bluuebunny/crossref_metadata_2025 huggingface dataset:
Comprehensible rendering of 3-D shapes
Authors: Saito Takafumi , Takahashi Tokiichiro
Published: November 2005

We propose a new rendering technique that produces 3-D images with enhanced visual comprehensibility. Shape features can be readily understood if certain geometric properties are enhanced. To achieve this, we develop drawing algorithms for discontinuities, edges, contour lines, and curved hatching. All of them are realized with 2-D image processing operations instead of line tracking processes, so that they can be efficiently combined with conventional surface rendering algorithms.Data about the geometric properties of the surfaces are preserved as Geometric Buffers (G-buffers). Each G-buffer contains one geometric property such as the depth or the normal vector of each pixel. By using G-buffers as intermediate results, artificial enhancement processes are separated from geometric processes (projection and hidden surface removal) and physical processes (shading and texture mapping), and performed as postprocesses. This permits a user to rapidly examine various combinations of enhancement techniques without excessive recomputation, and easily obtain the most comprehensible image.Our method can be widely applied for various purposes. Several of these, edge enhancement, line drawing illustrations, topographical maps, medical imaging, and surface analysis, are presented in this paper.
Reusable motion synthesis using state-space controllers
Authors: van de Panne Michiel , Fiume Eugene , Vranesic Zvonko
Published: November 2005

The use of physically-based techniques for computer animation can result in realistic object motion. The price paid for physically-based motion synthesis lies in increased computation and information requirements.
1
We introduce a new approach to realistic motion specification based on state-space controllers. A user specifies a motion by defining a goal in terms of a set of destination states. A state-space controller is then constructed, which provides an optimal-control solution that guides the object from an arbitrary starting configuration to a goal. Motions are optimized with respect to time and control energy. Becasue controllers are specified in terms of destination states only, it is easy to reuse the same controller to produce different motions (from different starting states), or to create a complex sequence of motions by concatenating several controllers. An implementation of state-space controllers is presented, in which realistic motions can be produced in real time. Several examples will be considered.
Building block shaders
Authors: Abram Gregory D. , Whitted Turner
Published: November 2005

This paper describes an implementation of Cook's "shade trees" in which shaders are described as networks of modules, building blocks, whose connections can be defined interactively.The high level interface to the shaders is a graphical editor which permits users to construct complex shaders by connecting shading elements in a network, in effect a graphical shading language. A low level interface to the shaders is also provided. In the low level interface, shading elements are programmed in a standard programming language and compiled into modules which can linked either at run time or compile time.Each link in the shading network represents a subroutine call. In essence, execution of the network is analogous to the execution of an interpreted language.
A language for shading and lighting calculations
Authors: Hanrahan Pat , Lawson Jim
Published: November 2005

A shading language provides a means to extend the shading and lighting formulae used by a rendering system. This paper discusses the design of a new shading language based on previous work of Cook and Perlin. This language has various types of shaders for light sources and surface reflectances, point and color data types, control flow constructs that support the casting of outgoing and the integration of incident light, a clearly specified interface to the rendering system using global state variables, and a host of useful built-in functions. The design issues and their impact on the implementation are also discussed.
The rendering architecture of the DN10000VS
Authors: Kirk David , Voorhies Douglas
Published: November 2005

The Appollo DN10000VS treats graphics as an integral part of the system architecture. Graphics requirements influence the entire system design. All floating-point computations for graphics are performed by the CPU(s), while rasterizing is handled by simplified hardware having no microcode. We decided to support alpha buffering, quadratic interpolation, and texture mapping directly in hardware. This partitioning reduces the cost of a high-end workstation, without sacrificing high rendering quality and performance. This paper describes some of the design trade-offs which led to the final system design.
High speed high quality antialiased vector generation
Authors: Barkans Anthony C.
Published: November 2005

A vector generation method is described in which a high quality image rendering scheme is coupled with a high speed scan-conversion algorithm.The rendering scheme consists of two parts. First a prefiltering method is used to antialias the vectors. Second a compositing technique is used to compose the vectors into the frame-buffer.The scan-conversion algorithm presented allows a single vector to be scan-converted by a either by a single processor or a set of processors running in parallel. When using parallel processors, antialiased vectors may be scan-converted and written to a frame store at the same high speed as aliased vectors. The VLSI technology used to implement this algorithm is capable of drawing over two million high quality antialiased vectors per second.
Ray tracing trimmed rational surface patches
Authors: Nishita Tomoyuki , Sederberg Thomas W. , Kakimoto Masanori
Published: November 2005

