waashk/acm huggingface dataset:
shading models for point and linear sources  the degree of realism of the shaded image of a tree-dimensional scene depends on the successful simulation of shading effects. the shading model has two main ingredients, properties of the surface and properties of the illumination falling on it. most previous work has concentrated on the former rather than the latter.  this paper presents an improved version for generating scenes illuminated by point and linear light sources. the procedure can include intensity distributions for point light sources and output both umbrae and penumbrae for linear light sources, assuming thr environment is composed of convex polyhedra. this paper generalizes crow's procedure for computing shadow volumes caused by the end points of the linear source results in an easy determination of the reions of penumbrae and umbrae on the face prior to shading calculation.  this paper also discusses a method for displaying illuminance distribution on a shaded image aby using colored isolux contours.  tomoyuki nishita isao okamura eihachiro nakamae
displacement mapping using flow fields  existing displacement mapping techniques operate only in directions normal to the surface, a restriction which limits the richness of the set of representable objects. this work removes that restriction by allowing displacements to be defined along curved trajectories of flow fields. the main contribution of this generalized technique, which will be referred to as flow mapping, is an alternative model of offset surfaces that extends the class of shapes that can be modelled using displacement maps. the paper also discusses methods for synthesizing homogeneous displacement textures. finally, it introduces the concept of a texture atlas for efficient sampling and reconstruction of distorted textures.  hans køhling pedersen
a physically-based night sky model  this paper presents a physically- based model of the night sky for realistic image synthesis. we model both the direct appearance of the night sky and the illumination coming from the moon, the stars, the zodiacal light, and the atmosphere. to accurately predict the appearance of night scenes we use physically-based astronomical data, both for position and radiometry. the moon is simulated as a geometric model illuminated by the sun, using recently measured elevation and albedo maps, as well as a specialized brdf. for visible stars, we include the position, magnitude, and temperature of the star, while for the milky way and other nebulae we use a processed photograph. zodiacal light due to scattering in the dust covering the solar system, galactic light, and airglow due to light emission of the atmosphere are simulated from measured data. we couple these components with an accurate simulation of the atmosphere. to demonstrate our model, we show a variety of night scenes rendered with a monte carlo ray tracer.  henrik wann jensen fredo durand julie dorsey michael m. stark peter shirley simon premoze
a theory of the learnable  humans appear to be able to learn new concepts without needing to be programmed explicitly in any conventional sense. in this paper we regard learning as the phenomenon of knowledge acquisition in the absence of explicit programming. we give a precise methodology for studying this phenomenon from a computational viewpoint. it consists of choosing an appropriate information gathering mechanism, the learning protocol, and exploring the class of concepts that can be learnt using it in a reasonable (polynomial) number of steps. we find that inherent algorithmic complexity appears to set serious limits to the range of concepts that can be so learnt. the methodology and results suggest concrete principles for designing realistic learning systems.  l. g. valiant
irex: an expert system for the selection of industrial robots and its implementation in two environments  this paper describes the design and implementation of a prototype robot selection expert system based on an outside/in approach. the expert system is comprised of three basic parts. the first part examines several proposed applications where automation is desired and chooses the one best suited for automation using a robot. the second part uses rules to select the configuration, drive, programming type, and playback type. the third section of the expert system examines a data base of robots and selects the best five robots for the application based on the users specifications of that job. the paper describes its implementation in kee and the expert system's transfer to the keystone environment on a ps-2 model 80.  b. a. gardone r. k. ragade
analysis of a heuristic for full trie minimization  a trie is a distributed-key search tree in which records from a file correspond to leaves in the tree. retrieval consists of following a path from one root to a leaf, where the choice of edge at each node is determined by attribute values of the key. for full tries, those in which all leaves lie at the same depth, the problem of finding an ordering of attributes which yields a minimum size trie is np-complete.  this paper considers a "greedy" heuristic for constructing low-cost tries. it presents simulation experiments which show that the greedy method tends to produce tries with small size, and analysis leading to a worst case bound on approximations produced by the heuristic. it also shows a class of files for which the greedy method may perform badly, producing tries of high cost.  douglas comer
mixing translucent polygons with volumes  we present an algorithm which renders opaque and/or translucent polygons embedded within volumetric data. the processing occurs such that all objects are composited in the correct order, by rendering thin slabs of the translucent polygons between volume slices using slice-order volume rendering. we implemented our algorithm with opengl on current general-purpose graphics systems. we discuss our system implementation, speed and image quality, as well as the renderings of several mixed scenes.  kevin kreeger arie kaufman
