waashk/acm huggingface dataset:
lapped textures  we present for creating texture over an surface mesh using an example 2d texture. the approach is to identify interesting regions (texture patches) in the 2d example, and to repeatedly paste them onto the surface until it is completely covered. we call such a collection of overlapping patches a lapped texture. it is rendered using compositing operations, either into a traditional global texture map during a preprocess, or directly with the surface at runtime. the runtime compositing approach avoids resampling artifacts and drastically reduces texture memory requirements.  through a simple interface, the user specifies a tangential vector field over the surface, providing local control over the texture scale, and for anisotropic textures, the orientation. to paste a texture patch onto the surface, a surface patch is grown and parametrized over texture space. specifically, we optimize the parametrization of each surface patch such that the tangential vector field aligns everywhere with the standard frame of the texture patch. we show that this optimization is solved efficiently as a sparse linear system.  emil praun adam finkelstein hugues hoppe
interactive exploration of volume line integral convolution based on 3d-texture mapping  line integral convolution (lic) is an effective technique for visualizing vector fields. the application of lic to 3d flow fields has yet been limited by difficulties to efficiently display and animate the resulting 3d-images. texture-based volume rendering allows interactive visualization and manipulation of 3d-lic textures. in order to ensure the comprehensive and convenient exploration of flow fields, we suggest interactive functionality including transfer functions and different clipping mechanisms. thereby, we efficiently substitute the calculation of lic based on sparse noise textures and show the convenient visual access of interior structures. further on, we introduce two approaches for animating static 3d-flow fields without the computational expense and the immense memory requirements for pre-computed 3d-textures and without loss of interactivity. this is achieved by using a single 3d-lic texture and a set of time surfaces as clipping geometries. in our first approach we use the clipping geometry to pre-compute a special 3d-lic texture that can be animated by time-dependent color tables. our second approach uses time volumes to actually clip the 3d-lic volume interactively during rasterization. additionally, several examples demonstrate the value of our strategy in practice.  c. rezk- salama p. hastreiter c. teitzel t. ertl
the implementation of an algorithm in macsyma: computing the formal solutions of differential systems in the neighborhood of regular singular point  we discuss in this paper the problems arised in the implementation in macsyma of a direct algorithm for computing the formal solutions of differential systems in the neighborhood of regular singular point.  the differential system to be considered is of the form xh dy/dx = a(x) y (1) with a(x) = a0 \\+ a1 \\+ … is an n by n matrices of formal series.  this paper deals with system of the form (1) with h = 1. another paper [3] has considered the systems with h > 1\\. so these two papers give complete consideration of systems in the form (1) in a neighborhood of both regular and irregular singular point without reducing the systems to super-irreducible forms, i.e. without knowing (for h > 1) a singular point is regular or irregular.  the first step in the algorithm is to transform the leading matrix a0 to its jordan form, for which we can use the algorithm in [1][11] that computes at first the frobenius form and then reduces it to its jordan form. the reduction from the frobenius matrix to its jordan matrix is based on a theorem in wilkinson [13] which reduces each companion matrix to its jordan matrix. one of the important aspects is that we don't compute the eigenvalues of the matrix but just keep them as the roots of some corresponding polynomials, i.e. they are looked as algebraic numbers.  one simple case in the computations is that when the eigenvalues of the leading matrix a0 have no integer differences, which is called the generic case.  the formal solutions of the differential system can be obtained by solving a linear system of the form a x \- x b = c with a and b in jordan form. the implementation of this resolution is immediate. hence this gives the fundamental system of formal solutions wanted.  for the general case, we should determine at first the integer differences of the eigenvalues of the matrix a0. a classical method is applied and implemented in macsyma for our situation. then we search for some transformations to reduce the differential system to the generic case.  then an interesting question arised: how to compute the jordan normal form of the new leading matrix whose entries are rational functions of the eigenvalues which are algebraic numbers. we have studied these problems and proposed two algorithms for two different cases. these algorithms are implemented in macsyma.  g. chen i. gil
a comment on "a fast parallel algorithm for thinning digital patterns"  a fast parallel thinning algorithm for digital patterns is presented. this algorithm is an improved version of the algorithms introduced by zhang and suen [5] and stefanelli and rosenfeld [3]. an experiment using an apple ii and an epson printer was conducted. the results show that the improved algorithm overcomes some of the disadvantages found in [5] by preserving necessary and essential structures for certain patterns which should not be deleted and maintains very fast speed, from about 1.5 to 2.3 times faster than the four- step and two-step methods described in [3] although the resulting skeletons look basically the same.  h. e. lu p. s. p. wang
