bluuebunny/crossref_metadata_2025 huggingface dataset:
Graphics standards for three-dimensional modelling
Authors: Sabin Malcolm
Published: November 2005

Much effort has been spent in defining a standard call interface for a library of routines with display primitives embedded in a three-dimensional space. This paper argues that this is now an inappropriate target. There is too much diversity in the three-dimensional things we want to draw and in the kinds of picture we want to draw of them for any single standard to be both broadly acceptable and specifically useful.

If the decision is made to go for a set of specialized standards for wire frame and for rendered graphics for data presentation, for sculptured surfaces and for object models, it becomes apparent that far more can be gained from a higher level standard, at the data presentation or object modelling level.

In the object modelling community, at least, there is indeed work toward such a standard based on the IGES proposals. This has very few concepts in common with the graphics standard effort, and it is not clear at present what contribution the graphics community has to make in this area.

The suggestion made here is that there may well be a number of paragraphs or sections common to more than one of the graphics-related and higher level standards. One such is the coordinate transformation (the dreaded 4 × 4 matrix). Its definition and its use both for modelling and viewing concepts are suggested which resolve some of the black art associated with transformation in the past. These could become the conceptual basis for a short simple standard in this area.
An inversion algorithm for geometric models
Authors: Mäntylä Martti
Published: November 2005

Instead of storing boundary models of solids directly into a data base, it would be advantageous to map them first into a simpler form. This approach calls for a procedure called in this paper the
inversion algorithm
of a geometric model. We present and analyze an inversion algorithm which constructs a sequence of Euler Operators capable of creating a given boundary representation. The algorithm is completely based on the use of Euler Operators enabling us to keep the algorithm simple and to hide implementation and data structure details.
Presidents' forum
Authors: Feddersen Donald , Linsalata Ralph T. , Preuss Peter , Spann Richard N. , Machover Carl
Published: November 2005

Computer Graphics has been an integral part of the computer environment since the mid-1950's with origins in military, academic and industrial applications.

Presidents of several leading computer graphics companies will discuss some of the issues they see facing this dynamic industry. One president believes that the 1980's will belong to the systems integrators because of the rapid rate of change in both technology and the competitive environment. Vertical integration will not be a successful strategy for the 1980's.

Another president is concerned that industry research analysts are misusing the term “CAD/CAM” and that, in fact, most of today's CAD/CAM systems are simply productive drafting systems. He is concerned about the confusion between realistic pictures and solid modelling and about the proper mix of functionality and interactivity.

Still another president believes the crucial issues in computer graphics are those that concern users; those that have access to the tools and those of future development of hardware and software to meet their needs. He suggests that only about one to five percent of the potential users have adopted computer graphics. He is concerned about providing increased access to computer graphics facilities and about removing the widespread psychological barrier of “I can't use the computer to do what I want!”.

Other current issues will also be addressed.
The graphics CAD/CAM industry(Panel Session)
Authors: Adler Frederick R. , Kurlack Thomas P. , McNay Joseph C. , Reichenbach Margaret A. , Spann Richard N.
Published: November 2005

Richard N. Spann

Companies supplying graphics CAD/CAM components and systems form an important high technology business segment. Panelists representing four financial perspectives will discuss market entry, financing, segment performance and shareholder's expectations. Development of the graphics CAD/CAM industry in the 80's will be the unifying theme.
The Geometry Engine
Authors: Clark James H.
Published: November 2005

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.
A contour display generation algorithm for VLSI implementation
Authors: Zyda Michael J.
Published: November 2005

Recent articles have discussed the current trend towards designing raster graphics algorithms into VLSI chips. The purpose of these design efforts is to capture some of the real-time animation capability found in vector graphics systems. Currently, real-time vector graphics animation is limited primarily to operations involving coordinate transformations. In order to enhance this animation capability, frequently encountered vector graphics algorithms that require the high speed, parallel computation capability of VLSI must be identified. Real-time contour display generation from grid data is one such algorithm. This paper describes the specifics of a contour display generation algorithm, the architectural framework of a processor that performs this algorithm and the architectural requirements of such a processor.