a system for algorithm animation  a software environment is described which provides facilities at a variety of levels for "animating" algorithms: exposing properties of programs by displaying multiple dynamic views of the program and associated data structures. the system is operational on a network of graphics-based, personal workstations and has been used successfully in several applications for teaching and research in computer science and mathematics. in this paper, we outline the conceptual framework that we have developed for animating algorithms, describe the system that we have implemented, and give several examples drawn from the host of algorithms that we have animated.  marc h. brown robert sedgewick
image-based rendering of diffuse, specular and glossy surfaces from a single image  in this paper, we present a new method to recover an approximation of the bidirectional reflectance distribution function (brdf) of the surfaces present in a real scene. this is done from a single photograph and a 3d geometric model of the scene. the result is a full model of the reflectance properties of all surfaces, which can be rendered under novel illumination conditions with, for example, viewpoint modification and the addition of new synthetic objects. our technique produces a reflectance model using a small number of parameters. these parameters nevertheless approximate the brdf and allow the recovery of the photometric properties of diffuse, specular, isotropic or anisotropic textured objects. the input data are a geometric model of the scene including the light source positions and the camera properties, and a single image captured using this camera. our algorithm generates a new synthetic image using classic rendering techniques, and a lambertian hypothesis about the reflectance model of the surfaces. then, it iteratively compares the original image to the new one, and chooses a more complex reflectance model if the difference between the two images is greater than a user-defined threshold.  we present several synthetic images that are compared to the original ones, and some possible applications in augmented reality.
construction of vector field hierarchies  we present a method for the hierarchical representation of vector fields. our approach is based on iterative refinement using clustering and principal component analysis. the input to our algorithm is a discrete set of points with associated vectors. the algorithm generates a top-down segmentation of the discrete field by splitting clusters of points. we measure the error of the various approximation levels by measuring the discrepancy between streamlines generated by the original discrete field and its approximations based on much smaller discrete data sets. our method assumes no particular structure of the field, nor does it require any topological connectivity information. it is possible to generate multiresolution representations of vector fields using this approach.  bjoern heckel gunther weber bernd hamann kenneth i. joy
distributed simulation with locality  we describe moss, a small language of mobile distributed objects and system- wide references, uncommitted to any distributed simulation protocol, but which can be executed as a distributed conservative simulation with automatic deduction of lookahead. we show how the moss programmer can control the dynamic distribution and locality of simulation objects by simple means which provide natural modelling functions. preliminary results show how programmed locality can reduce communication costs in simulation.  t. d. blanchard t. w. lake
3d position, attitude and shape input using video tracking of hands and lips  recent developments in video-tracking allow the outlines of moving, natural objects in a video-camera input stream to be tracked live, at full video-rate. previous systems have been available to do this for specially illuminated objects or for naturally illuminated but polyhedral objects. other systems have been able to track nonpolyhedral objects in motion, in some cases from live video, but following only centroids or key-points rather than tracking whole curves. the system described here can track accurately the curved silhouettes of moving non-polyhedral objects at frame-rate, for example hands, lips, legs, vehicles, fruit, and without any special hardware beyond a desktop workstation and a video-camera and framestore.  the new algorithms are a synthesis of methods in deformable models, b-splines curve representation and control theory. this paper shows how such a facility can be used to turn parts of the body---for instance, hands and lips---into input devices. rigid motion of a hand can be used as a 3d mouse with non-rigid gestures signalling a button press or the "lifting" of the mouse. both rigid and non-rigid motions of lips can be tracked independently and used as inputs, for example to animate a computer-generated face.  andrew blake michael isard
free-form shape design using triangulated surfaces  we present an approach to modeling with truly mutable yet completely controllable free-form surfaces of arbitrary topology. surfaces may be pinned down at points and along curves, cut up and smoothly welded back together, and faired and reshaped in the large. this style of control is formulated as a constrained shape optimization, with minimization of squared principal curvatures yielding graceful shapes that are free of the parameterization worries accompanying many patch-based approaches. triangulated point sets are used to approximate these smooth variational surfaces, bridging the gap between patch-based and particle-based representations. automatic refinement, mesh smoothing, and re- triangulation maintain a good computational mesh as the surface shape evolves, and give sample points and surface features much of the freedom to slide around in the surface that oriented particles enjoy. the resulting surface triangulations are constructed and maintained in real time.  william welch andrew witkin
