamThe panel will examine the evolution of the professional workstation from a time shared terminal to powerful graphics-based personal computer connected to a resource-sharing local network. The panelists will speculate on the future evolution of both the hardware/software architecture and end user environment.Workstation development at StanfordJames H. ClarkWorkstation development at Stanford is closely linked with graphics, distributed systems and networking. Two distinct systems have evolved over the last 3 years: the SUN system and the IRIS system. The SUN is a low-cost system based upon an efficient MC68000 processor/memory design and a relatively low-performance, high-resolution bit-map display. The IRIS (Integrated Raster Imaging System) is based upon the same MC68000 design, but the graphics part of the system is a modest- to low-cost, high-performance, high-resolution, color or black and white system that uses the Geometry Engine and several other custom IC parts. Both SUN and IRIS interface to the Stanford Ethernet network, and both are being used for distributed systems research, VLSI design stations, and graphics research. In addition, IRIS will probably be used for mechanical CAD research by the mechanical engineering department and in situations where high-performance graphics is important.Improvement Goals for Workstation FacilitiesRobert M. DunnThree major areas of improvement are needed: interaction techniques that are simpler, provide faster reaction, are useful for higher-level inputs, and have user-style-oriented alternatives. The second area is for image rendering based on local capabilities, in varying degrees of image quality as a function of desired “grade of service”. The third area is to provide support to incremental model construction and approximate design evaluation. There must be evaluation techniques that can work on partial models and give one approximate results. Implications of these criteria for workstation architecture will be discussed.The application of network workstations to large-scale engineeringHarvey KriloffThe development of computerized analysis procedures during the last twenty years has been largely oriented toward providing increased analytic function. This has meant that considerations of user access to specific capabilities or ease of use of these mammoth programs are only now becoming user concerns. The emerging new technologies for display, input and their interaction, when applied to the professional workstation, will be playing an increasingly important role in satisfying these concerns. A professional workstation can be used both to improve the efficiency by which data is collected for an existing analysis program and to assist the user in the preparation of data for a formal presentation or report. This performance improvement can be accomplished through the development of user-adapted “macro procedures” for data entry, the execution of processes to check program input data for accuracy and consistency, and workstation assistance in the training of both new and existing users. At the output stage of analysis, the workstation can be used to select and reformat information prepared by the analysis program, explore the interrelationship of results from several different analyses, and derive the data for a succeeding analysis in an iterative design mode.At Boeing Computer Services, we have been exploring the benefits realized by the development of such a workstation when applied to the field of structural engineering. An interaction-rich workstation with a human-engineered executive that controls and integrates the user interface, connected to our national network of IBM, CDC and CRAY computers with a broad variety of engineering software, supplies the engineer with a full range of tools for analysis, data preparation, report writing and data relationship exploration that are only beginning to be appreciated. In the next few years it is expected that this workstation (distributed) methodology for doing engineering and other quantitative professional functions will radically change the way these analytical processes are performed.Personal Workstations in a Local NetworkDavid NelsonFor many applications, personal workstations provide a superior form of computing compared to timesharing. The requirements of workstations, however, go well beyond the facilities provided by the local computer; they must include the equivalent advantages of timesharing such as user-to-user communications, shared programs and data files, shared peripherals, etc. The preferred way to implement these functions is to interconnect all workstations by means of a high-speed local network, controlled by a distributed operating system which provides transparent access to all network resources through a network-wide virtual memory system. Additional workstation functions such as large virtual address space and a concurrent multiple-window display system significantly increase user productivity. A high resolution bit-map display system with hardware support for dynamics is an essential component. For the future we look towards both significant cost reductions and improvement in performance, as well as significantly higher level software to better implement the user-computer interface.

System design is undergoing radical changes that are significant both for the graphics community and for other design communities in which the principal hardware resources are those obtained via catalogues of parts. The drive to reduce system costs forces us to design at the lowest level possible, i.e., on silicon; only in this way can we reduce the number of packaged components, thereby reducing the number of interconnecting wires, board space and power requirements. This, in turn, presents a system design dilemma. The large cost of designing silicon systems, i.e. VLSI, conflicts with the need to design them to reduce cost. As a result, novel new design aids are being devised that actually make integrated system design easier than conventional system design; integrated systems can be thoroughly simulated because simple models of them exist at every level of representation.

