bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling 3D Curves of Minimal Energy
Authors: Veltkamp Remco C. , Wesselink Wieger 
Published: September 2009

AbstractModeling a curve through minimizing its energy yields an overall smooth curve. A common way to model shape features is to perform the minimization subject to a number of interpolation constraints. This way of modeling is attractive because the designer is not bothered with the precise representation of the curve (e.g. control points). However, local shape specification by means of interpolation constraints is very limited. On the other hand, local deformation by repositioning control points is powerful but very laborious, and destroys the minimal energy property. In this paper, deform operators are introduced for 3D curve modeling that have built‐in energy terms that have an intuitive effect. These operators allow local shape modification and do justice to the energy minimization way of modeling.
Thoughtful Drawings: A Computational Model of the Cognitive Nature of Children's Drawing
Authors: Burton Ed 
Published: September 2009

AbstractAn interpretation of children's drawing is presented that is based on active perception of the world and the construction of an equivalent self contained two‐dimensional world. This model is implemented in a computer program called Rose (Representation Of Spatial Experience). Inspired by the drawings of young children, Rose simulates the perception of the general form and structure of three‐dimensional computer models and constructs equivalent childlike two‐dimensional representations from them. Rose serves to illustrate the plausibility of the constructive process as a model for real children's drawing and in addition serves as an alternative approach to traditional computer graphic rendering.
Visibility and Dead‐Zones in Digital Terrain Maps
Authors: Or Daniel Cohen , Shaked Amit 
Published: September 2009

AbstractThe problem of detecting the visible and hidden areas of a topographic surface from a given viewpoint is well known, and has applications in GIS and other fields. The computational geometry literature is rich with solutions based on a polygonal representation of the surface. This work confronts the problem by working directly on the Digital Elevation Map which represents the terrain surface. We present an algorithm that processes discrete lines of sight from the viewpoint to the surface perimeter, and tests the unit‐sized terrain elements along the discrete cross‐sections defined by these lines. The algorithm is very efficient, performing O(n) testing operations, consisting of a few additions and no more than one multiplication each, where n is the number of the terrain elements in the map.
Morphological Operations for Color‐Coded Images
Authors: Busch Christoph , Eberle Michael 
Published: September 2009

AbstractThe subject of this paper is the semantically based postprocessing of color–coded images such as classification results. We outline why the classical definition of mathematical morphology suffers if it is used for processing of coded image data. Therefore we provide an extension for morphological operations such as dilation, erosion, opening, and closing. With a new understanding of morphology we introduce bridging and tunneling as further combinations of dilation and erosion. The extensions are applied to medical image data, where the semantic rules stem from basic anatomical knowledge.
Fast Shadowing Algorithm for Linear Light Sources
Authors: Tanaka Toshimitsu , Takahashi Tokiichiro 
Published: September 2009

AbstractThis paper presents a fast shadowing algorithm for linear light sources that uses a ray‐oriented buffer. Space segmentation by the buffer guarantees that if a point is included in a subspace, all light rays toward the point are also contained in the subspace. Each cell of the buffer stores a list of objects that lie within or intersect the subspace allocated to the cell. Therefore, candidate objects, those that may cast shadows onto a point, are determined by referring to the cell where the point is mapped. In addition, whether each candidate object actually casts shadows or not is tested with the bounding‐volume of the shadow space to reduce the number of objects subjected to expensive light clipping. The bounding‐volumes are also stored in the buffer. For efficiently generating the ray‐oriented buffer, we present the cylindrical scan‐conversion algorithm. The algorithm preconverts objects' surfaces to trapezia to decrease the light clipping cost, then connects the trapezia to the buffer cells.Due to the above improvements, our algorithm achieves over 10 times faster shadow generation compared to the conventional methods. Experimental results confirm that our method can generate realistic images with soft shadows in a few minutes.
A Quick Rendering Method Using Basis Functions for Interactive Lighting Design
Authors: Dobashi Yoshinori , Kaneda Kazufumi , Nakatani Hideki , Yamashita Hideo , Nishita Tomoyuki 
Published: September 2009

AbstractWhen designing interior lighting effects, it is desirable to compare a variety of lighting designs involving different lighting devices and directions of light. It is, however, time‐consuming to generate images with many different lighting parameters, taking interreflection into account, because all luminances must be calculated and recalculated. This makes it difficult to design lighting effects interactively. To address this problem, this paper proposes a method of quickly generating images of a given scene illustrating an interreflective environment illuminated by sources with arbitrary luminous intensity distributions. In the proposed method, the luminous intensity ditribution is expressed with basis functions. The proposed method uses a series of spherical harmonic functions as basis functions, and calculates in advance each intensity on surfaces lit by the light sources whose luminous intensity distribution are the same as the spherical harmonic functions. The proposed method makes it possible to generate images so quickly that we can change the luminous intensity distribution interactively. Combining the proposed method with an interactive walk‐through that employs intensity mapping, an interactive system for lighting design is implemented. The usefulness of the proposed method is demonstrated by its application to interactive lighting design, where many images are generated by altering lighting devices and/or direction of light.
Sketching 3D Animations
Authors: Balaguer Jean‐Francis , Gobbetti Enrico 
Published: September 2009

