waashk/acm huggingface dataset:
smooth invariant interpolation of rotations  we present an algorithm for generating a twice-differentiable curve on the rotation group so(3) that interpolated a given ordered set of rotation matrices at their specified knot times. in our approach we regard so(3) as a lie group with a bi-invariant riemannian metriac, and apply the coordinate- invariant methods of riemannian geometry. the resulting rotation curve is easy to compute, invariant with respect to fixed and moving reference frames, and also approximately minimizes angular acceleration.  f. c. park bahram ravani
animated conversation: rule-based generation of facial expression, gesture & spoken intonation for multiple conversational agents  we describe an implemented system which automatically generates and animates conversations between multiple human-like agents with appropriate and synchronized speech, intonation, facial expressions, and hand gestures. conversation is created by a dialogue planner that produces the text as well as the intonation of the utterances. the speaker/listener relationship, the text, and the intonation in turn drive facial expressions, lip motions, eye gaze, head motion, and arm gestures generators. coordinated arm, wrist, and hand motions are invoked to create semantically meaningful gestures. throughout we will use examples from an actual synthesized, fully animated conversation.  justine cassell catherine pelachaud norman badler mark steedman brett achorn tripp becket brett douville scott prevost matthew stone
configuration management for multi-agent systems  as heterogeneous distributed systems, multi-agent systems present some challenging configuration management issues. there are the problems of knowing how to allocate agents to computers, launch them on remote hosts, and once the agents have been launched, how to monitor their runtime status so as to manage computing resources effectively.  in this paper, we present the retsina configuration manager, \emph{recoma}. we describe its architecture, how it uses agent infrastructure such as service discovery, to assist the multi-agent system administrator in allocating, launching, and monitoring a heterogeneous distributed agent system in a distributed and networked computing environment.\footnote{the authors would like to acknowledge the significant contributions of matthew w. easterday in his earlier and exhaustive implementations of configuration management programs and cm design proposals. this research has been sponsored in part by darpa grant f-30602-98-2-0138 and the office of naval research grant n-00014-96-16-1-1222.}  joseph a. giampapa octavio h. juarez-espinosa katia p. sycara
clustering for glossy global illumination  we present a new clustering algorithm for global illumination in complex environments. the new algorithm extends provious work on clustering for radiosity to allow for nondiffuse (glossy) reflectors. we represent clusters as points with directional distributions of outgoing and incoming radiance and importance, and we derive an error bound for transfers between these clusters. the algorithm groups input surfaces into a hierarchy of clusters, and then permits clusters to interact only if the error bound is below an acceptable tolerance. we show that the algorithm is asymptotically more efficient than previous clustering algorithms even when restricted to ideally diffuse environments. finally, we demonstrate the performance of our method on two complex glossy environments.  per h. christensen dani lischinski eric j. stollnitz david h. salesin
an algorithm and data structure for 3d object synthesis using surface patch intersections  there are several successful systems that provide algorithms that allow for the intersection of polygonal objects or other primitive shapes to create more complex objects. our intent is to provide similar algorithms for intersecting surface patches. there have been contributions to this concept at the display algorithm level, that is, computing the intersection at the time the frame is generated. in an animation environment, however, it becomes important to incorporate the intersection in the data generation routines, in order that those parts of the intersected object that never contribute to an image are not processed by the display algorithm. this only increases the complexity of the object unnecessarily, and subsequently puts an additional burden on the display algorithms.  an algorithm is described which uses a modified catmull recursive subdivision scheme to find the space curve which is the intersection of two bicubic patches. an associated data structure is discussed which incorporates this curve of intersection in the patch description in a way suitable for efficient display of the intersected object. sample output of these intersections are shown which serve to illustrate the capabilities and limitations of the described procedures.  wayne e. carlson
extending the radiosity method to include specularly reflecting and translucent materials  an extension of the radiosity method is presented that rigorously accounts for the presence of a small number of specularly reflecting surfaces in an otherwise diffuse scene, and for the presence of a small number of specular or ideal diffuse transmitters. the relationship between the extended method and earlier radiosity and ray-tracing methods is outlined. it is shown that all three methods are based on the same general equation of radiative transfer. a simple superposition of the earlier radiosity and ray-tracing methods in order to account for specular behavior is shown to be physically inconsistent, as the methods are based on different assumptions. specular behavior is correctly included in the present method. the extended radiosity method and example images are presented.  holly e. rushmeier kenneth e. torrance
reconstruction and representation of 3d objects with radial basis functions  we use polyharmonic radial basis functions (rbfs) to reconstruct smooth, manifold surfaces from point-cloud data and to repair incomplete meshes. an object's surface is defined implicitly as the zero set of an rbf fitted to the given surface data. fast methods for fitting and evaluating rbfs allow us to model large data sets, consisting of millions of surface points, by a single rbf --- previously an impossible task. a greedy algorithm in the fitting process reduces the number of rbf centers required to represent a surface and results in significant compression and further computational advantages. the energy-minimisation characterisation of polyharmonic splines result in a "smoothest" interpolant. this scale- independent characterisation is well- suited to reconstructing surfaces from non-uniformly sampled data. holes are smoothly filled and surfaces smoothly extrapolated. we use a non-interpolating approximation when the data is noisy. the functional representation is in effect a solid model, which means that gradients and surface normals can be determined analytically. this helps generate uniform meshes and we show that the rbf representation has advantages for mesh simplification and remeshing applications. results are presented for real-world rangefinder data.