This paper presents a new algorithm for computing the points at which a ray intersects a rational Bézier surface patch, and also an algorithm for determining if an intersection point lies within a region trimmed by piecewise Bézier curves. Both algorithms are based on a recent innovation known as Bézier clipping, described herein. The intersection algorithm is faster than previous methods for which published performance data allow reliable comparison. It robustly finds all intersections without requiring special preprocessing.
A method of generating stone wall patterns
Authors: Miyata Kazunori
Published: November 2005

Recently, several kinds of mapping technology, such as texture mapping and bump mapping, have played a very important role in the realization of more realistic image synthesis. The textures to be mapped are often obtained by using an optical scanner or a video camera. However, it is not easy to obtain a suitable image by taking a photo. We consider it very important to be able to generate a variety of textures and patterns easily according to the requirements. This paper proposes a new method of generating stone wall patterns as a specific case of a generalized texture generator. The advantage of the method is that it allows the user to generate a variety of stone wall patterns by specifying a few simple parameters. We have applied it to a visual simulation system in order to represent such stone textures as walls, pavements, and steps. This paper also gives some examples of its applications.
MAPS
Authors: Fischer Michael
Published: November 2005

By approaching two and three-dimensional problems from the spatial viewpoint taken by the geographic sciences, the Multi-dimensional Analysis Processing System (MAPS) is able to achieve high efficiency and large capacity in many types of interactive graphics, simulation modeling, and image processing. Spatial relationships are presented by means of color images, rather than line drawings, facilitating interpretation and display of complex, continuous data sets. By integrating data base and CRT refresh storage into a single subsystem, MAPS is able to make extensive use of analog devices. This analog processing permits complex image transformations to be done at high speed and low cost. User interface is handled by the system-control minicomputer, and is designed to allow MAPS to serve as a powerful "perception amplifier", even for nontechnical users.
Graphics in APL
Authors: Bork Alfred M.
Published: November 2005

This document describes a graphic facility within APL. The terminals are assumed to be inexpensive timeshared graphic terminals equipped with an APL character set. We first describe functions in a graphic workspace and then APL primitives for graphing.Graphic APL is a shared processor at Irvine, called APLG. The current version is 6.1.
Basic graphics software
Authors: Meads Jon A.
Published: November 2005

Basic graphics software is system software for the application programmer designed to relieve him of the need for intimate knowledge of graphic devices. Ideally basic graphics software would be a common package for all users. However a more feasible approach would be to define distinct functions which should be common to the many packages which must be developed.
Graphics software for BASIC
Authors: Alpert Stephen R.
Published: November 2005

This article was prompted by the article written by Jon Meads in the Fall 1973 SIGGRAPH report. (1) A graphics package has been developed for use on Digital Equipment Corporation's GT40 and GT44 series of minicomputer-based graphics systems. Within the limitations of the machines, a package of graphics software was written to allow almost complete control of the display processor by a programmer using the language BASIC.
Building highway systems with computer graphic simulations
Authors: Moffett T. J.
Published: November 2005

A number of computer applications generate perspective drawings of proposed highway designs as a means of design evaluation. The use of this capability is rare in the United States. Examples, developed in France, show computer-generated perspective drawings simulating several actual highway design situations. Highway construction costs are rapidly increasing in the United States prompting a need for design optimization including wider use of computer-generated perspective and simulations. This is encouraging the development of network-supported intelligent interactive graphic terminals. Congressional testimony supports the need for better ways to communicate proposed highway and transportation system designs to citizen groups. Computer-generated dynamic simulations were used as a basis for Congressional testimony. Computer simulations have been proposed to evaluate alternate commercial signposting situations in the State of Oregon. Two techniques for producing color and landscape enhanced perspectives are available, and electronic microfilm recorders offer promise as a means of producing simulations. There is a growing need for computer-generated simulations for designing better highway systems, and the necessary experience and technology are available.
Computer graphics in urban and environmental systems
Authors: Phillips R. L.
Published: November 2005

The key role played by computer graphics in urban, regional, and environmental information systems is surveyed by reference to specific examples. While the interactive cathode-ray tube terminal is found to be the most valuable medium, other output devices such as printers and plotters are discussed as well. Elements of computer cartography and data base organization are introduced, followed by discussions of urban information and transportation network design systems, a regional analysis system, and air and water quality information systems. Specific recommendations are given for further research in data base design and display techniques, and for promising new hardware for use in geographically distributed data systems.
Three-dimensional data input by tablet
Authors: Sutherland I. E.
Published: November 2005