The contouring algorithm is based on a data structure, the contouring tree, whose regularity and amenability for parallel computation make it an ideal candidate for VLSI. The architectural framework for a contouring processor chip that performs this algorithm for the real-time environment of interactive graphics is discussed, particularly the issues of memory size and data distribution. A model of the contouring process is created in order to determine the necessary physical parameters of the contouring processor in this architectural framework. Conclusions are drawn concerning the feasibility of producing a VLSI chip that performs this contouring algorithm.
Special purpose automatic programming for hidden surface elimination
Authors: Goad Chris
Published: November 2005

In many applications of three dimensional computer graphics, the appearance of the same scene must be computed repeatedly for many different positions of the viewer. This paper concerns a scheme for exploiting this property of an application for the purpose of improving the efficiency of the hidden surface computation. The scheme involves a kind of automatic programming: for each scene to be considered, a different special purpose program is automatically constructed. The special purpose program then takes the position of the viewer as input, and generates a suitable description of the scene with hidden surfaces removed as output. Since the special purpose program has a very limited task to perform - it is adapted to handling just one scene - it can be much faster than any general purpose algorithm would be for the same scene. The paper describes a method by which special purpose programs for hidden surface elimination can be constructed in a fully automatic manner. The method has been implemented, and results of experiments are given.
Context-sensitive, graphic presentation of information
Authors: Friedell Mark , Barnett Jane , Kramlich David
Published: November 2005

We begin by reviewing spatial data management—the technique of accessing and organizing information via its graphical representation in an organized spatial framework.

We describe an operational prototype system that exceeds the capabilities of other spatial data management systems in two ways: (1) the graphical presentation of data is tailored to the user's identity, task, and database query; and (2) the system has the capacity for large databases. These capabilities are possible because the system dynamically generates its graphics environment.

Our technique for dynamically generating the graphics environment relies on modeling of user context, semantic modeling of the underlying database, and direct use of knowledge about design layout and the utility of pictures. We briefly describe our current research efforts to extend this knowledge-based approach to automatic graphics environment synthesis.

A videotape demonstrating the system accompanies this paper.
MAPQUERY
Authors: Frank André
Published: November 2005

The storage of geographical data is a growing type of application within data processing.

Users want to retrieve parts of the data stored and to have them shown in graphical form. They need an easy and flexible query language to select the data needed and to describe the form of representation. The existing query languages do not suit this purpose without amendments. This paper presents a proposal for adaptation and gives some examples for query formulation. Moreover, it discusses the special problems of graphical input and output.
3D Galatea
Authors: MacKay Steven A. , Sayre Richard E. , Potel Michael J.
Published: November 2005

We describe an interactive graphics system for the entry of three-dimensional moving points from multiple perspective views. This work represents a major extension of Galatea, our system for graphics-assisted 2D motion analysis. 3D Galatea permits reconstruction of 3D time-dependent positions from 2D entries in two or more perspective views.

The system supports a general approach for calibrating perspective views. This method, based on work of Sutherland, uses a known 3D reference object to calibrate completely arbitrary perspective projections. A somewhat restricted class of perspective views may be calibrated without an explicit calibration object using another approach developed from photogrammety.

In 2D Galatea, we have used an animated graphics overlay onto the source image to give the analyst feedback regarding current and previous data entries. This capability is extended in 3D Galatea by overlaying auxiliary lines, which are the backprojections of previous 2D entries from one view into other views. This concept amounts to a fourth interpretation of the well-known Roberts homogeneous matrix equation describing perspective projections of 3D space into a 2D image. The auxiliary line is useful in locating a point which is obscured in one of the images, or in determining the correspondence of projected points as seen in different views, which may be ambiguous or easily confused.
Graphic input interaction techniques(Panel Session)
Authors: Thomas James J.
Published: November 2005

In the last decade most research and development in computer graphics has been in the output side. Input devices and techniques for communicating with graphic systems are now also becoming active research topics. To communicate the state-of-the-art and to identify the key research issues, SIGGRAPH sponsored a workshop on graphics interaction input techniques in June, 1982. The topics to be discussed include tools for building user interfaces, recent successes using those tools, human factors, generic interaction types, interaction techniques for raster systems and style-independent interaction techniques. The workshop will be summarized with an address on the current state-of-the-art and identification of the major research issues. In addition, selected participants will be asked to address the primary research issues.
Scanline rendering of parametric surfaces
Authors: Schweitzer Dino , Cobb Elizabeth S.
Published: November 2005

A scanline algorithm is described which renders bicubic patches directly from the parametric description without producing a polygonal approximation. The algorithm is partially based on earlier work by Whitted. A primitive object, called a “curved-edge polygon”, is defined, and an algorithm for breaking down a bicubic patch into the primitive objects is described. A general surface intersection method is employed to provide a robust silhouette edge detector. Shades are computed by calculating a cubic approximation to the normal surface and performing either a cubic or a linear interpolation of the bounding edge normals across the scanline. Subdivision of parametric surfaces is used to reduce the complexity of the surfaces being rendered, providing dramatic improvement in the results of both the silhouette detector and the shading methods.
Business graphics(Panel Session)
Authors: Jarett Irwin , Russell Jack , Johnson Howard , Thompson John , Luther David
Published: November 2005

