waashk/acm huggingface dataset:
what is visual interactive simulation? (and is there a methodology for doing it right?)  visual interactive simulation (vis) is the development and application of simulations which produce a dynamic display of the system model, and allow the user to interact with the running simulation. this paper presents the basic ideas behinds vis, and the methods whereby it can be achieved. the benefits of using vis, and folklore about the advantages and problems of vis, are presented. it is concluded that amongst those practicing vis a number of competing decision aiding methodologies exist, and that a single unifying methodology is necessary for the advancement of vis.  robert m. o'keefe
infant: a modular approach to natural language processing  the infant system is a working natural language processing system that approaches language analysis through the integration of a large number of interdependent procedural modules. by themselves the modules perform specific, predictable, and rather mundane tasks; taken together, they make up an understanding system whose 'beliefs' and responses are varied and unpredictable. thus a type of emergent behavior is demonstrated by the system. this paper describes the overall modular design of infant, and illustrates through sample conversations some of its capabilities and deficiencies.  paul buchheit
learning to recommend from positive evidence  in recent years, many systems and approaches for recommending information, products or other objects have been developed. in these systems, often machine learning methods that need training input to acquire a user interest profile are used. such methods typically need positive and negative evidence of the user's interests. to obtain both kinds of evidence, many systems make users rate relevant objects explicitly. others merely observe the user's behavior, which fairly obviously yields positive evidence; in order to be able to apply the standard learning methods, these systems mostly use heuristics that attempt to find also negative evidence in observed behavior.  in this paper, we present several approaches to learning interest profiles from positive evidence only, as it is contained in observed user behavior. thus, both the problem of interrupting the user for ratings and the problem of somewhat artificially determining negative evidence are avoided.  the learning approaches were developed and tested in the context of the web- based elfi information system. it is in real use by more than 1000 people. we give a brief sketch of elfi and describe the experiments we made based on elfi usage logs to evaluate the different proposed methods.  ingo schwab wolfgang pohl ivan koychev
what is text, really? the way in which text is represented on a computer affects the kinds of uses to which it can be put by its creator and by subsequent users. the electronic document model currently in use is impoverished and restrictive. the authors argue that text is best represented as an ordered hierarchy of content object (ohco), because that is what text really is. this model conforms with emerging standards such as sgml and contains within it advantages for the writer, publisher, and researcher. the authors then describe how the hierarchical model can allow future use and reuse of the document as a database, hypertext, or network. steven j. derose david g. durand elli mylonas allen h. renear
a structure from manipulation for text-graphic objects  the general purpose graphics systems of the future will need a simple logic for visual objects---one structure underlying both text and graphics. as an experiment, perhaps the immediate handling of visual objects by the user can provide the starting point for developing that structure. this paper describes the pam graphics system, in which the structure of text-graphic objects arises directly out of manual manipulation. the needs of manual manipulation determine the text-graphic pattern as the simplest organizing structure for images; pam stands for pattern manipulating. the pam system is designed for the agile manipulation of text-graphic patterns---first manually, and then, later, programmatically.  starting from this strict 'front-in' viewpoint---where immediate manipulation (hand powered animation) was to be the primary application---a 'manipulative grammar' was evolved to give the user a simple yet powerful handle on text- graphic images. this grammar turned out to be a generalization of lisp syntax from textual symbolic expressions to text-graphic forms, structuring such forms as trees and then offering:  @@@@spatial grabbing of objects into attention  @@@@tree guided attention shifters like first, rest, next, and up  spatial & tree manipulations on any object in attention.  @@@@the resulting structures also offer surprising computational power (in a manner directly analogous to the way the basic list structures and functions of lisp give rise to the flexibility and power of a full blown lisp system, mccarthy and talcott [1]), leading finally to computing with text-graphic forms. consequently, a semantic function is added to supplement the basic manipulative grammar:  @@@@evaluation of object in attention, result displayed at the cursor. evaluation supports facilities like naming (and thus saving) visual objects, programming, and creation of menus (patterns of evaluatable function objects).  an experimental version of the pam system has been implemented in maclisp at the stanford artificial intelligence lab.  fred h. lakin
reflection vector shading hardware  surface reflections of an environment can be rendered in real time if hardware calculates an unnormalized reflection vector at each pixel. conventional perspective-correct texture hardware can then be leveraged to draw high- quality reflections of an environment or specular highlights in real time. this fully accommodates area light sources, allows a local viewer to move interactively, and is especially well suited to the inspection of surface orientation and curvature. by emphasizing the richness of the incoming illumination rather than physical surface properties, it represents a new direction for real-time shading hardware.  douglas voorhies jim foran