A large-area multiple-pen tablet system for three-dimensional data input is described. The large tablet area provides space for simultaneous use of several views of the three-dimensional object being digitized. The multiple pens enable the user to indicate a single point simultaneously in two such views, thus defining the three-dimensional position of the point.Five significant techniques are outlined. First, the large-area digitizing surface with multiple pens has proved to be an instrument very different from the more familiar single-pen small tablets. Second, a pair of two-dimensional positions is converted into a four-dimensional space and then back to three dimensions. Third, the specification of view areas, viewing directions, view positions, and coordinate axis is accomplished by giving examples directly in the viewing space rather than by specifying abstract viewing parameters. Fourth, an attitude about coordinate conversion using the inverse of a basis matrix is used throughout which automatically compensates for any tilt in the views on the tablet surface and any nonperpendicularity of the tablet axis. Fifth, the mathematics of converting from pairs of perspective views or pairs of photographs, while not new, is formulated simply in an appendix with several examples.
The art of natural graphic man-machine conversation
Authors: Foley J. D. , Wallace V. L.
Published: November 2005

The design of interactive graphic systems whose aim is good symbiosis between man and machine involves numerous factors. Many of those factors can be judged from the perspective of natural spoken conversation between two people.Guiding rules and principles for design of such systems are presented as a framework for a survey of design techniques for man-machine conversation. Attention is especially focused on ideas of action syntax structuring, logical equivalences among action devices, and avoidance of psychological blocks to communication.
Raster graphics for spatial applications
Authors: Fischer Michael A. , Nunley Robert E.
Published: November 2005

The greatest effective bandwidth of the eye is for changes in color and texture, so why does computer graphics emphasize line-drawings? Questions such as this brought about the MAPS Project in 1971 for the purpose of developing graphics systems suitable for geographic applications. The MAPS-1 system, operational since September 1974, and the MINIMAPS system now under development achieve high performance at low cost for real-time interactive image processing, dynamic spatial simulation modeling, and spatial data base management. Standard color television is the primary output medium, facilitating communication of dynamic results. MINIMAPS employs a memory-centered architecture in which processing is distributed by function among a series of microprocessors. The picture processor encodes data matrices directly into color images. The system is highly interactive, performing most functions in 1/30 second. Its control language, packaging and environment are designed to encourage users to play with images, using the system as a perception amplifier.
Digital plotting from a line generator format
Authors: Capowski Joseph J.
Published: November 2005

A hard copy capability was needed for the CRT of a PDP-11/LDS-2 graphics facility. Available hardware was inconvenient or unsatisfactory for several reasons. An Hewlett-Packard 7210 A Digital Plotter was selected and an interface from standard line generator format to the plotter was designed and built. The results are a fast, quiet, high-quality hard copy capability requiring negligible software.
A high-speed interface to Tektronix 401x series terminals
Authors: Hamlin Griffith A.
Published: November 2005

A high-speed interface to the Tektronix 401x series of storage tube terminals has been developed that allows communication with the terminal at rates up to 300 kbit/s. The interface occupies one slot within the terminal and can be reproduced in a short time for about $200-worth of readily available parts. Hardware First-In-First-Out (FIFO) buffers solve problems with data overrun at high speeds, and allow us to realize sustained rates very near the maximum 300-kbit/s rate for our dominant type of image, which is characterized by very many short vectors. The interface will accept standard RS232 asynchronous serial data at any baud rate up to 300 kbit/s, or byte-parallel data with a slight modification.
Hidden surface elimination for complex graphical scenes
Authors: Boinodiris S.
Published: November 2005

An extension to the Algorithm of Recursive Descent, introduced by Clark is presented for improving high speed techniques in hidden surface elimination. Whenever the average number of opaque primitives per occupied raster element becomes large, the algorithm presented tends to eliminate unnecessary depth evaluations. In complex graphical scenes which are executed by parallel processing structures interactively, the presented algorithm may provide considerable processing savings in related computer graphics processes.
Design considerations for Picture Production in a Natural Language graphics system
Authors: Brown D. C. , Chandrasekaran B.
Published: November 2005

This ongoing research is concerned with the construction of a Picture Production system which has embedded knowledge. The paper discusses the motivation for such a system and gives reasons why knowledge should be included about the objects to be displayed. Some questions and commands in Natural Language are shown to give clues as to the natural structure of such a system. An outline of a design for a Picture Production system is presented via the use of a simple example.
Graphical data structures
Authors: Hardwick Martin
Published: November 2005