Much has been written about the explosive growth occurring and forecast for business graphics. Users and vendors alike are excited by these prospects. But, what is business graphics? Is it narrowly confined to slide making? Some with a broad view have suggested it is an extension of a management information system. Users search through journals and marketing literature eager to prove a salesman's claim that “a pretty color picture is really worth a thousand words” or at least several pages of numbers in a computer printout. Vendors seek the clues to developing a product strategy that will allow them to cash in on the forecasted shipments. One study [1] indicated 58,000 graphic terminals will be used in business graphics applications in 1986 sales, including computer graphics—capable personal computers, and dedicated computer graphics systems.

This panel will present the thoughts and views of four business graphics practitioners—one associated with a large computer company, another a user from a large industrial concern, the third associated with an independent software company and the last, an industry consultant.
Computer animation with scripts and actors
Authors: Reynolds Craig W.
Published: November 2005

A technique and philosophy for controlling computer animation is discussed. Using the Actor/Scriptor Animation System (ASAS) a sequence is described by the animator as a formal written SCRIPT, which is in fact a program in an animation/graphic language. Getting the desired animation is then equivalent to “debugging” the script. Typical images manipulated with ASAS are synthetic, 3D perspective, color, shaded images. However, the animation control techniques are independent of the underlying software and hardware of the display system, so apply to other types (still, B&W, 2D, line drawing ...). Dynamic (and static) graphics are based on a set of geometric object data types and a set of geometric operators on these types. Both sets are extensible. The operators are applied to the objects under the control of modular animated program structures. These structures (called
actor
s) allow parallelism, independence, and optionally, synchronization, so that they can render the full range of the time sequencing of events.
Actor
s are the embodiment of imaginary players in a simulated movie. A type of animated number can be used to drive geometric expressions (nested geometrical operators) with dynamic parameters to produce animated objects. Ideas from programming styles used in current Artificial Intelligence research inspired the design of ASAS, which is in fact an extension to the Lisp programming environment. ASAS was developed in an academic research environment and made the transition to the “real world” of commercial motion graphics production.
Color image quantization for frame buffer display
Authors: Heckbert Paul
Published: November 2005

Algorithms for adaptive, tapered quantization of color images are described. The research is motivated by the desire to display high-quality reproductions of color images with small frame buffers. It is demonstrated that many color images which would normally require a frame buffer having 15 bits per pixel can be quantized to 8 or fewer bits per pixel with little subjective degradation. In most cases, the resulting images look significantly better than those made with uniform quantization.

The color image quantization task is broken into four phases:

1) Sampling the original image for color statistics

2) Choosing a colormap based on the color statistics

3) Mapping original colors to their nearest neighbors in the colormap

4) Quantizing and redrawing the original image (with optional dither).

Several algorithms for each of phases 2-4 are described, and images created by each given.
The role of videotex (Panel Session)
Authors: Botten Brian , Norton John , Schneider Lois , Tompa Frank W. , Godfrey David , Dam Andries van
Published: November 2005

Frank W. Tompa

Interactive videotex systems may soon emerge as a principal information, entertainment and communications medium relying heavily on computer graphics. Until now, much has been written about the image presentation and data facilities of the several current systems, but videotex literature and research is unexpectedly far removed from mainstream graphics audiences. The purpose of this panel session is therefore to narrow the gap.

In outline, the panel session includes an introduction to videotex, followed by several short presentations covering videotex graphics, experience, alternatives, and prospects.