AbstractWe are interested in providing animators with a general‐purpose tool allowing them to create animations using straight‐ahead actions as well as pose‐to‐pose techniques. Our approach seeks to bring the expressiveness of real‐time motion capture systems into a general‐purpose multi‐track system running on a graphics workstation. We emphasize the use of high‐bandwidth interaction with 3D objects together with specific data reduction techniques for the automatic construction of editable representations of interactively sketched continuous parameter evolution. In this paper, we concentrate on providing a solution to the problem of applying data reduction techniques in an animation context. The requirements that must be fulfilled by the data reduction algorithm are analyzed. From the Lyche and Mørken knot removal strategy, we derive an incremental algorithm that computes a B‐spline approximation to the original curve by considering only a small piece of the total curve at any time. This algorithm allows the processing of the user's captured motion in parallel with its specification, and guarantees constant latency time and memory needs for input motions composed of any number of samples. After showing the results obtained by applying our incremental algorithm to 3D animation paths, we describe an integrated environment to visually construct 3D animations, where all interaction is done directly in three dimensions. By recording the effects of user's manipulations and taking into account the temporal aspect of the interaction, straight‐ahead animations can be defined. Our algorithm is automatically applied to continuous parameter evolution in order to obtain editable representations. The paper concludes with a presentation offuture work.
An Adaptive Spatial Subdivision of the Object Space for Fast Collision Detection of Animated Rigid Bodies
Authors: Bandi Srikanth , Thalmann Daniel 
Published: September 2009

AbstractCollision detection tests between objects dominate run time simulation of rigid body animation. Traditionally, hierarchical bounding box tests are used to minimize collision detection time. But the bounding boxes do not take shapes of the objects into account which results in a large number of collision detection tests. We propose an adaptive spatial subdivision of the object space based on octree structure to rectify this problem. We also present a technique for efficiently updating this structure periodically during the simulation.
Multiresolution B‐spline Radiosity
Authors: Yu Yizhou , Peng Qunsheng 
Published: September 2009

AbstractThis paper introduces a kind of new wavelet radiosity method called multiresolution B‐spline radiosity, which uses B‐splines of different scales to represent radiosity distribution functions. A set of techniques and algorithms, such as function extrapolation, adaptive quadrature, scale adjustment and octree, are proposed to implement it. This method sets up hierarchical structures on surfaces, keeps radiosity distribution continuous at element boundaries, does not need postprocessing, and does not prevent the use of any surface whose parameter domain is rectilinear.
VR‐VIBE: A Virtual Environment for Co‐operative Information Retrieval
Authors: Benford Steve , Snowdon Dave , Greenhalgh Chris , Ingram Rob , Knox Ian , Brown Chris 
Published: September 2009

AbstractWe present a virtual reality application called VR‐VIBE which is intended to support the co‐operative browsing and filtering of large document stores. VR‐VIBE extends a visualisation approach proposed in a previous two dimensional system called VIBE into three dimensions, allowing more information to be visualised at one time and supporting more powerful styles of interaction, The essence of VR‐VIBE is that multiple users can explore the results of applying several simultaneous queries to a corpus of documents. By arranging the queries into a spatial framework, the system shows the relative attraction of each document to each query by its spatial position and also shows the absolute relevance of each document to all of the queries. Users may then navigate the space, select individual documents, control the display according to a dynamic relevance threshold and dynamically drag the queries to new positions to see the effect on the document space. Co‐operative browsing is supported by directly embodying users and providing them with the ability to interact over live audio connections and to attach brief textual annotations to individual documents. Finally, we conclude with some initial observations gleaned from our experience of constructing VR‐VIBE and using it in the laboratory setting.
Realizing 3D Visual Programming Environments within a Virtual Environment
Authors: Van Reeth F. , Coninx K. , De Backer S. , Flerackers E. 
Published: September 2009