distributed ray tracing  ray tracing is one of the most elegant techniques in computer graphics. many phenomena that are difficult or impossible with other techniques are simple with ray tracing, including shadows, reflections, and refracted light. ray directions, however, have been determined precisely, and this has limited the capabilities of ray tracing. by distributing the directions of the rays according to the analytic function they sample, ray tracing can incorporate fuzzy phenomena. this provides correct and easy solutions to some previously unsolved or partially solved problems, including motion blur, depth of field, penumbras, translucency, and fuzzy reflections. motion blur and depth of field calculations can be integrated with the visible surface calculations, avoiding the problems found in previous methods.  robert l. cook thomas porter loren carpenter
fbram: a new form of memory optimized for 3d graphics  fbram, a new form of dynamic random access memory that greatly accelerates the rendering of z-buffered primitives, is presented. two key concepts make this acceleration possible. the first is to convert the read-modify-write z-buffer compare and rgbα blend into a single write only operation. the second is to support two levels of rectangularly shaped pixel caches internal to the memory chip. the result is a 10 megabit part that, for 3d graphics, performs read- modify-write cycles ten times faster than conventional 60 ns vrams. a four-way interleaved 100mhz fbram frame buffer can z-buffer up to 400 million pixels per second. working fbram prototypes have been fabricated.  michael f. deering stephen a. schlapp michael g. lavelle
an expert system for evaluation of sports injuries (abstract only)  a knowledge-base system was developed using the insight 2+ rule-based expert system tool. the user is questioned about the area of the injury, such as the foot, ankle, knee, or elbow. the inference engine then selects the appropriate knowledge base. symptoms of the injury are requested from the user, who is also instructed to perform manual tests on the injured part. the input is evaluated through a set of rules, and the exact type of injury is evaluated as well as the severity. a recommended treatment is then suggested.  the user is expected to have a basic knowledge of athletic training terms and sports medicine anatomy; however, screen displays can be requested on certain technical details by the user. this system can be used as a training tool for student athletic trainers and can also be used as a substitute in the absence of a more experienced trainer. our experiences with the design of this system, our work with experts, and the implementation will be discussed along with a report about the performance and use of the system.  j. m. gardner j. h. morrel k. e. lagle
modeling viewpoints for assessing reliability  this paper is the third in a series of papers dealing with model evolution and its importance in problem-solving when employing simulation as an analysis tool. in the paper, reliability assessment is used as a vehicle for presenting modeling viewpoints and constructs. as in the previous papers, the assessment of the worth of a model is not made. the paper describes modeling viewpoints and procedures in a reliability assessment context and describes the need for being able to build more detailed models from simpler models. the basic hypothesis of the paper is that model evolution is a way of life for the simulationist.  a. alan b. pritsker
a conceptual model of raster graphics systems  in this paper we present a conceptual model of raster graphics systems which integrates, at a suitable level of abstraction, the major features found in both contemporary and anticipated graphics systems. these features are the refresh buffer; the image creation (scan-conversion) system; the single address-space architecture which integrates the address space of the refresh buffer with those of the image creation system and the associated general- purpose computer; the rasterop or bitblt instructions found in some single address-space architectures; the video look-up table, and refresh buffer to screen transformations. also included are the major components from the conceptual model of vector graphics systems which are embodied in the acm/sigggraph/gspc core system. using the conceptual model as a base, we proceed to sketch out the capabilities we have defined in a substantial addition to the core system. the capabilities are currently being implemented as part of the george washington university core system.  james acquah james foley john sibert patricia wenner
graphics standards status report (panel session)  two status reports will be presented. the first report describes the activities of working group 2 (computer graphics) of the international standards organization subcommittee on programming languages (iso tc97/sc5/wg2). actions taken in recent wg2 meetings in october, 1979, and june, 1980, will be covered. significant proposals being examined by wg2 include gks, a german-designed 2d graphics package derived from the siggraph gspc core system proposals, and videotex, a canadian-designed protocol text communication that includes geometrically coded picture images.  the second status report describes the recent activities of the american national standards institute (ansi) technical committee x3h3, computer graphics. this includes the committee status, international activities, key technical issues, and future plans.  peter bono p. tenhagen janet chin p. bono j. encarnacao j. michener