Brian Botten

David Godfrey

John Norton

Lois Schneider

Andries van Dam
A device independent graphics imaging model for use with raster devices
Authors: Warnock John , Wyatt Douglas K.
Published: November 2005

In building graphic systems for use with raster devices, it is difficult to develop an intuitive, device independent model of the imaging process, and to preserve that model over a variety of device implementations. This paper describes an imaging model and an associated implementation strategy that:

1. Integrates scanned images, text, and synthetically generated graphics into a uniform device independent metaphor;

2. Isolates the device dependent portions of the implementation to a small set of primitives, thereby minimizing the implementation cost for additional devices;

3. Has been implemented for binary, grey-scale, and full color raster display systems, and for high resolution black and white printers and color raster printers.
A visible polygon reconstruction algorithm
Authors: Sechrest Stuart , Greenberg Donald P.
Published: November 2005

An algorithm for determining visible lines or visible surfaces in polygonal form, at object resolution, is presented. The original scene must consist of non-intersecting planar polygons. The procedure relies on image coherence, since the sampling is dependent on the complexity of the image. The reconstruction method is based on an elaborate data structure, which allows the polygonal output to be easily obtained. The polygonal output is useful for smooth shaded or textured images, as well as the for creation of shadows.
Contour filling in raster graphics
Authors: Pavlidis Theo
Published: November 2005

The paper discusses algorithms for filling contours in raster graphics. Its major feature is the use of the line adjacency graph for the contour in order to fill correctly nonconvex and multiply connected regions, while starting from a “seed.” Because the same graph is used for a “parity check” filling algorithm, the two types of algorithms can be combined into one. This combination is useful for either finding a seed through a parity check, or for resolving ambiguities in parity on the basis of connectivity.
Parallel processing image synthesis and anti-aliasing
Authors: Weinberg Richard
Published: November 2005

The continuing evolution of microelectronics provides the tools for developing new methods of synthesizing digital images by utilizing parallel processing architectures which hold the promise of reliability, flexibility and low cost. Beginning with the earliest real-time flight simulators, parallel processing architectures for image synthesis have been built, but "anti-aliasing" remains a problem. A parallel processing architecture is described and simulated which consists of a serial chain of processors which produces as output a depth sorted list of those objects which are at least potentially visible at each pixel. The lists are then filtered to provide the final shading at each pixel.
A VLSI architecture for updating raster-scan displays
Authors: Gupta Satish , Sproull Robert F. , Sutherland Ivan E.
Published: November 2005

Interactive use of a display requires the capability to update the display rapidly. This paper describes an on-going project at Carnegie-Mellon University in which we are designing a frame buffer raster-scan display system which has the high performance typically required for interactive display applications. The system is intended to be a display for personal computers, computer generated graphic images, and image processing applications. Built using smart VLSI memory chips, the system will use parallel processing techniques to provide high performance.
A system design revolution (Panel Session)
Authors: Clark James H. , Sproull Robert
Published: November 2005

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.

By providing the system designer with lower-level design primitives, significant new architectures, such as the Geometry Engine and Image Memory Processor, will be the result. Semiconductor companies cannot make system design decisions for every area of application; only the system designer understands the application area well enough to make the correct decisions. The traditional semiconductor industry must make a transition from offering packaged system building blocks to offering fabrication services to the designers who know how to design systems.
Effective use of color in computer graphics
Authors: Truckenbrod Joan R.
Published: November 2005

Color is a significant component of computer aided visualization of information, concepts and ideas. The use of color in all applications of computer graphics enhances the image, clarifies the information presented, and helps distinguish features that are obscure in black and white pictures. Color is used to differentiate elements in the diagrams so that the comparative information is read and understood rapidly and accurately. Color visualization techniques increase the amount of information that can be integrated into the visual message or picture, and thus create layers of information. It is clear that research and discovery can be supported and enhanced by color application, or inhibited by ineffectual use of color. In order to effectively utilize color in the visualization of ideas, information, or concepts, the role of color in various applications must be examined, and the perceptual behavior of color must be delineated. The basic principles of color theory have been discussed to provide a fundamental understanding of the characteristics of color and the manner in which colors interact with one another. Based on these principles, the user will be better able to utilize color in an effective manner relative to specific applications in color graphics.
Tablet-based valuators that provide one, two, or three degrees of freedom
Authors: Evans Kenneth B. , Tanner Peter P. , Wein Marceli
Published: November 2005

The ability of the user of a graphics system to interactively control the motions of 3-D objects enhances his or her spatial perception and comprehension of those objects. This paper describes several logical devices based on the tablet, each particularly suited to control some type of interactive manipulation of 2-D and 3-D objects in real time. The “turntable” and the “stirrer” convert rotary motion of the tablet pen or puck into values for one-axis rotational control; the “rack”, a two-axis device, is used for scaling control; for three-axis rotational control, the tablet-based three-axis trackball is particularly suited.
A methodology for the specification of graphical user interface
Authors: Green Mark
Published: November 2005

We present a methodology for the design of interactive user interfaces. This methodology provides the designer with a number of steps to be followed in the design of a user interface. Examples of a formal notation for describing user interfaces are presented. This methodology also provides the designer with a number of techniques for evaluating his design. We present a list of desirable properties for a user interface design methodology. Our design methodology has all of these properties.
Gaze-orchestrated dynamic windows
Authors: Bolt Richard A.
Published: November 2005

Consider a large-format display before the user, bearing a multiplicity of “windows,” like little movies, the majority dynamic and in color. There are upwards of 20 windows, say, more than a person can ordinarily absorb at once. Some of the windows come and go, reflecting their nature as direct TV linkages into real-time, real-world events. Others are non-real-time, some dynamic, others static but capable of jumping into motion.