AbstractIn the visual programming community, many interesting graphical metaphors have been reported upon for representing computer programs graphically. Most of them have a 2D or 2.5D appearance on the screen in order to reflect the inherent multi‐dimensionality of the programming constructs being represented. By going into a three‐dimensional representation, this reflection can go a stepfurther. With ever increasing3D graphics rendering capabilities on todays computers, it moreover becomes feasible to extend the dimensionality of the program (and data structure) depiction. We follow this approach by realizing 3D graphical programming techniques within CAEL, our interactive Computer Animation Environment Language. The paper elucidates how several concepts, traditionally found within the Virtual Environments area, can be utilized in the realization of three‐dimensional Programming Environments.
Filtering, Clustering and Hierarchy Construction: a New Solution for Ray‐Tracing Complex Scenes
Authors: Cazals Frédéric , Drettakis George , Puech Claude 
Published: September 2009

AbstractData structures that handle very complex scenes (hundreds of thousands of objects) have in the past either been laboriously built by hand, or have required the determination of unintuitive parameter values by the user. It is often the case that an incorrect choice of these parameters can result in greedy memory requirements or severely degraded performance. As a remedy to this problem we propose a new data structure which is fully automatic since it does not require the user to determine any input parameters. The structure is built by first filtering the input objects by size, subsequently applying a clustering step to objects of the same size and finally building a hierarchy of uniform grids . We then show that this data structure can be efficiently constructed. The implementation of the

shows that the new structure is stable since it's memory requirements grow linearly with the size of the scene, and that it presents a satisfactory compromise between memory usage and computational efficiency. A detailed comparison with previous data structures is also presented in the results.
Generating a Texture Map from Object‐Surface Texture Data
Authors: Maruya Makoto 
Published: September 2009

AbstractA number of 3D digitizing methods, including stereopsis, are capable of measuring not only an object's shape but also its surface texture. Measured shape data can be expressed as a polyhedron whose faces are triangular, and object‐surface texture data can be represented in the form of color data for each of the vertices of the various triangles. The ability to apply object‐surface texture data directly to the creation of computer graphics images has been severely limited by the extreme difficulty of expressing such texture data in the image from which conventional texture mapping proceeds (commonly referred to as a texture map). Proposed here is a method that generates a texture map from object‐surface texture data. First, the method reduces the number of triangles in the polyhedron while preserving essentially all the color data that it originally contained. Next, it arranges the triangles in the simplified triangle mesh onto a plane, and generates a texture map from this arrangement. This method preserves the full texture of an object, no matter how complex its shape, an advantage over the conventional cylindrical texture representation approach. Furthermore, since essentially all color data has been retained, the reduction in the number of triangles does not produce any significant reduction in the texture‐realism of the object image produced.
Rendering of Surface and Volume Details in Volume Data*
Authors: CAI Wenli , CHEN Tianzhou , SHI Jiaoying 
Published: September 2009

Abstract:Aiming at the detail rendering in volume data, a new volume illumination model, called Composed Scattering Model (CSM), is presented. In order to enhance different details in volume data, scattering intensity is decomposed into volume scattering intensity and surface scattering intensity with different weight functions. According to the Gauss probability distribution of gray and gradient of data, we propose an accurate method to detect the materials in a voxel, called composed segmentation. In addition, we discuss the principle of constructing these weight functions based on the operators defined in composed segmentation. CSM can generate images containing more details than most popular volume rendering models. This model has been applied to the direct volume rendering of 3D data sets obtained by CT and MRI. The resultant images show not only rich details but also clear boundary surfaces. CSM is demonstrated as an accurate volume rendering model suited for detail enhancement in volume data sets.
Fast Wavelet Based Volume Rendering by Accumulation of Transparent Texture Maps
Authors: Lippert L. , Gross M. H. 
Published: September 2009

AbstractIn the following paper, a new method for fast and accurate volume intensity and color integration is elaborated, which employs wavelet decompositions and texture mapping. At this point, it comprises and unifies the advantages of recently introduced Fourier domain volume rendering techniques and wavelet based volume rendering. Specifically, the method computes analytic solutions of the ray intensity integral through a single wavelet by slicing its Fourier transform and by backprojecting it into the spatial domain. The resulting slices can be considered as RGB textures where R, G and B account for the decomposed volume color function. Due to the similarity of the basis functions, the computation of the texture map has to be figured out only once for each 3D mother wavelet. Hence, the final volume rendering procedure turns out to be a superposition of self–similar, transparent and colored textures, which is supported by modern hardware accumulation buffers. Linear shading and attenuation can be introduced by modifications of the wavelet's Fourier transform.The main advantages of this method are the provision of accurate solutions and quantification of error bounds, the absence of any expensive prefiltering and the independence of the computational costs from the image resolution. Furthermore, any required discretization, such as the resolution of the basis textures is defined within the computational framework of the wavelet transform. The method is not restricted to a specific type of wavelet unless is provides an analytic Fourier description, such as any B–spline wavelets do.
Optimal Investment Decisions for Two Positioned Firms Competing in a Duopoly Market with Hidden Competitors
Authors: Armada Manuel Rocha , Kryzanowski Lawrence , Pereira Paulo Jorge 
Published: September 2009

