waashk/acm huggingface dataset:
improving static and dynamic registration in an optical see-through hmd  in augmented reality, see-through hmds superimpose virtual 3d objects on the real world. this technology has the potential to enhance a user's perception and interaction with the real world. however, many augmented reality applications will not be accepted until we can accurately register virtual objects with their real counterparts. in previous systems, such registration was achieved only from a limited range of viewpoints, when the user kept his head still. this paper offers improved registration in two areas. first, our system demonstrates accurate static registration across a wide variety of viewing angles and positions. an optoelectronic tracker provides the required range and accuracy. three calibration steps determine the viewing parameters. second, dynamic errors that occur when the user moves his head are reduced by predicting future head locations. inertial sensors mounted on the hmd aid head-motion prediction. accurate determination of prediction distances requires low-overhead operating systems and eliminating unpredictable sources of latency. on average, prediction with inertial sensors produces errors 2-3 times lower than prediction without inertial sensors and 5-10 times lower than using no prediction at all. future steps that may further improve registration are outlined.  ronald azuma gary bishop
the a -buffer, an antialiased hidden surface method  the a-buffer (anti-aliased, area-averaged, accumulation buffer) is a general hidden surface mechanism suited to medium scale virtual memory computers. it resolves visibility among an arbitrary collection of opaque, transparent, and intersecting objects. using an easy to compute fourier window (box filter), it increases the effective image resolution many times over the z-buffer, with a moderate increase in cost. the a-buffer is incorporated into the reyes 3-d rendering system at lucasfilm and was used successfully in the "genesis demo" sequence in star trek ii.  loren carpenter
depth-order point classification techniques for csg display algorithms  constructive solid geometry (csg) defines objects as boolean combinations (csg trees) of primitive solids. to display such objects, one must classify points on the surfaces of the primitive solids with respect to the resulting composite object, to test whether these points lie on the boundary of the composite object or not. although the point classification is trivial compared to the surface classification (i.e., the computation of the composite object), for csg models with a large number of primitive solids (large csg trees), the point classification may still consume a considerable fraction of the total processing time. this paper presents an overview of existing and new efficiency-improving techniques for classifying points in depth order. the different techniques are compared through experiments.  frederik w. jansen
emacs the extensible, customizable self-documenting display editor  emacs is a display editor which is implemented in an interpreted high level language. this allows users to extend the editor by replacing parts of it, to experiment with alternative command languages, and to share extensions which are generally useful. the ease of extension has contributed to the growth of a large set of useful features. this paper describes the organization of the emacs system, emphasizing the way in which extensibility is achieved and used.  this report describes work done at the artificial intelligence laboratory of the massachusetts institute of technology. support for the laboratory's research is provided in part by the advanced research projects agency of the department of defense under office of naval research contract n00014-80-c-0505.  richard m. stallman
knowledge-based understanding on a small machine  one problem plaguing current knowledge-based systems is the acquisition of the information that is represented in the knowledge base. most knowledge processing systems, such as expert systems and more recent case-based systems, are either based on static data that has already been entered into the system, or use human intervention to enter the information into the system in the correct format. both of these methods greatly reduce the power and flexibility of the system since, presumably, an intelligent knowledge-based system would make better decisions provided with more information. one resource that provides a vast amount of information is written text, such as journals, newspapers and on-line news wires. systems that use information provided by such resources could greatly benefit if they automatically acquired this information. this paper presents research directed at the development of such a system on a small machine.  benjamin moreland
modeling and rendering waves: wave-tracing using beta-splines and reflective and refractive texture mapping.  the graphical simulation of a certain subset of hydrodynamics phenomena is examined. new algorithms for both modeling and rendering these complex phenomena are presented.  the modeling algorithms deal with wave refraction in an ocean. waves refract in much the same way as light. in both cases, the equation that controls the change in direction is snell's law. ocean waves are continuous but can be discretely decomposed into wave rays or wave orthogonals. these wave orthogonals are wave-traced in a manner similar to the rendering algorithm of ray-tracing. the refracted wave orthogonals are later traversed and their height contributions to the final surface are calculated using a sinusoidal shape approximation and the principle of wave superposition. the surface is then represented by beta-splines, using the tension (or β2) shape parameter to easily add more complexity to the surface.  the rendering algorithms are based on the use of texture maps and fresnel's law of reflection. in each algorithm, two texture maps are used to simulate reflection and refraction. based on surface normal orientation and fresnel's law, a weighting is calculated that determines what fractions of reflected color and refracted color are assigned to a point. these algorithms are more efficient, though less accurate, alternatives to standard ray-tracing techniques.  pauline y. ts'o brian a. barsky