Accompanying the rapid development of integrated circuit fabrication technology has been a parallel, but slower, development of IC design techniques and systems. Recent approaches to IC design enable individual designers to consider developing their own VLSI circuits. Such capability may open the door to a more varied set of system designs than could previously be considered in most design environments.

An algorithm for rendering shaded pictures of parametric curved surfaces is presented. The algorithm recursively subdivides each surface element on the basis of its screen-space parametric curvature until it is sufficiently close to bilinear to be scan-converted by conventional polygon rendering techniques. The mathematical basis chosen to carry out the subdivision process yields the curvature criterion as a coefficient so that the tests for termination of the subdivision process are extremely simple. In addition, a surface is subdivided only in the parametric direction in which its curvature deviates from the tolerance. The algorithm incorporates a very simple solution to the problem of separations between sibling subpatches.

The research described in this paper addresses the problems associated with the design of systems for efficiently producing computer-generated pictures and picture sequences of very complex, three-dimensional environments. The thesis of the research is that the geometric structure inherent in the definition of the shapes of three-dimensional objects and environments must be used not just to define their relative motion and placement but also to assist in solving many other problems of systems for producing pictures by computer.The implications are that by using an extension of traditional structure information, or a geometric hierarchy, five significant improvements to current techniques are possible. First, the range of complexity of an environment is greatly increased while the visible complexity of any given scene is kept within a fixed upper limit. Second, a meaningful way is provided to vary the amount of detail presented in a scene both according to the screen area occupied by the objects in the scene and according to camera and object motions. Third, by using the geometric hierarchy, "clipping" becomes a very fast logarithmic search for the resolvable parts of the environment within the field-of-view. Fourth, by using this positional hierarchy in conjunction with a storage hierarchy of the sort used in virtual memory computing systems, frame-to-frame coherence and clipping define a graphical "working set", or fraction of the total structure that should be present in primary store for immediate access by the visible-surface algorithms. Finally, the proposed structural framework suggests a new recursive descent visible-surface algorithm in which the computation time grows almost linearly with a scene's visible complexity rather than as a worse than linear function of its object-space complexity.

The film accompanied by this paper illustrates an experimental system for real-time Computer-Aided Geometric Design of three-dimensional parametric surfaces. A detailed description of the system is given in another paper by the author(1). Its principle features are that it operates in real-time, all geometric interaction with the surfaces is accomplished with a 3-D Wand, the surfaces are viewed in 3-D using a head-mounted display, and the surfaces are mathematically represented using parametric spline surface patches.The two principle computing components of the system are a PDP-10 computer and an LDS-1 display computer. The PDP-10 acts as a host to the LDS-1. Its main tasks each 1/30 second are to compute the 3-D Wand and head-mounted display positions and to incrementally update the geometries of the surface patches being designed by the user. During the same time period, the LDS-1 loads its digital matrix multiplier with the room-to-head transformation matrix provided to it by the PDP-10, displays on the head-mounted display's CRT's a line drawn rendering of all of the parametric surface patches that are within the 40 degree field-of-view of the display and displays a small cube to represent the current position of the Wand.The user of the system initiates a design sequence by selecting a patch description file from the PDP-10's file system. He then puts on the head-mounted display and uses the 3-D Wand with its control buttons to grasp the patches, which appear to float before him in the room, and make appropriate changes to their geometry. After a design sequence he may save the new surfaces on the PDP-10 file system and select certain views of the surfaces to be rendered as a continuous-tone shaded picture with hidden-surfaces removed.The first part of the film described here shows the system in real-time operation. During this part, several free-form surfaces are manipulated as the camera records the action on a line-drawing monitor. The second part of the film illustrates a continuous-tone, shaded rendering of a design sequence. The continuous-tone rendering was produced "off-line" using pertinent viewpoint information that was saved during the design sequence. The final few minutes of the film depict the construction of a Klein-Bottle.