Such an ensemble of information inputs reflects the managerial world of the top-level executive of the not too distant electronic future: a world of brevity, fragmentation, variety, above all one of an overwhelming onslaught of events.

The multiplicity and simultaneity of such a display situation ordinarily would make coping with it untenable. The intent of the reported research is to introduce order and control, through the creation of a dynamic,
gaze-interactive
interface.

Making the behavior and reactivity of the “windows” contingent upon measured eyemovements - the point-of-regard of the observer - aims both to help the observer to cope with the onslaught of events on the one hand, yet enable on the other hand continuing close contact with that everchanging ensemble.

A simulation of such a world is described and demonstrated in the composite medium of computer, videodisc, and video special effects. Eye-tracking technology, integrated with speech and manual inputs, controls the display's visual dynamics, and orchestrates its sound accompaniments. All elements are combined to form a testbed for the conception generally, and to explore the associated human factors and stagecraft.
An application of color graphics to the display of surface curvature
Authors: Dill John C.
Published: November 2005

In developing a mathematical representation for a surface, designers currently must use line drawing graphics to examine the curvature of a line in a plane, a two-dimensional analysis. By combining a result from differential geometry with the use of color raster graphics, the method described in this paper provides a means for the designer to examine surface curvature, a three-dimensional analysis. In particular, a formulation for the Gaussian and average curvatures is given and it is shown how these indicate the presence or absence of protrusions, hollows, etc. in a surface, i.e., how, where, and by how much the surface curves.

Showing a fourth variable, curvature in this case, over a three-dimensional surface is difficult, if not impossible with traditional line drawing computer graphics. The method described solves this problem by using color as a fourth dimension. Examples are given, including both known shapes (torus) and automotive parts (hood, fender).
An integrated system for creating and presenting complex computer-based documents
Authors: Feiner Steven , Nagy Sandor , Van Dam Andries
Published: November 2005

An experimental system is described for the design, development, and presentation of computer-based documents that combine pictures and text on a high-resolution raster color display. Such documents can be used, for example, for maintenance and repair tasks or computer-aided instruction.

Documents
are directed graphs whose nodes we refer to as
pages
, in analogy to the pages of a paper book. A page includes a set of simultaneously displayed pictures, actions (procedures and processes) triggered when the page is accessed or when pickable picture elements on it are selected, and indexing information. Pages may be nested arbitrarily deeply in
chapters
that serve much the same organizing function as those of conventional books.

The system is comprised of separate programs for laying out and drawing pictures, for graphically specifying the contents of pages, chapters, and their interconnections, and for displaying the document for user interaction.

Examples are given from a prototype document for the maintenance and repair of computerized numerical control equipment. Emphasis was placed on designing actions for simple realtime animation (both by color table techniques and by transforming named primitives and manipulating their attributes), and for finding one's way around the document (displays include: a “timeline” of recently visited pages, immediate predecessor and successor pages, sibling pages and their interconnections, and those pages satisfying key-word retrieval requests).
Towards a laboratory instrument for motion analysis
Authors: Baecker Ronald , Miller David , Reeves William
Published: November 2005

Motion analysis
is the systematic and usually quantitative study of the movements of humans, animals, organisms, cells, or other entities as recorded on movie film or video tape. Despite the utility of computer-aided motion analysis to many biological, social, and physical sciences, its role has been limited because it is so time-consuming and so expensive. Automated techniques can only be used on real images in very special cases; interactive techniques have involved laborious
frame by frame
operations.

In recent years, Futrelle and Potel have revolutionized the process of interactive motion analysis by demonstrating how to
digitize entire motions with a single sketch
rather than with a sequence of operations on each constituent frame. However, their GALA-TEA system is applicable only to film and not to video tape records, and consists of equipment which cannot easily be engineered into a reliable and mass-producible laboratory instrument.