Abstract This paper extends the literature dealing with the option to invest in a duopoly market for a leader‐follower setting. A restrictive assumption embodied in the models in the current literature is that investment opportunities are semi‐proprietary in that the two identified or positioned firms are guaranteed to hold at least the follower's position. More competition is realistically captured in our model by introducing the concept of hidden rivals so that the places in the market can be taken not only by positioned firm but also by these hidden competitors. The value functions and the optimal triggers for the positioned firms differ materially in settings with(out) the presence of hidden rivals. Unlike existing models, our model allows for (a)symmetric market shares and investment costs for the leader and the follower. Cooperative entrance by the two positioned firms is also modelled.
MDG 5: how close are we to success?
Authors: Islam M , Yoshida S 
Published: September 2009

Only 6 years are left until 2015, the target date for achieving the Millennium Development Goals (MDG), yet improving maternal health (MDG 5) continues to lag behind. At the global level, maternal mortality still remains high in sub‐Saharan Africa and Southeast Asian countries. Most deaths are preventable and occur due to unavailability of and/or poor quality of service.Skilled care at facilities ensures safety, cleanliness, the availability of supplies and equipment, and it makes management and supervision easier. With the mixture of professionals in a facility, life‐saving emergency care can be provided quickly. Wherever childbirth takes place, it is essential that the person who helps has the core competencies for safe delivery, has the necessary equipment and supplies, and has the option to refer to a functioning facility offering emergency obstetric and newborn care.The continuing high incidence of maternal and perinatal mortality and morbidity is unacceptable precisely because it is solvable. We know how to make pregnancy and childbirth safe. The task is enormous but not insurmountable. Our efforts of investment need to be equal to the tasks and must be intensified if maternal and perinatal morbidity and mortality is to be reduced.
Evaluation of various gentamicin dosage regimens in geriatric patients: a simulation study
Authors: Bourguignon Laurent , Goutelle Sylvain , De Saint‐Martin Julie Burdin , Maire Pascal , Ducher Michel 
Published: September 2009

AbstractThe aim of this simulation study was to evaluate the ability of three regimens proposed in official French recommendations for gentamicin to hit defined pharmacokinetic (PK) and pharmacodynamic targets in a population of elderly patients. The first drug regimen tested consisted of a loading dose of 1 mg/kg and a maintenance dose weighted by creatininemia, every 8 h. The second regimen consisted of a fixed dose of 1 mg/kg at various intervals of time, calculated from creatinine clearance. The last regimen was a fixed dose of 3 mg/kg once a day. All regimens were for 5 days. We used a bicompartmental PK model and implemented a Monte Carlo simulation to generate a large sample of geriatric subjects. The analysis examined three ranges of creatinine clearance. Simulations showed that for the two regimens using multiple doses per day, neither was able to reach an efficacy level without significant toxicity after 5 days of treatment, regardless of the level of renal function. The use of creatininemia or creatinine clearance to adjust the drug dose did not alter these findings. The once‐a‐day dosing regimen gave better results both in efficacy and toxicity, except for patients with creatinine clearance lower than 60 mL/min, where the incidence of potential toxicity was above 25%. These results strongly suggest that official French recommendations about aminoglycoside dosage regimens in elderly patients with renal impairment should be updated, and that the frequent need for therapeutic drug monitoring and dosage individualization should be clearly stated.
Thermocalc and experimental modelling of melting of pelite, Morton Pass, Wyoming
Authors: GRANT J. A. 
Published: September 2009

AbstractCalculated results using thermocalc for melting of pelitic compositions are compared with the results of experimental melting of pelite from Morton Pass, Wyoming, USA. The experiments were carried out at 1, 2 and 3.5 kbar, dominantly at 2 kbar. For experimental charges with (‘wet’) and without (‘dry’) added H2O, the agreement is good. This is true for the compositions without added H2O, in which liquid first appears with the production of orthopyroxene at ∼800 °C, and for the runs with added H2O, in which melting begins at ∼700 °C, and continues, with the appearance of orthopyroxene between 780 and 800 °C at 2 kbar. The compositions of melts are also compared: the comparison is generally good, except in the modelling of wet runs below ∼780 °C, where the calculated values for FeO and MgO are about one‐tenth of the already low analytical values, and in somewhat low calculated values of Al2O3 compared to the analytical data. A quantitative model to illustrate melting of pelite at Morton Pass is calculated, giving T–X(H2O) conditions for the observed sets of natural assemblages, along with the reactions at and near the beginning of melting.