A graphical data structure is essentially a mathematical model of the data in a picture. This model describes the properties of that data and therefore it describes relationships which exist in that data. In this paper a method is described for constructing graphical data structures so that the relationships expressed in those structures correspond to relationships which exist in the "real" world. These relationships can then be exploited so that any data which has that structure can be manipulated in a "real" world manner. This method is based on an extended schema for relational databases which is manipulated using an extended APL notation.
Calculation of B-spline surfaces using digital filters
Authors: Schaffner Stuart C.
Published: November 2005

A (potentially large) MxN grid of B-spline control points is an attractive database for the representation of a curved surface. The properties of B-splines allow precise control over surface smoothness and ensure that local changes to the surface will require only local changes to the database. One difficulty in applying this technique is that the grid of control points does not in general lie on the surface it generates. Given an MxN grid of points, one would like to be able to generate a B-spline surface which passes through all points in the given grid.A straightforward but time-consuming solution to this problem would require the inversion of one MxM and one NxN matrix. Instead, we solve the problem with digital filters. The grid of surface points is passed through a set of first-order recursive digital filters to produce the grid of control points. This method requires time linear in the number of grid points, works without modification for all values of M and N, and has excellent stability.
Computer rendering of fractal curves and surfaces
Authors: Carpenter Loren C.
Published: November 2005

Fractals are a class of highly irregular shapes that have myriad counterparts in the real world, such as islands, river networks, turbulence, and snowflakes. Classic fractals include Brownian paths, Cantor sets, and plane-filling curves. Nearly all fractal sets are of fractional dimension and all are nowhere differentiable.Previously published procedures for calculating fractal curves employ shear displacement processes, modified Markov processes, and inverse Fourier transforms. They are either very expensive or very complex and do not easily generalize to surfaces. This paper presents a family of simple methods for generating and displaying a wide class of fractal curves and surfaces. In so doing, it introduces the concept of statistical subdivision in which a geometric entity is split into smaller entities while preserving certain statistical properties.
The AGF plotfile
Authors: Enderle G. , Giese I. , Krause M. , Meinzer H. P.
Published: November 2005

The AGF plotfile is a sequential file for storage and transportation of graphics information. It contains records describing graphics primitives (points, vectors, polylines, texts) and their attributes. The primitives may be two- or three-dimensional. Raster graphics records are included in the plotfile. The structure of the plotfile is described, the capabilities of an interpreter are outlined, and it is shown how the plotfile can be interfaced to the proposed SIGGRAPH-CORE graphics system.
A hierarchical model of a graphics system
Authors: Kilgour A. C.
Published: November 2005

This paper presents a model of a graphics system as a hierarchy of communicating modules. Each module has two input ports and two output ports, and may be regarded as a generalisation of the "software filter" proposed by Kernighan & Plauger [KERN76]. Each module accepts commands from a high r-level module (or the application program) and event records from a lower-level module. A general framework for the internal organisation of a module is presented, which allows for internal feedback from the event record input port to the low-level output port, the specification and control of concurrent background processes (e.g. for continuous picture modification), and the dynamic modification of the feedback behaviour. Extending the terminology introduced by Houlton & Corman [MOULT76], a module is seen as a "programmable graphics multi-processor".Because feedback behaviour is under the control of the superior module, the proposed model is more flexible and general than that underlying currently proposed standards, e.g. the ACM GSPC "Core" System [GSPC77]. The application of the model to the design of a satellite system controlling a random-scan refreshed display, and a module to control a simple raster-scan terminal, are described, and the implications for current work on graphics standards discussed.
A transformation structure for animated 3-D computer graphics
Authors: Keith Stephan R.
Published: November 2005

This paper discusses a means of describing in a generalized manner a transformation structure that will accommodate varying orders and levels of transformations on sets and subsets of points describing objects. These structures were designed specifically for animation of multiple set objects.A solar system, a multiple gimbaled gyro and a butterfly consist of such sets of points and subsets of points, each requiring different orders of translations and rotations.For this initial version, a binary tree structure is used to describe either a rotation, a translation or object description at each node. A more general n-ary tree structure could have been used, but resources are limited and the quickest implementation was generated to test the ideas for this paper.For generality and ease of description, 4 x 4 matrices are used. Each matrix type is discussed and fully displayed to minimize confusion between conventional arrays and those used in this paper. Transformation methods and parsing methods are discussed.The scope of this paper is to discuss a technique and not its implementation; thus printouts are omitted. Also, this paper is intended as an informal means of communicating one of many methods which will do the same thing.
Boundary detection in 3-dimensions with a medical application
Authors: Artzy Ehud , Herman Gabor T.
Published: November 2005