quadrature prefiltering for high quality antialiasing  this article introduces quadrature prefiltering, an accurate, efficient, and fairly simple algorithm for prefiltering polygons for scanline rendering. it renders very high quality images at reasonable cost, strongly suppressing aliasing artifacts. for equivalent rms error, quadrature prefiltering is significantly faster than either uniform or jittered supersampling. quadrature prefiltering is simple to implement and space-efficient; it needs only a small two- dimensional lookup table, even when computing nonradially symmetric filter kernels. previous algorithms have required either three-dimensional tables or a restriction to radially symmetric filter kernels. though only slightly more complicated to implement than the widely used box prefiltering method, quadrature prefiltering can generate images with much less visible aliasing artifacts.  brian guenter jack tumblin
precedent, deontic logic, and inheritance  the purpose of this paper is to establish some connections between precedent- based reasoning as it is studied in the field of artificial intelligence and law, particularly in the work of ashley, and two other fields: deontic logic and nonmonotonic logic. first, a deontic logic is described that allows for sensible reasoning in the presence of conflicting norms. second, a simplified version of ashley's account of precedent-based reasoning is reformulated within the framework of this deontic logic. finally, some ideas from the theory of nonmonotonic inheritance are employed to show how ashley's account might be elaborated to allow for a richer representation of the process of argumentation.  john f. horty
ams: a knowledge-based approach to task representation, organization and coordination  applying artificial intelligence (ai) to the study of office information systems (ois) remains a challenging area. in this paper, we will present a knowledge based approach to modelling office activities. we will focus both on the declarative representation of the office concepts and their relationships, and on the organization of office knowledge in abstract packets, at different levels of generalization. this organization will allow abstract knowledge to be reusable in different situations, and to process and construct concrete structures at different levels. the control structure that should model the behavior of office workers is also discussed.  michel tueni jianzhong li pascal fares
lighting controls for synthetic images  the traditional point source light used for synthetic image generation provides no adjustments other than position, and this severely limits the effects that can be achieved. it can be difficult to highlight particular features of an object. this paper describes new lighting controls and techniques which can be used to optimize the lighting for synthetic images. these controls are based in part on observations of the lights used in the studio of a professional photographer. controls include a light direction to aim a light at a particular area of an object, light concentration to simulate spotlights or floodlights, and flaps or cones to restrict the path of a light. another control relates to the color of the light source and its effect on the perceived color of specular highlights. an object color can be blended with a color for the highlights to simulate different materials, paints, or lighting conditions. this can be accomplished dynamically while the image is displayed, using the video lookup table to approximate the specular color shift  david r. warn
a knowledge-based approach for the validation of simulation models: thefoundationa new perspective of the validation problemfor simulation models is formulatedin this article. the approach is knowledge-based and focuses on behavioralvalidation. it has the important feature of providing a basis for thedevelopment of a software environment that can automate the validationactivity. discrete, continuous and combined simulation models can be treatedin a uniform manner.the key element of the approach is a validation knowledge base (vkb). this isdeveloped as three disjoint sets of relationships among the input and outputvariables of the simulation model. these relationships serve to capture allaspects of expected behavior of the simulation model. a simplecharacterization of model behavior is presented which provides the basis forspecifying the relationships from which the vkb is constructedthe utilization of all the information in the vkb in an efficient way is animportant subgoal of our system architecture. this requirement gives rise toan experiment design problem. this problem is carefully formulated andexamined within the framework of the behavior characterizations that exist inthe vkb. in particular, a basis for its solution is established in aconstraint set framework by carrying out a transformation on the relationshipswithin the vkb. the constraint set context for the problem has the advantageof providing an environment which not only facilitates analysis but alsoenables the application of a variety of solution techniques.louis g. birta f. nur Ã-zmizrak
comparison of surface and derivative evaluation methods for the rendering of nurb surfaces  three methods for evaluating the surface coordinates, first derivatives, and normal vectors of a nurb surface are compared. these methods include forward differencing, knot insertion, and a tow-stage cox-de boor technique. the computational complexity of each of these techniques is analyzed and summarized. the use of hermite functions is shown to yield a poor approximation for the shading functions of a nurb surface. an improved method for computing derivatives by knot insertion is presented. an efficient algorithm for computing the foward difference matrix and a method for using foward differencing to compute the first derivatives of a nurb surface are also presented.  william l. luken fuhua cheng