pomegranate: a fully scalable graphics architecture  pomegranate is a parallel hardware architecture for polygon rendering that provides scalable input bandwidth, triangle rate, pixel rate, texture memory and display bandwidth while maintaining an immediate-mode interface. the basic unit of scalability is a single graphics pipeline, and up to 64 such units may be combined. pomegranate's scalability is achieved with a novel "sort- everywhere" architecture that distributes work in a balanced fashion at every stage of the pipeline, keeping the amount of work performed by each pipeline uniform as the system scales. because of the balanced distribution, a scalable network based on high-speed point-to-point links can be used for communicating between the pipelines.  pomegranate uses the network to load balance triangle and fragment work independently, to provide a shared texture memory and to provide a scalable display system. the architecture provides one interface per pipeline for issuing ordered, immediate-mode rendering commands and supports a parallel api that allows multiprocessor applications to exactly order drawing commands from each interface. a detailed hardware simulation demonstrates performance on next- generation workloads. pomegranate operates at 87-99% parallel efficiency with 64 pipelines, for a simulated performance of up to 1.10 billion triangles per second and 21.8 billion pixels per second.  matthew eldridge homan igehy pat hanrahan
perception-guided global illumination solution for animation rendering  we present a method for efficient global illumination computation in dynamic environments by taking advantage of temporal coherence of lighting distribution. the method is embedded in the framework of stochastic photon tracing and density estimation techniques. a locally operating energy-based error metric is used to prevent photon processing in the temporal domain for the scene regions in which lighting distribution changes rapidly. a perception-based error metric suitable for animation is used to keep noise inherent in stochastic methods below the sensitivity level of the human observer. as a result a perceptually-consistent quality across all animation frames is obtained. furthermore, the computation cost is reduced compared to the traditional approaches operating solely in the spatial domain.  karol myszkowski takehiro tawara hiroyuki akamine hans-peter seidel
abstracts of japanese computer algebra meeting in kyoto these are abstracts of talks given at the 14th rims (research institute for mathematical sciences) meeting of computer algebra and its applications in mathematical researches. the meeting took place from 20 to 22 in november 1995. in the meeting, 31 talks were presented. here, short abstracts of almost all talks are shown. if readers have an interest in in some of abstracts, please contact with authors directly or send a message to matu-tarow noda at the address above. proceedings of the meeting were already published from rims as rims memoir 941, entitled _theory of computer algebra and its applications._ matu-tarow noda
artists augmented by agents (invited speech)  computers can be very helpful to us by performing tasks on our behalf. for example, they are very good at performing calculations, storing information and producing visualisations of objects that do not yet exist as a made artifact. increasingly, however, a different role is being found for the computer. it is the role of a catalyst, or a stimulant, to our own creative thinking. in such cases the computer is not primarily performing a task for us and generating an answer within itself, rather it is helping us to generate answers within ourselves. the computer helps us think creatively. this role for the computer can be illustrated in the context of computer support to creative design. in order to design computer systems that support the creative process, it is important to understand that process well enough to predict what might help, rather than hinder. given such research, we may begin to define the characteristics of what the computer must do in order to augment creative thinking. the paper explores a particular application of intelligent user interfaces:- the augmentation of creative thought in artists.  ernest edmonds
beam tracing polygonal objects  ray tracing has produced some of the most realistic computer generated pictures to date. they contain surface texturing, local shading, shadows, reflections and refractions. the major disadvantage of ray tracing results from its point-sampling approach. because calculation proceeds ab initio at each pixel it is very cpu intensive and may contain noticeable aliasing artifacts. it is difficult to take advantage of spatial coherence because the shapes of reflections and refractions from curved surfaces are so complex.  in this paper we describe an algorithm that utilizes the spatial coherence of polygonal environments by combining features of both image and object space hidden surface algorithms. instead of tracing infinitesimally thin rays of light, we sweep areas through a scene to form "beams." this technique works particularly well for polygonal models since for this case the reflections are linear transformations, and refractions are often approximately so.  the recursive beam tracer begins by sweeping the projection plane through the scene. beam-surface intersections are computed using two- dimensional polygonal set operations and an occlusion algorithm similar to the weiler- atherton hidden surface algorithm. for each beam-polygon intersection the beam is fragmented and new beams created for the reflected and transmitted swaths of light. these sub-beams are redirected with a 4×4 matrix transformation and recursively traced. this beam tree is an object space representation of the entire picture.  since the priority of polygons is pre-determined, the final picture with reflections, refractions, shadows, and hidden surface removal is easily drawn. the coherence information enables very fast scan conversion and high resolution output. image space edge and texture antialiasing methods can be applied.  paul s. heckbert pat hanrahan