on the design and evaluation of a multi-dimensional approach to information retrieval (poster session)  _we present a method of searching text collections that takes advantage of hierarchrical information within documents and integrates searches of structured and unstructured data. we show that multidimensional databases (mdb), designed for accessing data along hierarchical dimensions, are effective for information retrieval. we demonstrate a method of using on-line analytic processing (olap) techniques on a text collection. this combines traditional information retrieval and the slicing, dicing, drill-down, and roll-up of olap. we demonstrate use of a prototype for searching documents from the trec collection._  m. catherine mccabe jinho lee abdur chowdhury david grossman ophir frieder
digital design of a surgical simulator for interventional mr imaging (case study)  we present the design of a simulator for a prototype interventional magnetic resonance imaging scanner. this mri scanner is integrated with an operating theater, enabling new techniques in minimally invasive surgery. the simulator is designed with a threefold purpose: (1) to provide a rehearsal apparatus for practicing and modifying conventional procedures for use in the magnetic environment, (2) to serve as a visualization workstation for procedure planning and previewing as well as a post-operative review, and (3) to form the foundation of a laboratory workbench for the development of new surgical tools and procedures for minimally invasive surgery. the simulator incorporates preoperative data, either mri or ct exams, as well as data from commercial surgical planning systems. dynamic control of the simulation and interactive display of preoperative data in lieu of intra-operative data is handled via an opto- electronic tracking system. the resulting system is contributing insights into how best to perform visualization for this new surgical environment.  terry s. yoo penny rheingans
rule-based versus structure-based models for explaining and generating expert behavior  flexible representations are required in order to understand and generate expert behavior. although production rules with quantifiers can encode experiential knowledge, they often have assumptions implicit in them, making them brittle in problem scenarios where these assumptions do not hold. qualitative models achieve flexibility by representing the domain entities and their interrelationships explicitly. however, in problem domains where assumptions underlying such models change periodically, it is necessary to be able to synthesize and maintain qualitative models in response to the changing assumptions. in this paper we argue for a representation that contains partial model components that are synthesized into qualitative models containing entities and relationships relevant to the domain. the model components can be replaced and rearranged in response to changes in the task environment. we have found this "model constructor" to be useful in synthesizing models that explain and generate expert behavior, and have explored its ability to support decision making in the problem domain of business resource planning, where reasoning is based on models that evolve in response to changing external conditions or internal policies.  vasant dhar harry e. pople
reflectance and texture of real-world surfaces  in this work, we investigate the visual appearance of real-world surfaces and the dependence of appearance on the geometry of imaging conditions. we discuss a new texture representation called the btf (bidirectional texture function) which captures the variation in texture with illumination and viewing direction. we present a btf database with image textures from over 60 different samples, each observed with over 200 different combinations of viewing and illumination directions. we describe the methods involved in collecting the database as well as the importqance and uniqueness of this database for computer graphics. a related quantity to the btf is the familiar brdf (bidirectional reflectance distribution function). the measurement methods involved in the btf database are conducive to simultaneous measurement of the brdf. accordingly, we also present a brdf database with reflectance measurements for over 60 different samples, each observed with over 200 different combinations of viewing and illumination directions. both of these unique databases are publicly available and have important implications for computer graphics.  kristin j. dana bram van ginneken shree k. nayar jan j. koenderink
remindings and their effects in learning a text editor  how can learning in text-editing be characterized? much recent work has focused on the use of analogies from prior experience. in this paper, we investigate the retrievals of earlier experiences within the editor and how they might be used by analogy to accomplish the task and learn the editor. an experiment is presented that demonstrates the effects of these "remindings" on performance. in addition, some possible determinants of these remindings are investigated. this experiment points out the need to consider not only the general form of instruction, but also the specifics of the instructional sequence as well. irrelevant aspects of the task may have strong effects on performance. we consider three teaching techniques, designed to take advantage of these effects in different ways.  brian h. ross thomas p. moran
new techniques for ray tracing procedurally defined objects  we present new algorithms for efficient ray tracing of three procedurally defined objects: fractal surfaces, prisms, and surfaces of revolution. the fractal surface algorithm performs recursive subdivision adaptively. subsurfaces which cannot intersect a given ray are culled from further consideration. the prism algorithm transforms the three dimensional ray- surface intersection problem into a two dimensional ray-curve intersection problem, which is solved by the method of strip trees. the surface of revolution algorithm transforms the three dimensional ray-surface intersection problem into a two dimensional curve-curve intersection problem, which again is solved by strip trees.  james t. kajiya