A graph theoretical approach is taken to solve the problem of detecting the surface of a connected subset of three-dimensional space. Motivation and application are provided by the need to display the three-dimensional appearance of internal organs of a human body based on x-rays from multiple directions. The method is implemented on a minicomputer and is illustrated by the display of the ventricular system of the human brain. In that example, the boundary detection involves selecting 10,000 surface elements out of a pool of over 1.5 million. In spite of the enormous size of the problem, the detection takes less than 30 seconds on a minicomputer.
Perspective mapping of planar textures
Authors: Perny D. , Gangnet M. , Coueignoux Ph.
Published: November 2005

Perspective mapping of planar textures is discussed along two directions.First we study the perspective mapping of a plane onto another plane. We show that the point to point computation involved can be broken down to a simple 2-D homology compounded with two 2-D rotations. Such a result is very useful to speed up texture mapping.Second we study how to render texture mapping most accurate according to digital signal theory. We define a new methodology for filtering using the inverse of the linear transformation tangent to the perspective at each pixel.Extensions can be made to a large class of patches and of surface transforms.
Device independent and decentralized graphic systems
Authors: Guttmann Herbert , Weiss Johann
Published: November 2005

Increasing costs in software development and maintenance call for portability of user programs. Difficulties arise from the great diversity of input and display devices. Investigations of basic principles of computer graphics lead to the proposal of standards in Europe and USA in order to achieve device independence, a presupposition for program portability. Implementations of these standards should take advantage of pseudocode and decentralization. Providing peripheral devices with local memory and local processing power improves system performance. By use of pseudocode the definition of device independent interfaces between the host computer and peripheral units becomes feasible.
Logical pick device simulation algorithms for the core system
Authors: Garrett Michael T.
Published: November 2005

The specifications for logical pick devices in the Status Report of the Graphics Standards Planning Committee are reviewed followed by a short, general discussion of Pick simulation. Then, the simulation of Picks by point selection and segment display file processing is discussed in detail with emphasis on the improvement of performence using extents. Finally, the picking algorithms of two major Core implementations are outlined.
Current literature in computer graphics and interactive techniques
Authors: Schrack G. F.
Published: November 2005

The purpose of the References and Reviews Department is to collect and to disseminate rapidly as many publication citations of interest as come to the attention of the editor. Areas of interest cover all aspects of Computer Graphics and Interactive Techniques, particularly the following: man-machine interaction, graphical representation of data, data structures, data base searching and retrieval, computer aided design, graphic control systems, network design, computer art, computer animation, graphic software, graphic hardware, and the areas listed in the taxonomy by the GSPC Subcommittee (see Computer Graphics, 12(December 1978), 40--45).Technical reports, Master's and Ph.D. theses will be included in the list of current literature, provided that copies of these will be generally available, either on request, through interlibrary loan, on microfilm, microfiche or other means. Such references should be submitted to the departmental editor (address see front inside cover).
The perception of coherent motion in two-dimensional patterns (abstract only)
Authors: Adelson Edward H. , Movshon J. Anthony
Published: November 2005

When one looks at a two-dimensional scene of moving objects, one can usually assign a velocity to each point in that scene with little effort. This suggests that some early visual processes are able to generate a two-dimensional velocity map using fast parallel computations. But it is not obvious how this should be done, and we are currently trying to understand how the human visual system does it.
Determining the instantaneous axis of translation from optic flow generated by arbitrary sensor motion (abstract only)
Authors: Rieger J. H. , Lawton D. T.
Published: November 2005

This paper develops a simple and robust procedure for determining the instantaneous axis of translation from image sequences induced by unconstrained sensor motion. The procedure is based upon the fact that difference vectors at discontinuities in optic flow fields generated by sensor motion relative to a stationary environment are oriented along translational field lines. This is developed into a procedure consisting of three steps: 1) locally computing difference vectors from an optic flow field; 2) thresholding the difference vectors; and 3) minimizing the angles between the difference vector field and a set of radial field lines which correspond to a particular translational axis. This method does not require a
priori
knowledge about sensor motion or distances in the environment. The necessary environmental constraints are rigidity and sufficient variation in depth along visual directions to endow the flow field with discontinuities. The method has been successfully applied to noisy, sparse, and low resolution flow fields generated from real world image sequences. Experiments are reviewed which indicate that the human visual system also utilizes discontinuities in optic flows in determining self-motion. In addition, due to the computational simplicity of the procedure, hardware realization for real-time implementation is possible.
Adapting optical-flow to measure object motion in reflectance and x-ray image sequences (abstract only)
Authors: Cornelius Nancy , Kanade Takeo
Published: November 2005