The paper describes a prototype laboratory instrument for the interactive motion analysis of video tape records. The prototype includes a host PDP 11/45 computer, an experimental display processor called SPIWRIT, and a microprocessor-controlled video disk. SPIWRIT generates a computer-animated video representation of the phenomenon being analysed, and superimposes it on the actual video record being streamed from the video disk. SPIWRIT's bit-slice microprogrammable display processor produces true animation on a colour raster display by decoding segmented display file images into alternate halves of a double frame buffer.
Austere C
3
graphics
Authors: Todd Robert , DeShazo Patrick
Published: November 2005

The MITRE Corporation, a not for profit Federal Contract Research Center (FCRC), has been involved in Command, Control and Communications (C
3
) Systems Engineering for the past twenty years. MITRE's program in support of the Defense Communications Agency (DCA)/Command and Control Technical Center (CCTC) involves planning and systems engineering for the Worldwide Military Command and Control System (WWMCCS). Included as components of the WWMCCS are survivable command centers such as the National Emergency Airborne Command Post (NEACP). MITRE has been involved in the system engineering functions of the NEACP Automatic Data Processing (ADP) system and other austere command posts. A portion of MITRE's overall system engineering activities included the design of an austere graphics capability for the NEACP ADP system. This paper explains the constraints, problems, needs and solutions to this engineering project.

The goal of this paper focuses on selecting a suite of graphics capabilities that can be implemented in an austere computer environment and which can support generic C
3
ADP graphics requirements. This paper also focuses on highlighting graphics capabilities that satisfy C
3
display needs but are realizable in an austere computer system.
Two aspects of domain designing
Authors: Rockwood Alyn P. , Jensen Thomas W.
Published: November 2005

In 1965, Shepard introduced a general interpolation formula for arbitrarily spaced data over any finite dimensional Euclidean space. The deficiencies in his initial results have been corrected and later derivations have been widely applied to surface fitting problems in aviation design and geology.

This paper describes a new research direction in Shepard's method and a new application to computer graphics. In the first, the convex weighting functions are generalized by the creation of a user-defined mathematical domain which is independent of the surface. In the second, the original formula is applied to blend mapping projections for aviation visual simulation and an algorithm for rapid evaluation is presented.
ANSI X3H3 Technical Committee on Computer Graphics (Panel Discussion)
Authors: Puk Richard , Reed Ted , Skall Mark , Wright Tom , Bono Peter
Published: November 2005

Several members of the American National Standards Institute (ANSI) Technical Committee X3H3 on Computer Graphics will present current issues of the standardization effort. The focus of the discussion will be the technical content of these issues.

The purpose of the panel discussion is to encourage technical dialogue between X3H3 participants and interested parties outside of X3H3. To that end, the presentations will describe major areas of concern, avenues of attack, and proposed solutions.
A software test-bed for the development of 3-D raster graphics systems
Authors: Whitted Turner , Weimer David M.
Published: November 2005

We describe a set of utility routines for 3-D shaded display which allow us to create raster scan display systems for various experimental and production applications. The principal feature of this system is a flexible scan conversion processor that can simultaneously manage several different object types.

Communications between the scan conversion routine and processes which follow it in the display pipeline can be routed through a structure called a “span buffer” which retains some of the high resolution, three dimensional data of the object description and at the same time has the characteristics of a run length encoded image.
3D graphics and the wave theory
Authors: Moravec Hans P.
Published: November 2005

A continuing trend in computer representation of three dimensional synthetic scenes is the ever more accurate modelling of complex illumination effects. Such effects provide cues necessary for a convincing illusion of reality. The best current methods simulate multiple specular reflections and refractions, but handle at most one scattering bounce per light ray. They cannot accurately simulate diffuse light sources, nor indirect lighting via scattering media, without prohibitive increases in the already very large computing costs.

Conventional methods depend implicitly on a
particle
model; light propagates in straight and conceptually infinitely thin rays. This paper argues that a
wave
model has important computational advantages for the complex situations. In this approach, light is represented by wave fronts which are stored as two dimensional arrays of complex numbers.

The propagation of such a front can be simulated by a linear transformation. Several advantages accrue. Propagations in a direction orthogonal to the plane of a front are convolutions which can be done by FFT in O(
n
log
n
) time rather than the

n
2

time for a similar operation using rays. A typical speedup is about 10,000. The wavelength of the illumination sets a resolution limit which prevents unnecessary computation of elements smaller than will be visible. The generated wavefronts contain multiplicities of views of the scene, which can be individually extracted by passing them through different simulated lenses. Lastly the wavefront calculations are ideally suited for implementation on available array processors, which provide more cost effective calculation for this task than general purpose computers.