autonomous mobile manipulators managing perception and failures  we present a control system for autonomous mobile manipulators based on a theory of actions integrated with a theory of perception and failures. the system applies to autonomous manipulators built for simple missions like building towers of blocks, collecting balls of paper and putting them into a bin, or clearing obstacles from a path. for these application domains we have built three autonomous agents: armhand0, armhandone and a.r.r.i.g.o. the core of the system is a high level program controlling the on-line agent behaviour: while a goal is not achieved, it selects a task from a library of possible subplans and executes it. the task, when correctly chosen, must lead to a subgoal position. at the end of each task execution, visual perception is used to monitor the coherence between the configuration of the domain and the configuration entailed as a consequence of the execution of the task. in case of a misalignment between the predicted state and the perceived one, a diagnostic procedure is activated.  alberto finzi fiora pirri marco pirrone massimo romano milko vaccaro
zippered polygon meshes from range images  range imaging offers an inexpensive and accurate means for digitizing the shape of three-dimensional objects. because most objects self occlude, no single range image suffices to describe the entire object. we present a method for combining a collection of range images into a single polygonal mesh that completely describes an object to the extent that it is visible from the outside.  the steps in our method are: 1) align the meshes with each other using a modified iterated closest-point algorithm, 2) zipper together adjacent meshes to form a continuous surface that correctly captures the topology of the object, and 3) compute local weighted averages of surface positions on all meshes to form a consensus surface geometry.  our system differs from previous approaches in that it is incremental; scans are acquired and combined one at a time. this approach allows us to acquire and combine large numbers of scans with minimal storage overhead. our largest models contain up to 360,000 triangles. all the steps needed to digitize an object that requires up to 10 range scans can be performed using our system with five minutes of user interaction and a few hours of compute time. we show two models created using our method with range data from a commercial rangefinder that employs laser stripe technology.  greg turk marc levoy
plenoptic stitching: a scalable method for reconstructing 3d interactive walk throughs  interactive walkthrough applications require detailed 3d models to give users a sense of immersion in an environment. traditionally these models are built using computer-aided design tools to define geometry and material properties. but creating detailed models is time-consuming and it is also difficult to reproduce all geometric and photometric subtleties of real-world scenes. computer vision attempts to alleviate this problem by extracting geometry and photogrammetry from images of the real-world scenes. however, these models are still limited in the amount of detail they recover.  image-based rendering generates novel views by resampling a set of images of the environment without relying upon an explicit geometric model. current such techniques limit the size and shape of the environment, and they do not lend themselves to walkthrough applications. in this paper, we define a parameterization of the 4d plenoptic function that is particularly suitable for interactive walkthroughs and define a method for its sampling and reconstructing. our main contributions are: 1) a parameterization of the 4d plenoptic function that supports walkthrough applications in large, arbitrarily shaped environments; 2) a simple and fast capture process for complex environments; and 3) an automatic algorithm for reconstruction of the plenoptic function.  daniel g. aliaga ingrid carlbom
a demonstration of a legal reasoning system based on teleological analogies  in this article, we demonstrate our analogical legal reasoning system based on a teleological approach to interpret laws, using an actual example. by this demonstration, we show the validity of our approach. the example is based on a real legal problem and consists of an actual case, the actual decision on the case by the japanese supreme court and two major doctrines on the case in japan. the problem and the doctrines are also analyzed from the viewpoint of gda (goal-dependent abstraction) framework in this article. we further show that our system using gda can provide helpful information to evaluate and revise interpretations of legal rules.  tokuyasu kakuta makoto haraguchi
a knowledge-based electronic information and documentation system  we describe the capabilities of a knowledge-based system to automatically generate a collection of electronic notebooks containing various forms of online documentation and reports. this system is a subsystem of a larger knowledge-based system called scinapse. scinapse's raison d'etre is to transform high-level simulation problem specifications into executable numerical programs. the electronic notebooks are generated from the same domain knowledge bases that the system uses to perform its primary tasks. these online notebooks are of two different kinds: reference materials and reports. reference materials are generated from the latest version of the knowledge base, which includes the classes that drive the system, and a network of objects representing meta-information about the system. the reference materials document the system's capabilities and help users understand what the system can do. reports are generated from the instances created by a run of the system. they document the transformations the input specification underwent in becoming code, and are intended to help a user understand what the system has done.  we have found that our approach to producing documents has both advantages and disadvantages when compared with more traditional approaches to documentation. the advantages are that we can minimize the manual effort that is involved in writing documentation about the system, while at the same time maximizing the accuracy of the documentation that is produced.  the main disadvantage has been the lack of truly appropriate authoring tools built to work in our environment. when we began, we expected the task of creating such authoring tools to be much easier than it has turned out to be. later in this paper, we explore some of the factors that have caused this to be the case.  robert l. young elaine kant larry a. akers