This paper adapts Horn and Schunck's work on optical flow to the problem of determining arbitrary motions of objects from 2-dimensional image sequences. The method allows for gradual changes in the way an object appears in the image sequence, and allows for flow discontinuities at object boundaries. We find velocity fields that give estimates of the velocities of objects in the image plane. These velocities are computed from a series of images using information about the spatial and temporal brightness gradients. A constraint on the smoothness of motion within an object's boundaries is used. The method can be applied to interpretation of both reflectance and x-ray images. Results arc shown for models of ellipsoids undergoing expansion, as well as for an x-ray image sequence of a beating heart.
Tracking three dimensional moving light displays (abstract only)
Authors: Jenkin Michael
Published: November 2005

A method is presented for tracking the three-dimensional motion of points from their changing two-dimensional perspective images as viewed by a nonconvergent binocular vision system. The algorithm relies on a general smoothness assumption to guide the tracking process, and application of the tracking algorithm to a three-dimensional moving light display based on Cutting's Walker program as well as other domains are discussed.Evidence is presented relating the tracking algorithm to certain beliefs about neurophysiological structures in the visual cortex.
Determining motion parameters for scenes with translation and rotation (abstract only)
Authors: Jerian Charles , Jain Ramesh
Published: November 2005

A study of methods that determine the rotation parameters of a camera moving through synthetic and real scenes is conducted. Algorithms that combine ideas of Jain and Prazdny are developed to find translational and rotational parameters. An argument is made for using hypothesized motion parameters rather than relaxation labelling to find correspondence.
A hybrid approach to structure-from-motion (abstract only)
Authors: Bobick Aaron
Published: November 2005

A method is presented for computing structure from the motion of rigid objects which are rotating about a fixed axis. The input consists of two discrete frames containing the positions and instantaneous direction vectors of three points in orthographic projection. Because only the direction of the velocity vectors and not their magnitudes is needed, the method is insensitive to errors in velocity magnitude estimation. This type of computation could be important in recovering the 3-dimensional structure of objects under dynamic viewing conditions because viewer motion about stationary objects will generate fixed axis rotations.
Perception of rotation in depth
Authors: Braunstein Myron L.
Published: November 2005

There are a variety of ways in which motion in the environment can provide information about three-dimensional relationships. One transformation that has received increasing attention in both the visual perception literature and in the machine vision literature is rotation in depth. This transformation, which includes any rigid rotation other than a rotation about the line of sight, can provide both a strong impression of depth and specific information about three-dimensional relationships in a rotating object or pattern. Computational theories have been developed concerning the relationships that an observer can potentially extract from the information available in this transformation. If computational theories are to be compared to human performance, a systematic body of data on human perception of rotation in depth is required. Such a body of data has been developing, especially in the last few years. Most of these studies have used computer animation techniques introduced into this area of research by Green. It is now possible to derive some preliminary conclusions from these data about what information is actually used by observers, what sources of information are dominant when multiple sources are available, and what errors occur in perception that can provide insights into the processes that observers apply to this information.The objective of this paper is to bring together these empirical findings concerning the ability of human observers to perceive three-dimensional relationships on the basis of rotation in depth. It is intended to systematize and clarify the current state of knowledge in this area. The following sections are organized about a series of conclusions, ranging from general to specific, concerning three major issues in the perception of objects undergoing rotation in depth. The first is the relationship between perceived depth and perceived relative distance in a rotating object. Perceived depth refers to the three-dimensional structure of an object, without regard to the position of the observer (e.g., the perception of a sphere as a sphere rather than as a circle). Perceived relative distance (or depth order) refers to the perception of which parts of an object are closer and which are more distant (e.g., which is the near hemisphere in a transparent sphere). Perceived relative distance in rotating objects is usually measured with direction of rotation judgments. The remaining two issues concern the variables which determine perceived depth and those which determine judgments of relative distance.
Perceiving and recovering structure from events (abstract only)
Authors: Cutting James E.
Published: November 2005

How do perceivers identify a moving object as seen against a changing background? How do figure and ground separate? Such questions have engaged psychologists for at least seventy years. In particular, the Gestalt psychologists were deeply concerned with the latter, but had only the illdefined notion of
common fate
, or uniform density, for dealing with the former. The coherent flow of a moving object is seen, somehow, by extracting those aspects of the whole that segregate it from the ground; the uniform destiny of all parts of the object was thought both to make the whole cohere and to separate the whole from all else. Two pairs of ideas, from two researchers who came out of the Gestalt tradition, helped elucidate the notion of common fate as applied to motion perception.
Motion analysis of grammatical processes in a visual-gestural language (abstract only)
Authors: Poizner Howard , Klima Edward S. , Bellugi Ursula , Livingston Robert B.
Published: November 2005