The wave method eliminates the aliasing problem; the wavefronts are inherently spatially filtered, but substitutes diffraction effects and depth of focus limitations in its stead.
A lens and aperture camera model for synthetic image generation
Authors: Potmesil Michael , Chakravarty Indranil
Published: November 2005

This paper extends the traditional pin-hole camera projection geometry, used in computer graphics, to a more realistic camera model which approximates the effects of a lens and an aperture function of an actual camera. This model allows the generation of synthetic images which have a depth of field, can be focused on an arbitrary plane, and also permits selective modeling of certain optical characteristics of a lens. The model can be expanded to include motion blur and special effect filters. These capabilities provide additional tools for highlighting important areas of a scene and for portraying certain physical characteristics of an object in an image.
Curved surfaces and coherence for non-penetrating rigid body simulation
Authors: Baraff David
Published: November 2005

A formulation for the contact forces between curved surfaces in resting (non-colliding) contact is presented. In contrast to previous formulations, constraints on the allowable tangential movement between contacting surfaces are not required. Surfaces are restricted to be twice-differentiable surfaces without boundary. Only finitely many contact points between surfaces are allowed; however, the surfaces need not be convex. The formulation yields the contact forces between curved surfaces and polyhedra as well. Algorithms for performing collision detection during simulation on bodies composed of both polyhedra and strictly convex curved surfaces are also presented. The collision detection algorithms exploit the geometric coherence between successive time steps of the simulation to achieve efficient running times.
Dynamic simulation of autonomous legged locomotion
Authors: McKenna Michael , Zeltzer David
Published: November 2005

Accurate simulation of Newtonian mechanics is essential for simulating realistic motion of joined figures. Dynamic simulation requires, however, a large amount of computation when compared to kinematic methods, and the control of dynamic figures can be quite complex. We have implemented an efficient forward dynamic simulation algorithm for articulated figures which has a computational complexity linear in the number of joints. In addition, we present a strategy for the coordination of the locomotion of a six-legged figure - a simulated insect - which has two main components: a gait controller which sequences stepping, and motor programs which control motions of the figure by the application of forces. The simulation is capable of generating gait patterns and walking phenomena observed in nature, and our simulated insect can negotiate planar and uneven terrain in a realistic manner. The motor program techniques should be generally applicable to other control problems.
Geometric collisions for time-dependent parametric surfaces
Authors: Von Herzen Brian , Barr Alan H. , Zatz Harold R.
Published: November 2005

We develop an algorithm to detect geometric collisions between pairs of time-dependent parametric surfaces. The algorithm works on surfaces that are continuous and have bounded derivatives, and includes objects that move or deform as a function of time. The algorithm numerically solves for the parametric values corresponding to coincident points and near-misses between the surfaces of two parametric functions.Upper bounds on the parametric derivatives make it possible to guarantee the successful detection of collisions and near-misses; we describe a method to find the derivative bounds for many surface types. To compute collisions between new types of surfaces, the mathematical collision analysis is needed only once per surface type, rather than analyzing for each pair of surface types.The algorithm is hierarchical, first finding potential collisions over large volumes, and then refining the solution to smaller volumes. The user may specify the desired accuracy of the solution. A C-code implementation is described, with results for several non-bicubic and bicubic time-dependent parametric functions. An animation of the collision computation demonstrates collisions between complex parametric functions.
Particle transport and image synthesis
Authors: Arvo James , Kirk David
Published: November 2005

The rendering equation is similar to the linear Boltzmann equation which has been widely studied in physics and nuclear engineering. Consequently, many of the powerful techniques which have been developed in these fields can be applied to problems in image synthesis. In this paper we adapt several statistical techniques commonly used in neutron transport to stochastic ray tracing and, more generally, to Monte Carlo solution of the rendering equation. First, we describe a technique known as
Russian roulette
which can be used to terminate the recursive tracing of rays without introducing statistical bias. We also examine the practice of creating ray trees in classical ray tracing in the light of a well-known technique in particle transport known as
splitting
. We show that neither ray trees nor paths as described in [10] constitute an optimal sampling plan in themselves and that a hybrid may be more efficient.
Hidden curve removal for free form surfaces
Authors: Elber Gershon , Cohen Elaine
Published: November 2005