"&amp;dbarbelow;&amp;ebarbelow;termining operational policies for oil flow and tanker loading through simulation"  in this paper the use of simulation in addressing the specific needs of one oil company's tanker scheduling problem is examined. the situation is actually more involved than simply tanker scheduling. the flow of oil from the wells to the storage facility must also be considered. this flow is constrained by governmental regulations and profit considerations. a network-discrete event- continuous simulation model, written in slam, was developed to address certain issues of interest to the oil company. these were issues such as a desirable mean time between tanker arrivals and the adequacy of the current storage facility. the latter was also of interest to the government involved, since there were usually tankers waiting to be loaded. the results show that tanker arrival schedule can be developed and that the current storage facility is adequate to meet this company's needs.  c. p. koelling w. h. remy
subproblem finder and instance checker, two cooperating modules for theorem provers  properties are proved about instance, a theorem prover module that recognizes that a formula is a special case and/or an alphabetic variant of another formula, and about insurer, another theorem prover module that decomposes a problem, represented by a formula, into independent subproblems, using a conjunction. the main result of instance is soundness; the main result of insurer is a maximum decomposition into subproblems (with some provisos). experimental results show that a connection graph theorem prover extended with these modules is more effective than the resolution-based connection graph theorem prover alone.  dennis de champeaux
shape from projected light grid (abstract only)  an algorithm is proposed to obtain local surface orientation from the distortion of the projected light stripes in the image of the surface. only partial camera calibration is required for the computations of surface normals. only the directions of the optical axis and the projector axis are required from the 3-d scene for this algorithm. a mapping is defined from points in the image to points on the gaussian sphere associated with the object. this mapping is based on the measurements of the distorted "quadrilaterals" in the image. experimental results are obtained both for planar and curved surfaces.  there are many "shape from" methods discussed in the literature. surface normals can be obtained by calculating the spatial variation of brightness (shape from shading [4] ); by noting the distortion of texture elements (shape from texture [1]); by using range data directly (shape from stereo [3]); or by using the image of a moving object (shape from motion [2]). our approach is similar to shape from texture, but we use externally imposed light stripes to simulate texture. thus we can guarantee "texture" elements of known uniform sizes.  we project a grid of light stripes on the scene. knowledge of optical axis and projector axis is assumed. we further make the assumption of parallel projection. the light grids are observed as distorted quadrilaterals in the image. the amount of distortion is a function of the normal to the surface on which the grid is being projected. lengths of the sides of these quadrilaterals measured in the image are then used to calculate the local surface normal. the algorithm can be used both on planar and curved surfaces.  neelima shrikhande
feynmann diagrams and spreading illusions "schwinger's quantum electrodynamics and feynmann's may have been mathematically the same, but one was conservative and the other revolutionary. one extended an existing line of thought. the other broke with the past decisively enough to mystify its intended audience. one represented an ending: a mathematical style doomed to be fatally overcomplex. the other, for those willing to follow feynmann into a new style of visualization, served as a beginning. feynmann's style was risky, even megalomaniacal." [1] thomas g. west
integrating shape and pattern in mammalian models  the giraffe and its patches, the leopard and its spots, the tiger and its stripes are spectacular examples of the integration of a pattern and a body shape. we present an approach that integrates a biologically-plausible pattern generation model, which can effectively deliver a variety of patterns characteristic of mammalian coats, and a body growth and animation system that uses experimental growth data to produce individual bodies and their associated patterns automatically. we use the example of the giraffe to illustrate how our approach takes us from a canonical embryo to a full adult giraffe in a continuous way, with results that are not only realistic looking, but also objectively validated. the flexibility of the approach is demonstrated by examples of big cat patterns, including an interpolation between patterns. the approach also allows a considerable amount of user control to fine-tune the results and to animate the resulting body with the pattern.  marcelo walter alain fournier daniel menevaux