Movement of the hands and arms through space is an essential element both in the lexical structure of American Sign Language (ASL), and, most strikingly, in the grammatical structure of ASL: it is in patterned changes of the movement of signs that many grammatical attributes are represented. These grammatical attributes occur as an isolable superimposed layer of structure, as demonstrated by the accurate identification by deaf signers of these attributes presented only as dynamic point-light displays. Three-dimensional computer graphic analyses were applied in two domains, to quantify the nature of the 'phonological' (formational) distinctions underlying the structure of grammatical processes in ASL. In the first, we show that for one 'phonological' opposition,
evenness/unevenness
of movement, a ratio of maximum velocities throughout the movement perfectly captures the
linguistic
classification of forms along this dimension. In the second, we map out a two-dimensional visual-articulatory space that captures in terms of signal properties, relevant relationships among movement forms that were independently posited as linguistically relevant. The fact that we are finding direct correspondences between properties of the signal and properties of the 'phonological' system in sign language, may arise in part because in sign languages, unlike in spoken languages, the movements of the articulators themselves are directly observable, and, also in part, because of the predominantly layered 'phonological' organization of sign language.
"Graphical marionette" (abstract only)
Authors: Ginsberg Carol M. , Maxwell Delle
Published: November 2005

Many person-modelling 3-D animation systems are currently being developed, but often suffer from confusing and elaborate user interfaces. Given over 200 degrees of freedom, the human form is capable of such intricate motion that its specification and display presents considerable difficulty to both animators and animation systems designers. Given such difficulties with single figures, the orchestration of several in parallel remains a major challenge. In pursuit of understanding thoroughly this complex motion of human beings, while faced with the difficulty of modelling the human form using conventional computer graphics techniques, the actual physical mien of the graphic figure is sometimes relegated a secondary status. A primitive and unconvincing appearance is the usual result. Our research in this field addresses these issues of user interface, motion, and expressive appearance within an animation application.
A multiple track animator system for motion synchronization (abstract only)
Authors: Fortin D. , Lamy J. F. , Thalmann D.
Published: November 2005

MUTAN (MUltiple Track ANimator) is an interactive system for independently animating three-dimensional graphical objects. MUTAN can synchronize different motions; it is also a good tool for synchronizing motion with sound, music, light or smell. To indicate moments in time, marks are associated with appropriate frame numbers. MUTAN enables the marks to be manipulated. An animator can also adjust one motion without modifying the others. To make this possible, MUTAN handles several tracks at a time (as in sound reproduction). All animation constraints for a graphical object are recorded on each track. Some simple but powerful commands allow the animator to manipulate marks, tracks and frames. MUTAN is part of a complete 3D shaded animation system including the CINEMIRA computer animation language based on actor and camera data types, the 3D HORIZON graphics editor and a 3D digitizing program.
Knowledge-based animation (abstract only)
Authors: Zeltzer David
Published: November 2005

In constructing a goal-directed system for automatic motion synthesis for computer animation, the essential problem is to account for the extraordinary flexibility and adaptability exhibited by moving creatures. The selective
potentiation
and
depotentiation
of elements of a hierarchy of motor control programs is a key to the generation of adaptive motor control. The constraints on motion sequences are analyzed, and mechanisms for achieving continuity of movements are discussed. The organization of two data bases containing knowledge about the simulated environment and about available movements is described. An example showing the interaction between the motion control system and the data bases is presented.
3D balance in legged locomotion
Authors: Murthy Seshashayee S. , Raibert Marc H.
Published: November 2005

This paper explores the notion that the motion of dynamically stable 3D legged systems can be decomposed into a planar part that accounts for large leg and body motions that provide locomotion, and an extra-planar part that accounts for subtle corrective motions that maintain planarity. The large planar motions raise and lower the legs to achieve stepping, and they propel the system forward. The extra-planar motions ensure that the legged system remains in the plane. A solution of this form is simple because 3D dynamics do not play an important role.We develop a model of a 3D one legged hopping machine that incorporates a springy leg of non-zero mass and a two axis hip. The hopping machine is modeled as an open loop linkage that has different configurations in flight and in stance. Behavior at transitions between phases is calculated by invoking conservation of momentum. We have decomposed control of the model into four parts that control hopping height, forward velocity, body attitude, and spin. Hopping height is controlled by regulating vertical energy. Velocity is controlled by placing the foot fore and aft during flight. Body attitude is controlled by torquing the hip during stance. Spin is controlled by placing of the foot outside the plane of motion. Simulation data are presented which show that these control algorithms result in good control of velocity, body attitude and spin, while traveling along a straight desired path.
Graphical input interaction technique (GIIT)
Authors: Thomas James J. , Hamlin Griffith
Published: November 2005