toward a computational theory of arguing with precedents  this paper presents a partial theory of arguing with precedents in law and illustrates how that theory supports multiple interpretations of a precedent. the theory provides succinct computational definitions of (1) the most persuasive precedents to cite in the principal argument roles and (2) the most salient aspects of the precedents to emphasize when citing them in those roles. an extended example, drawn from the output of the hypo program, illustrates the range of different descriptions of the same precedent that are supported by the theory. each description focuses on different salient aspects of the case depending on the argument context.  k. d. ashley
clustered time warp and logic simulation  we present, in this paper, a hybrid algorithm which makes use of time warp between clusters of lps and a sequential algorithm within the cluster. time warp is, of course, traditionally implemented between individual lps. the algorithm was implemented in a digital logic simulator, and its performance compared to that of time warp.  resting upon this platform we develop a family of three checkpointing algorithms, each of which occupies a different point in the spectrum of possible trade-offs between memory usage and execution time. the algorithms were implemented on several digital logic circuits and their speed, number of states saved and maximal memory consumption were compared to those of time warp. one of the algorithms saved between 35 and 50% of the maximal memory consumed by time warp (depending upon the number of processors used), while the other two decreased the maximal usage up to 30%. the latter two algorithms exhibited a speed comparable to time warp, while the first algorithm was 30-60% slower.  these algorithms are also simpler to implement than optimal checkpointing algorithms.  herve avril carl tropper
prefiltered antialiased lines using half-plane distance functions  we describe a method to compute high-quality antialiased lines by adding a modest amount of hardware to a fragment generator based upon half-plane edge functions. (a fragment contains the information needed to paint one pixel of a line or a polygon.) we surround an antialiased line with four edge functions to create a long, thin, rectangle. we scale the edge functions so that they compute signed distances from the four edges. at each fragment within the antialiased line, the four distances to the fragment are combined and the result indexes an intensity table. the table is computed by convolving a filter kernel with a prototypical line at various distances from the line's edge. because the convolutions aren't performed in hardware, we can use wider, more complex filters with better high-frequency rejection than the narrow box filter common to supersampling antialiasing hardware. the result is smoother antialiased lines.  our algorithm is parameterized by the line width and filter radius. these parameters do not affect the rendering algorithm, but only the setup of the edge functions. our algorithm antialiases line endpoints without special handling. we exploit this to paint small blurry squares as approximations to small antialiased round points. we do not need a different fragment generator for antialiased lines, and so can take advantage of all optimizations introduced in the existing fragment generator.  robert mcnamara joel mccormack norman p. jouppi
computer graphics in commercial and broadcast production (panel)  the goal of this panel is to acquaint the listener with what is perhaps the most visible area of computer graphics - the use of animation in television and motion pictures  creating animation for commercial use is subject to many factors outside of the animator's control. pieces are constrained by deadlines and budgets and yet must be " new, fresh and different" in order to satisfy the client. the speakers on the panel represent four of the leading computer animation production houses and are well acquainted with having to work with these constraints while still delivering work of the highest possible quality. in addition to showing some of their work, the participants will discuss methods for creating animation for commercial use.  carl rosendahl
spiraling edge: fast surface reconstruction from partially organized sample points  many applications produce three-dimensional points that must be further processed to generate a surface. surface reconstruction algorithms that start with a set of unorganized points are extremely time-consuming. sometimes, however, points are generated such that there is additional information available to the reconstruction algorithm. we present spiraling edge, a specialized algorithm for surface reconstruction that is three orders of magnitude faster than algorithms for the general case. in addition to sample point locations, our algorithm starts with normal information and knowledge of each point's neighbors. our algorithm produces a localized approximation to the surface by creating a star-shaped triangulation between a point and a subset of its nearest neighbors. this surface patch is extended by locally triangulating each of the points along the edge of the patch. as each edge point is triangulated, it is removed from the edge and new edge points along the patch's edge are inserted in its place. the updated edge spirals out over the surface until the edge encounters a surface boundary and stops growing in that direction, or until the edge reduces to a small hole that is filled by the final triangle.  patricia crossno edward angel