system-level simulation of a next generation, multi-sensor concurrent signal processor  a new generation of processors is now emerging which addresses the modular processing requirements for a wide range of multispectrum applications envisioned for the late-20th/early-21st century. due to the complexity of interaction among software modules and hardware devices simulation techniques are required to verify that specific configurations support application requirements. this paper demonstrates how simulation results can provide useful information for validation objectives. for this study, a system-level architectural model of one such processor was written in a conventional programming language oriented toward simulation of computer environments.  james f. engler
is this a quadrisected mesh?  in this paper we introduce a fast and efficient linear time and space algorithm to detect and reconstruct uniform loop subdivision structure, or triangle quadrisection, in irregular triangular meshes. instead of a naive sequential traversal algorithm, and motivated by the concept of _covering surface_ in algebraic topology, we introduce a new algorithm based on global connectivity properties of the _covering mesh_. we consider two main applications for this algorithm. the first one is to enable interactive modelling systems that support loop subdivision surfaces, to use popular interchange file formats which do not preserve the subdivision structure, such as vrml, without loss at information. the second application is to improve the compression efficiency of existing lossless connectivity compression schemes, by optimally compressing meshes with loop subdivision connectivity. extensions to other popular uniform subdivision schemes such as catmull-clark and doo- sabin, are relatively straightforward but will be studied elsewhere.  gabriel taubin
visualizing large-scale telecommunication networks and services (case study)  visual exploration of massive data sets arising from telecommunication networks and services is a challenge. this paper describes swift-3d, an integrated data visualization and exploration system created at at&amp;t; labs for large scale network analysis. swift-3d integrates a collection of interactive tools that includes pixel-oriented 2d maps, interactive 3d maps, statistical displays, network topology diagrams and an interactive drill-down query interface. example applications are described, demonstrating a successful application to analyze unexpected network events (high volumes of unanswered calls), and comparison of usage of an internet service with voice network traffic and local access coverage.1  eleftherios e. koutsofios stephen c. north russell truscott daniel a. keim
representing teleological structure in case-based legal reasoning: the missing link  we argue that robust case-based models of legal knowledge that represent the way in which practicing professionals use legal decisions must contain a deeper domain model that represents the purposes behind the rules articulated in the cases. we propose a model for representing the teleological components of legal decisions, and we suggest a method for utilizing this representation in a hypo-like framework for case-based legal argument.  donald h. berman carole d. hafner
some observations on modelling case based reasoning with formal argument models  in this paper i shall explore the modelling of case based reasoning using a formal model of argument, taking the approach of prakken and sartor as my starting point. i first consider their method of representing cases, and describe how --- if we restrict ourselves to independent boolean factors --- we can fruitfully model the domain as a partial order on rules. i then consider the issues relating to quantifiable factors, as used in hypo, and factor hierarchies, as used in cato. the former presents some difficulties for modelling as a partial order, and, coupled with the latter, forces us to recognise two different kinds of reasoning used in concept application which have different implications for representing the domain. i then present some conclusions arising from the discussion.  t. j. m. bench-capon
nurbs in vrml  in the days of vrml 1.0, nurbs seemed to be too complex to be adapted to the specification. current development of hardware compels us to reevaluate this idea: while cpu clocks break the 1-ghz barrier, users still have to cope with 56k modems. nurbs meet exactly these demands. a nurbs description is a compact storage form, but its evaluation requires more computational effort. in addition, nurbs can be utilized for morphing effects and they provide a means for a smooth lod. adopting trimmed nurbs allows visualization of complex cad models in vrml. this paper gives an overview of the proposed nodes and their implementation and applications. we take a closer look at lod, animations and trimmed nurbs. finally, we look ahead and briefly touch on an emerging new representation, subdivision surfaces.  holger grahn thomas volk hans j. wolters
sentencing and information management: consistency and the particularities of a case  sentencing practice is often considered inconsistent. the use of it and ai to support sentencing decisions in order to make them more consistent, deserves a lot of attention nowadays. the movement for more fair and consistent sentencing in the netherlands led to the development of several jdsss (judicial decision support system) that already are or shortly will be used by the public prosecution and the judiciary. criticism towards the use of it and ai for this sentencing purpose is often directed at the resulting standardization that tends to overlook individualized sentencing.  in this paper we describe the current situation of computerization in the domain of criminal justice. we address information management within the criminal justice chain (police--- 'public prosecution' \---judge). current practice is evaluated and future developments are addressed.  we argue that information management and electronic versions of case files could help in providing especially the judge with more relevant information. this could lead to effective consult of two main aspects of criminal cases: establishing the facts and obeying procedural rules.  marius j. a. duker arno r. lodder