analogical reasoning in planning and decision making  analogical reasoning is a significant cognitive process that has heretofore not been modelled by artificial intelligence researchers in a computationally tractable manner. recently, several new approaches have shown significant promise using analogical processes for problem solving and learning. among the first and most comprehensive, the aries project demonstrated that analogical problem solving is a computationally tractable means of exploiting past experience to solve new problems of increasing complexity. two methods were developed: transformational analogy, with solutions to related problems are incremently transformed into the solution of a new problem, and derivational analogy with the problem solving strategies, rather than the resultant solutions, are transferred across like problems.  however, many interesting questions remain unanswered, including: how closely related should problems be prior to analogical transfer? how does one measure similarity? what is the relation of analogical transfer to human problem solving capabilities? what roles does analogy play in learning? should analogical reasoning be part of a decision analysis engine to bring past experience to bear in evaluating likely consequences of candidate decisions? should analogical reasoning be considered an integral aspect of any unified problem solving architecture striving to model human cognition? after a glimpse into the basic aries model, partial answers to these questions are discussed based on recent advances. some of these new directions are rooted in concrete computational and psychological results; others are of a more speculative nature.  j carbonell
the view from the trenches: issues in the ontology of restricted domains we consider the impact of strict processing limitations on thedesign of an ontology for information extraction from newswiretexts. we conclude that requiring online, real-time processingleads to a particular set of answers to fundamental issues ofrelation size and the choice of primary categories. we show how tosatisfy these requirements by using relational categories directlyduring analysis and by using a reified lattice of their partialsaturations that is annotated with the linguistic constructs usedto realize them. david d. mcdonald
anti-aliased line drawing using brush extrusion  this algorithm draws lines on a gray-scale raster display by dragging a "brush" along the path of the line. the style of the line is determined by the properties of the brush. an anti-aliasing calculation is performed once for the brush itself and thereafter only a trivial additional operation is needed for each pixel through which the brush is dragged to yield an anti-aliased line.  there are few constraints on the size, shape, and attributes of the brush. lines can be curved as well as straight, it is possible to produce lines with a three dimensional appearance.  turner whitted
a learning technique for legal document analysis  more and more law is available freely on the internet. the growing complexity of legal rules and the necessary adaptation to user needs requires better instruments than manual browsing and searching interfaces of the past. information reconnaissance of an unknown text corpus would provide a major help. our research on neural networks concerns adaptive learning techniques for information reconnaissance in legal document archives. self-organising maps offer besides successful classification a promising tool for this purpose. the neural processing elements can be labeled with the most appropriate keywords to describe the contents of the documents. applying the tools of refinement, our novel approach describes the most interesting features of the document. the user can choose properly between the various units in order to refine the next step of research. an integration of this tool of information reconnaissance into an intelligent agent is straightforward and will bring much benefit in a practical application.  erich schweighofer dieter merkl
a visible polygon reconstruction algorithm  an algorithm for determining visible lines or visible surfaces in polygonal form, at object resolution, is presented. the original scene must consist of non-intersecting planar polygons. the procedure relies on image coherence, since the sampling is dependent on the complexity of the image. the reconstruction method is based on an elaborate data structure, which allows the polygonal output to be easily obtained. the polygonal output is useful for smooth shaded or textured images, as well as the for creation of shadows.  stuart sechrest donald p. greenberg
artificial intelligence and simulation: an introduction  artificial intelligence is one of the most rapidly developing fields in modern applied computer science. it has generated research and applications in several widely varying fields, both within and without the realm of topics considered to be 'core' ai components. at the same time, the science of simulation modelling is also advancing steadily, incorporating new technologies such as graphical output display and more recently, applications of artificial intelligence.  this paper provides a brief description of the major component topics of artificial intelligence. several references are included to allow readers to examine topics of interest in more depth. the paper also discusses the application of intelligent systems to simulation modelling and describes, with references, some of the development in this area to date.  r. greer lavery