The contents of this document are the result of intensive discussions among the workshop participants. The names listed by each section are the discussion leaders and principal editors. Without the dedicated enthusiam from all the participants, the ideas presented could not have been formulated.
Managing graphical resources
Authors: Rosenthal David S. H.
Published: November 2005

The development of interactive graphics software has separated into two apparently incompatible streams. The mainstream, exemplified by GKS and the Core, and a "RasterOp" stream, exemplified by Smalltalk and the Carnegie-Mellon CANVAS package. In the mainstream, the important concepts are viewing, segments, output primitives, and virtual input devices. In the RasterOp stream, the important concepts are windows, the refresh hierarchy, and pointing for input.Although it is easy in the mainstream to provide libraries of output-only routines for general use, it is difficult to do the same for input. Although it is possible to write device-independent interactive applications using mainstream techniques, the quality of the user interface may vary wildly as they are ported. These problems are caused by the mainstream's lack of the mechanisms needed to control the allocation of real graphical resources within the application:1. No hierarchy of pictures on the view surface. All parts of the application have control over all parts of the view surface.2. No connection between viewing and segmentation. The viewing parameters used to create a segment are not attributes of the segment.3. All parts of the application have access to all the input devices. It is up to each part to decide if an input is relevant, or if not, what to do with it.
A catalogue of graphical interaction techniques
Authors: Green Mark
Published: November 2005

The design of good user interfaces is more of an art form than a science or engineering discipline. One of the problems faced by user interface designers is choosing the appropriate interaction technique for particular applications. At the present time the designer must rely on his memory and experience in making this choice. Our solution to this problem is the production of an interaction technique catalogue containing the descriptions of a large number of standard interaction techniques. We present the basic principles and organization of this catalogue along with some samples of its contents. The complete catalogue can be found in Green [5].
Blueprint for an anatomical/surgical computer
Authors: Canter John David
Published: November 2005

An anatomical/surgical computer system has been hypothesized, and many of its attributes have been successfully simulated on an Adage AGT/10 Graphics computer. The anatomical/surgical computer provides graphical data processing capabilities for medical students, researchers and practitioners in the analysis of human anatomy, the evaluation of surgical techniques, and the investigation of diseases, their formation and development. The system incorporates a computer-driven full color, three-dimensional cathode ray tube display on which is depicted a simulated human organism. Anatomical studies, surgical procedures, and clinical investigations may be symbolically performed under user control, with the system exhibiting two-way communications between itself and the human operator.
KARMA
Authors: Gracer F. , Blasgen M. W.
Published: November 2005

The creation of an animated film begins with a story-board consisting of a series of frames. Between each pair of storyboard frames, the artist must draw many intermediate frames to produce smooth animation. This paper describes an interactive computer graphics program which automatically produces the intermediate frames for review or filming. The program runs on an IBM 1130/2250 with a Sylvania tablet attached to the 1130. The user can draw the storyboard frames on the tablet and ask for animation on the 2250. The intermediate frames are calculated using linear interpolation.
Volume probes: interactive data exploration on arbitrary grids
Authors: Speray Don , Kennon Steve
Published: November 2005

A taxonomy of computational grids used in scientific and engineering practice is presented and a technique for cutting them by, and displaying data on, 2D surfaces is developed. When sliced by a surface, these grids give rise to a graph G(C, F) where C, the nodes, are the intersected cells and F, the arcs, are their connectivity across faces. Starting from any cell known to be intersected by the surface (a seed), G is traversed breadth-first and is constructed locally on the fly, that is, only the spreading "front" explicitly exists at any time. Only sliced cells are visited, shared computed values such as edge intersections are passed to neighbors, and most of the geometric work is done via table lookup. A seed cell is found by fence-hopping from any cell to a distinguished point on the surface.This means of slicing grids is then utilized in an effective visualization tool. Concentrating on planar surfaces, local coordinate systems are defined for constructing clipping windows and linear transformations within the planes which further reduces display time and allows effects such as zooming within the windows. Several of these planar windows are then organized into various objects, called probes, that can exploit the mind's "retinal memory" when repeatedly swept through amorphous data.