This paper describes a hidden curve algorithm specifically designed for sculptured surfaces. A technique is described to extract the visible curves for a given scene without the need to approximate the surface by polygons. This algorithm produces higher quality results than polygon based algorithms, as most of the output set has an exact representation. Surface coherence is used to speed up the process. Although designed for sculptured surfaces, this algorithm is also suitable for polygonal data.
An efficient radiosity solution for bump texture generation
Authors: Chen Hong , Wu En-Hua
Published: November 2005

The development of global illumination and texture generation makes it possible to produce the most realistic images. However, it is still difficult or deficient so far to simulate bump texture effects while the interreflection of light being modeled by the present ray tracing or radiosity methods. A method of bump texture generation, being incorporated into the process of radiosity solution, is presented in the paper. The method is characterized by introduction of a
perturbed radiosity map
, established in the context of either progressive radiosity or standard radiosity solution. To calculate the perturbed radiosity, a concept of
perturbed form-factors
is proposed, and the algorithms for evaluating the perturbed form-factors are also given. As a result, a bilinear-interpolation shading scheme for perturbed surfaces is provided, and the texturing method is easily added to a newly improved solution of progressive refinement radiosity for non-diffuse environment.
Adaptive radiosity textures for bidirectional ray tracing
Authors: Heckbert Paul S.
Published: November 2005

We present a rendering method designed to provide accurate, general simulation of global illumination for realistic image synthesis. Separating surface interaction into diffuse plus specular, we compute the specular component on the fly, as in ray tracing, and store the diffuse component (the radiosity) for later-reuse, similar to a radiosity algorithm. Radiosities are stored in
adaptive radiosity textures (rexes
)
1
that record the pattern of light and shadow on every diffuse surface in the scene. They adaptively subdivide themselves to the appropriate level of detail for the picture being made, resolving sharp shadow edges automatically.We use a three-pass, bidirectional ray tracing algorithm that traces rays from both the lights and the eye. The "size pass" records visibility information on diffuse surfaces; the "light pass" progressively traces rays from lights and bright surfaces to deposit photons on diffuse surfaces to construct the radiosity textures; and the "eye pass" traces rays from the eye, collecting light from diffuse surfaces to make a picture.
Project GROPEHaptic displays for scientific visualization
Authors: Brooks Frederick P. , Ouh-Young Ming , Batter James J. , Jerome Kilpatrick P.
Published: November 2005

We began in 1967 a project to develop a haptic+display for 6-D force fields of interacting protein molecules. We approached it in four stages: a 2-D system, a 3-D system tested with a simple task, a 6-D system tested with a simple task, and a full 6-D molecular docking system, our initial goal. This paper summarizes the entire project---the four systems, the evaluation experiments, the results, and our observations. The molecular docking system results are new.Our principal conclusions are:• Haptic display as an augmentation to visual display can improve perception and understanding both of force fields and of world models populated with impenetrable objects.• Whereas man-machine systems can outperform computer-only systems by orders of magnitude on some problems, haptic-augmented interactive systems seem to give about a two-fold performance improvement over purely graphical interactive systems. Better technology may give somewhat more, but a ten-fold improvement does not seem to be in the cards.• Chemists using GROPE-III can readily reproduce the true docking positions for drugs whose docking is known (but not to them) and can find very good docks for drugs whose true docks are unknown. The present tool promises to yield new chemistry research results; it is being actively used by research chemists.• The most valuable result from using GROPE-III for drug docking is probably the radically improved situation awareness that serious users report. Chemists say they have a new understanding of the details of the receptor site and its force fields, and of why a particular drug docks well or poorly.• We see various scientific/education applications for haptic displays but believe entertainment, not scientific visualization, will drive and pace the technology.• The hardware-software system technology we have used is barely adequate, and our experience sets priorities for future development.• Some unexpected perceptual phenomena were observed. All of these worked for us, not against us.
Extended free-form deformation: a sculpturing tool for 3D geometric modeling
Authors: Coquillart Sabine
Published: November 2005

Current research efforts focus on providing more efficient and effective design methods for 3D modeling systems. In this paper a new deformation technique is presented. Among other things, arbitrarily shaped bumps can be designed and surfaces can be bent along arbitrarily shaped curves.The purpose of this research is to define a highly interactive and intuitive modeling technique for designers and stylists. A natural way of thinking is to mimic traditional trades, such as sculpturing and moulding.Furthermore, with this deformation technique, the modeling tool paradigm is introduced. The object is deformed with a user-defined deformation tool.This method is an extension of the Free-Form Deformation (FFD) technique proposed by Sederberg and Parry [17].