ports: a parallel, optimistic, real-time simulator  this paper describes issues concerning the design of an optimistic parallel discrete event simulation system that executes in environments that impose real-time constraints on the simulator's execution. two key problems must be addressed by such a system. first the timing characteristics of the parallel simulator must be sufficiently predictable to allow one to guarantee that real-time deadlines for completing simulation computations will be met. second, the optimistic computation must be able to interact with its surrounding environment with as little latency as possible, necessitating rapid commitment of i/o operations.  to address the first question, we show that optimistic simulators that never send incorrect messages (sometimes called "aggressive-no-risk" simulators) provide sufficient predictability to allow traditional schedulability analysis techniques commonly used in real-time systems to be applied. we show that incremental state saving techniques introduce sufficient unpredictability that they are not well-suited for real-time environments. we observe that the traditional "lowest timestamp first" scheduling policy used in many optimistic parallel simulation systems is an optimal (in the real-time sense) scheduling algorithm when event timestamps and real-time deadlines are the same. finally, to address the question for rapid commitment of i/o operations, we utilize a continuous gvt computation scheme for shared- memory multiprocessors where a new value of gvt is computed after processing each event in the simulation.  these ideas are incorporated in a parallel, optimistic, real-time simulation system called ports. initial performance measurements of the shared-memory based ports system executing on a kendall square research multiprocessor are presented. initial performance results are encouraging, demonstrating that ports achieves performance approaching that of a conventional time warp system for the benchmark programs that were tested.  kaushik ghosh richard m. fujimoto karsten schwan
a formal foundation for process modeling process modeling is ubiquitous in business and industry. while agreat deal of effort has been devoted to the formal andphilosophical investigation of processes, surprisingly littleresearch connects this work to real world process modeling. thepurpose of this paper is to begin making such a connection. to doso, we first develop a simple mathematical model of activities andtheir instances based upon the model theory for the nist processspecification language (psl), a simple language for describingthese entities, and a semantics for the latter in terms of theformer, and a set of axioms for the semantics based upon the nistprocess specification language (psl). on the basis of thisfoundation, we then develop a general notion of a process model,and an account of what it is for such a model to be realized by acollection of events. christopher menzel michael gruninger
real-time bump map synthesis  in this paper we present a method that automatically synthesizes bump maps at arbitrary levels of detail in real- time. the only input data we require is a normal density function; the bump map is generated according to that function. it is also used to shade the generated bump map.  the technique allows to infinitely zoom into the surface, because more (consistent) detail can be created on the fly. the shading of such a surface is consistent when displayed at different distances to the viewer (assuming that the surface structure is self- similar).  the bump map generation and the shading algorithm can also be used separately.  jan kautz wolfgang heidrich hans-peter seidel
simulation modeling with insight  using insight, simulation models can be built and evaluated with less time and effort than previously possible. insight defines a vocabulary for systems analysis and provides a small set of modeling symbols to represent the basic processes found in real systems. by combining the symbols graphically and filling in needed information, immediately useful simulation models can be constructed quickly. simple models can be greatly embellished using the rich variety of insight specifications without resorting to any computer programming. the visual model is simply translated into insight statements for automatic execution. procedures incorporated in insight enable sound statistical analysis to be used routinely. such features reduce the cost and difficulty in obtaining representative results. the net result is that attention is focused on modeling and analysis.  stephen d. roberts
a simulation for the justification and planning of a continuous slab caster  two major simulation models were developed to aid in planning the multi- million dollar expansion of steelmaking facilities at bethlehem steel's sparrows point, maryland, plant. one model looks at the flow of liquid metal through steelmaking facilities while the second model represents the handling of solid slabs produced by the new continuous caster.  both simulation models were written using "bethsim", a bethlehem steel developed simulation language used primarily for discrete event simulation. bethsim uses a network combined with user written fortran subroutines and package subroutines that aid in the modeling of complex manufacturing elements such as roller lines, crane movements, and storage areas. output from the models consists of standard bethsim reports and customized reports produced by fortran subroutines and a sas postprocessor.  beverly j. wolfe mark a. christobek