efficient agnostic pac-learning with simple hypothesis  we exhibit efficient algorithms for agnostic pac-learning with rectangles, unions of two rectangles, and unions of k intervals as hypotheses. these hypothesis classes are of some interest from the point of view of applied machine learning, because empirical studies show that hypotheses of this simple type (in just one or two of the attributes) provide good prediction rules for various real-world classification problems. in addition, optimal hypotheses of this type may provide valuable heuristic insight into the structure of a real world classification problem.  the algorithms that are introduced in this paper make it feasible to compute optimal hypotheses of this type for a training set of several hundred examples. we also exhibit an approximation algorithm that can compute nearly optimal hypotheses for much larger datasets.  wolfgang maass
pen: a hierarchical document editor  three terms in common usage in computerized text processing are text-editing, word- processing, and computer controlled typesetting. this paper deals with a fourth term, manuscript preparation, that has important intersections with the above three. a computerized manuscript preparation system is one that supports an author in the preparation of a manuscript. in what follows we deal with one such, the pen system, directed towards the preparation of manuscripts containing significant mathematical notation.  todd allen robert nix alan perlis
software agents and intelligent object fusion techniques for modular software design are presented applying _software agents._ the conceptual designs are domain independent and make use of specific domain aspects applying _multiagent ai._ the stages of conceptualization, design and implementation are defined by new techniques coordinated by objects. software systems are designed by knowledge acquisition, specification, and multiagent implementations. multiagent implementations are defined for the modular designs, applying our recent projects which have lead to fault tolerant ai systems. a novel multi-kernel design technique is presented.communicating pairs of kernels, each defining a part of the system, are specified by object- coobject super-modules. treating objects as abstract data types and a two level programming approach to oop allows us to define pull-up abstractions to treat incompatible objects. **keywords** abstract objects, intelligent syntax, mjoop, multi agent object level programming, multi kernel design with oop, software agents, intelligent objects. academic ucsb when at university cyrus f. nourani
crogro: an interactive forest growth simulator  crogro is an interactive computer model which simulates crown growth in trees as they compete with each other for available space and light. the model contains growth data for six species of trees. crogro was designed to be used as a teaching aid. it allows forestry students to observe in a few minutes a process which, in the real world, occurs over several decades. the system is programmed in apl and input/output is via a tektronix 4015 graphics display terminal.  d. m. fellows g. l. sprague g. l. baskerville
modeling a genetic control program for the tobacco budworm with slam  a simulation model is described and used to investigate the potential for controlling the tobacco budworm through hybrid sterilization. the results indicated that high levels of population control appear feasible with relatively large release ratios. however, driving population levels to zero may be ruled out by such factors as different egg laying capabilities between budworm and backcross moths and by in-migration of budworm moths.  a general slam insect model is also described and developed which may be of value to other researchers studying population dynamics. the authors were well satisfied with the capabilities of slam.  richard a. levins murl wayne parker
introduction to demos  demos [1,2] is yet another discrete event simulation language hosted in simula. it was released in 1979 and is now running on ibm, dec, univac, and cdc hardwares amongst others. the paper contains a short introduction to simula's object and context features; an explanation of the process approach to simulation; a brief comparison of simula and gpss; and finally, the main features of demos are presented via an example.  graham birtwistle
synthetic texturing using digital filters  aliasing artifacts are eliminated from computer generated images of textured polygons by equivalently filtering both the texture and the edges of the polygons. different filters can be easily compared because the weighting functions that define the shape of the filters are pre-computed and stored in lookup tables. a polygon subdivision algorithm removes the hidden surfaces so that the polygons are rendered sequentially to minimize accessing the texture definition files. an implementation of the texture rendering procedure is described.  eliot a. feibush marc levoy robert l. cook
selecting the checkpoint interval in time warp simulation  in time warp parallel simulation, the state of each process must be saved (checkpointed) regularly in case a rollback is necessary. although most existing time warp implementations checkpoint after every state transition, this is not necessary, and the checkpoint interval is in reality a tuning parameter of the simulation.  lin and lazowska[6] proposed a model to derive the optimal checkpoint interval by assuming that the rollback behavior of time warp is not affected by the frequency of checkpointing. an experimental study conducted by preiss et al.[10] indicates that the behavior of rollback is affected by the frequency of checkpointing in general, and that the lin-lazowska model may not reflect the real situations in general.  this paper extends the lin-lazowska model to include the effect of the checkpoint interval on the rollback behavior. the relationship among the checkpoint interval, the rollback behavior, and the overhead associated with state saving and restoration is described. a checkpoint interval selection algorithm which quickly determines the optimal checkpoint interval during the execution of time warp simulation is proposed. empirical results indicate that the algorithm converges quickly and always selects the optimal checkpoint interval.  yi-bing lin bruno r. preiss wayne m. loucks edward d. lazowska