menu planning by an expert (abstract only)  the development of an expert menu planning system using the database management system ingres and the programming language "c" is presented. there are many factors involved in menu planning that tend to make the dietitian's job tedious and long. therefore, the overall goal of the system is to generate menus for an individual (taking into account his particular nutrient requirements and preferences) in a more efficient and accurate manner than when done manually by the nutritionist. there are five phases involved in developing an expert system [1] : problem identification, conceptualization, formalization, implementation, and testing. these phases encompass such things as: defining the characteristics of the problem, choosing an appropriate knowledge representation scheme, selecting a knowledge engineering tool, building a prototype system, refining the system, and evaluating the final product. each phase will be addressed to explain the actual implementation of the menu planning system. [1] b.g. buchanan et al. "constructing an expert system." in f. hayes-roth et al. eds., building expert systems. reading, massachusetts: addison-wesley publishing company, inc., (1983) 127  kim a. mcmahon
an overview of knowledge representation  this is a brief overview of terminology and issues related to knowledge representation (here-after kr) research, intended primarily for researchers working on semantic data models within database management and program specifications within programming languages/software engineering.  knowledge representation is a central problem in artificial intelligence (ai) today. its importance stems from the fact that the current design paradigm for "intelligent" systems stresses the need for expert knowledge in the system along with associated knowledge-handling facilities. this paradigm is in sharp contrast to earlier ones which might be termed "power-oriented" [goldstein and papert 77] in that they placed an emphasis on general purpose heuristic search techniques [nilsson 71].  john mylopoulos
digital simulation for energy conservation in a large wind tunnel plant system  this paper documents a feasibility study of mathematically modeling the wind tunnel complex and associated plant in the von karman gas dynamics facility at the air force's arnold engineering development center in tennessee. the ultimate goal of the modeling effort is to effect energy conservation measures by modifying operational procedures and plant hardware. a general theory is proposed to model the aerodynamics and losses of each plant or tunnel component in terms of a set of 33 equations based on one-dimensional, unsteady, nonisentropic flow and admitting arbitrary interconnections between components. a computer program is currently under development to apply the theoretical model using the ibm continuous system modeling program iii. in conjunction with the modeling effort, an assessment was made of the existing experimental data base which could be used to drive the mathematical model. requirements for experimental data are discussed in general terms.  frederick l. shope
simulation with c  the c programming language was developed at bell laboratories in 1972 by dennis ritchie. since that time, c has had major acceptance as a modern programming language suitable for a large variety of applications. those applications include the operating system unix, which was written in c for portability. it requires only a c compiler and the rewriting of some low level routines in machine language for implementation on virtually any computer. the best documentation of c is provided in a book entitled the c programming language by kerninghan and ritchie.[1]  this paper explores the use of c as the host language for discrete event simulation. one of the primary motivators is the portability of c code. c compilers are now available for a variety of computers from microcomputers to mainframes. hence, a simulation model developed in c could execute on a microcomputer or a mainframe, given a standard c compiler. the standard for c is well defined via compilers which have a full implementation of c. kerningham and ritchie's text provides the documentation for that standard.  floyd h. grant douglas g. macfarland
a frame buffer system with enhanced functionality  a video-resolution frame buffer system with 32 bits per pixel is described. the system includes, in addition to standard features for limited zoom and pan, an arithmetic unit at the update port which allows local computation of many frequently-used pixel-level functions combining stored pixel values with incoming pixel values. in addition to the standard arithmetic and logical functions there are functions for sum to maximum pixel value and difference to minimum pixel value. comparisons between incoming and stored data are used to implement conditional writes based on depth values for depth-buffer algorithms. update and refresh ports are designed for a wide range of flexibility allowing simultaneous use by separate tasks and various functional rearrangements of the 32-bit pixel words. the memory architecture, refresh and update ports are described. examples of widely divergent modes of operation are provided.  f. c. crow m. w. howard