advances in parameter estimation from event count data  in modeling a system, identifying the times at which the state of the system changes is important. in particular, the probability distributions of the interevent times (time lengths between consecutive events) of each process (such as interarrival times) are required in a simulation model. often information characterizing the interevent times may be unavailable or difficult to obtain. on the other hand, the number of event per unit time is simple and economical to collect.  in the last few years, there has been much research in stochastic modeling using point processes by a varied group of researchers. despite this extensive and diverse research effort, little attention has been given to estimation techniques based on event count data rather than event time data. this paper discusses recent advances (in the last year) in estimation based on event count data.  ronald dattero
gnu/maverik: a micro-kernel for large-scale virtual environments  this paper describes a publicly available virtual reality (vr) system, gnu/maverik, which forms one component of a complete 'vr operating system'. we give an overview of the architecture of maverik, and show how it is designed to use application data in an intelligent way, via a simple, yet powerful, callback mechanism which supports an object-oriented framework of classes, objects and methods. examples are given which illustrate different uses of the system, and typical performance levels.  roger hubbold jon cook martin keates simon gibson toby howard alan murta adrian west steve pettifer
an ease of use evaluation of an integrated document processing system  designers of systems intended to be easy to use have many guidelines available to them in the literature. most of these recommendations are based on the intuition and experiences of particular designers with particular systems. very few of them have been evaluated experimentally, so one must be cautious not to attribute more authority to these guidelines than they deserve [6].  this paper summarizes the results of an experimental evaluation of the etude text processing system [8]. section 2 provides a brief overview of etude. section 3 describes the development of suitable ease of use criteria. section 4 presents the experimental protocol. section 5 discusses the results of the evaluation. a complete description of the experiment can be found in [7].  michael good
modeling and simulation in product development  as part of the product development cycle, the xerox corporation has evolved a modeling and simulation methodology. this paper describes the approach, its use, and value in product development. to provide a common basis for understanding the modeling activities to be discussed, a brief overview of the xerographic process as used in our current duplicator copier products is described. each of the functions is discussed in terms of how they contribute to the overall systems model and how they are linked together in this model. a brief description of the data acquisition system used for model validation is included.  a discussion of the fortran-based simulation language, analysis tools, and its flexibility is presented. the application of this modeling approach at xerox is illustrated. the applications are the optimization of performance parameters, subsystem requirements, tolerances, aging, and setpoints, as well as the examination of the performance of a population. these population studies encompass customer utilization and service interactions. the advantages of this process will be discussed, including the design efficiencies enabled, service policy optimization, and field performance projection of the product population.  douglas g. boike edward h. ernst
piks and biif explored this issue's column is an introduction to the image processing and interchange standards (iso/iec 12087) developed by iso/iec jtc i/ sc 24 (computer graphics and image processing.). first, bill pratt of pixelsoft, the editor of the programmer's imaging kernel system (piks) international standard (iso/iec 12087-1:1995), describes piks and how it can be applied. next, i describe the basic image interchange format (biif), iso/iec 12087-1:1998, and its applications. george s. carson william k. pratt
using visual texture for information display  results from vision research are applied to the synthesis of visual texture for the purposes of information display. the literature surveyed suggests that the human visual system processes spatial information by means of parallel arrays of neurons that can be modeled by gabor functions. based on the gabor model, it is argued that the fundamental dimensions of texture for human perception are orientation, size (1/frequency), and contrast. it is shown that there are a number of trade-offs in the density with which information can be displayed using texture. two of these are (1) a trade-off between the size of the texture elements and the precision with which the location can be specified, and (2) the precision with which texture orientation can be specified and the precision with which texture size can be specified. two algorithms for generating texture are included.  colin ware william knight
height distributional distance transform methods for height field ray tracing  height distributional distance transform (hddt) methods are introduced as a new class of methods for height field ray tracing. hddt methods utilize results of height field preprocessing. the preprocessing involves computing a height field transform representing an array of cone-like volumes of empty space above the height field surface that are as wide as possible. there is one cone-like volume balanced on its apex centered above each height field cell. various height field transforms of this type are developed. each is based on distance transforms of height field horizontal cross-sections. hddt methods trace rays through empty cone-like volumes instead of through successive height field cells. the performance of hddt methods is evaluated experimentally against existing height field ray tracing methods.  david w. paglieroni sidney m. petersen