efficient ray tracing of volume data  volume rendering is a technique for visualizing sampled scalar or vector fields of three spatial dimensions without fitting geometric primitives to the data. a subset of these techniques generates images by computing 2-d projections of a colored semitransparent volume, where the color and opacity at each point are derived from the data using local operators. since all voxels participate in the generation of each image, rendering time grows linearly with the size of the dataset. this paper presents a front-to-back image-order volume-rendering algorithm and discusses two techniques for improving its performance. the first technique employs a pyramid of binary volumes to encode spatial coherence present in the data, and the second technique uses an opacity threshold to adaptively terminate ray tracing. although the actual time saved depends on the data, speedups of an order of magnitude have been observed for datasets of useful size and complexity. examples from two applications are given: medical imaging and molecular graphics.  marc levoy
a new formalism for discrete event simulation  a new formalism for discrete event simulation is proposed based on the theoretical frameworks used for the formal analysis and specification of the different aspects of computer languages. the major elements of such a formalism are identified, defined, and discussed. this formalism includes the specification and validation of the structural and behavioral aspects of models specified in it. in this formalism, the behavioral specifications can be used to synchronize different components of a model. this enhances the modeling methodology.  ashvin radiya robert g. sargent
using graphics to build simulation models  computer graphics has become a very important part of the model development process at eaton-kenway. data entry is aided greatly by user friendly software that takes almost all of the work out of building a data base. model validity is determined in less time and customer validation has become much easier. this has resulted in more customers wanting to have models built and increased material handling and factory automation sales. efforts are underway to incorporate cad hardware being used by engineering into the modeling process.  merriel c. dewsnup
object representation by means of nonminimal division quadtrees and octrees  quadtree representation of two-dimensional objects is performed with a tree that describes the recursive subdivision of the more complex parts of a picture until the desired resolution is reached. at the end, all the leaves of the tree are square cells that lie completely inside or outside the object. there are two great disadvantages in the use of quadtrees as a representation scheme for objects in geometric modeling system: the amount of memory required for polygonal objects is too great, and it is difficult to recompute the boundary representation of the object after some boolean operations have been performed. in the present paper a new class of quadtrees, in which nodes may contain zero or one edge, is introduced. by using these quadtrees, storage requirements are reduced and it is possible to obtain the exact backward conversion to boundary representation. algorithms for the generation of the quadtree, boolean operations, and recomputation of the boundary representation are presented, and their complexities in time and space are discussed. three- dimensional algorithms working on octrees are also presented. their use in the geometric modeling of three-dimensional polyhedral objects is discussed.  d. ayala p. brunet r. juan i. navazo
alternatives for modeling of preemptive scheduling  a system which includes overt instances of preemptive scheduling, or which requires the use of preemptive scheduling to model the system, can pose difficulties to a modeler. by preemptive scheduling we mean having to reschedule or cancel a previously scheduled event (or activity completion). the difficulties in modeling preemptive scheduling stem from the highly stylized constructs which simulation languages provide for such operations. this paper describes these difficulties, reviews an approach which can reduce the difficulties for some applications, and presents an approach which can be used to model preemptive scheduling, using only simple simulation language constructs.  james o. henriksen
conservative visibility preprocessing using extended projectionsvisualization of very complex scenes can be significantly accelerated usingocclusion culling. in this paper we present a visibility preprocessing methodwhich efficiently computes potentially visible geometry for volumetric viewingcells. we introduce novel extended projection operators, which permitsefficient and conservative occlusion culling with respect to all viewpointswithin a cell, and takes into account the combined occlusion effect ofmultiple occluders. we use extended projection of occluders onto a set ofprojection planes to create extended occlusion maps; we show how toefficiently test occludees against these occlusion maps to determine occlusionwith respect to the entire cell. we also present an improved projectionoperator for certain specific but important configurations. an importantadvantage of our approach is that we can re-project extended projections ontoa series of projection planes (via an occlusion sweep), and accumulateocclusion information from multiple blockers. this new approach allows thecreation of effective occlusion maps for previously hard-to-treat scenes suchas leaves of trees in a forest. graphics hardware is used to accelerate boththe extended projection and reprojection operations. we present a completeimplementation demonstrating significant speedup with respect to view-frustumculling only, without the computational overhead of on-line occlusion culling.fredo durand george drettakis joÃ"lle thollot claude puech