bluuebunny/crossref_metadata_2025 huggingface dataset:
TheTIME FOR COFFEEGene Maintains the Amplitude and Timing of Arabidopsis Circadian Clocks[W]
Authors: Hall Anthony , Bastow Ruth M. , Davis Seth J. , Hanano Shigeru , McWatters Harriet G. , Hibberd Victoria , Doyle Mark R. , Sung Sibum , Halliday Karen J. , Amasino Richard M. , Millar Andrew J.
Published: November 2003

Plants synchronize developmental and metabolic processes with the earth's 24-h rotation through the integration of circadian rhythms and responses to light. We characterize the time for coffee (tic) mutant that disrupts circadian gating, photoperiodism, and multiple circadian rhythms, with differential effects among rhythms. TIC is distinct in physiological functions and genetic map position from other rhythm mutants and their homologous loci. Detailed rhythm analysis shows that the chlorophyll a/b-binding protein gene expression rhythm requires TIC function in the mid to late subjective night, when human activity may require coffee, in contrast to the function of EARLY-FLOWERING3 (ELF3) in the late day to early night. tic mutants misexpress genes that are thought to be critical for circadian timing, consistent with our functional analysis. Thus, we identify TIC as a regulator of the clock gene circuit. In contrast to tic and elf3 single mutants, tic elf3 double mutants are completely arrhythmic. Even the robust circadian clock of plants cannot function with defects at two different phases.
Phospholipase D Activation Correlates with Microtubule Reorganization in Living Plant Cells[W]
Authors: Dhonukshe Pankaj , Laxalt Ana M. , Goedhart Joachim , Gadella Theodorus W. J. , Munnik Teun
Published: November 2003

A phospholipase D (PLD) was shown recently to decorate microtubules in plant cells. Therefore, we used tobacco BY-2 cells expressing the microtubule reporter GFP-MAP4 to test whether PLD activation affects the organization of plant microtubules. Within 30 min of adding n-butanol, a potent activator of PLD, cortical microtubules were released from the plasma membrane and partially depolymerized, as visualized with four-dimensional confocal imaging. The isomers sec- and tert-butanol, which did not activate PLD, did not affect microtubule organization. The effect of treatment on PLD activation was monitored by the in vivo formation of phosphatidylbutanol, a specific reporter of PLD activity. Tobacco cells also were treated with mastoparan, xylanase, NaCl, and hypoosmotic stress as reported activators of PLD. We confirmed the reports and found that all treatments induced microtubule reorganization and PLD activation within the same time frame. PLD still was activated in microtubule-stabilized (taxol) and microtubule-depolymerized (oryzalin) situations, suggesting that PLD activation triggers microtubular reorganization and not vice versa. Exogenously applied water-soluble synthetic phosphatidic acid did not affect the microtubular cytoskeleton. Cell cycle studies revealed that n-butanol influenced not just interphase cortical microtubules but also those in the preprophase band and phragmoplast, but not those in the spindle structure. Cell growth and division were inhibited in the presence of n-butanol, whereas sec- and tert-butanol had no such effects. Using these novel insights, we propose a model for the mechanism by which PLD activation triggers microtubule reorganization in plant cells.
Differential Subnuclear Localization of RNA Strands of Opposite Polarity Derived from an Autonomously Replicating Viroid[W]
Authors: Qi Yijun , Ding Biao
Published: November 2003

The wide variety of RNAs produced in the nucleus must be localized correctly to perform their functions. However, the mechanism of this localization is poorly understood. We report here the differential subnuclear localization of RNA strands of opposite polarity derived from the replicating Potato spindle tuber viroid (PSTVd). During replication, (+)- and (−)-strand viroid RNAs are produced. We found that in infected cultured cells and plants, the (−)-strand RNA was localized in the nucleoplasm, whereas the (+)-strand RNA was localized in the nucleolus as well as in the nucleoplasm with distinct spatial patterns. Furthermore, the presence of the (+)-PSTVd in the nucleolus caused the redistribution of a small nucleolar RNA. Our results support a model in which (1) the synthesis of the (−)- and (+)-strands of PSTVd RNAs occurs in the nucleoplasm, (2) the (−)-strand RNA is anchored in the nucleoplasm, and (3) the (+)-strand RNA is transported selectively into the nucleolus. Our results imply that the eukaryotic cell has a machinery that recognizes and localizes the opposite strands of an RNA, which may have broad ramifications in the RNA regulation of gene expression and the infection cycle of pathogenic RNAs and in the development of RNA-based methods to control gene expression as well as pathogen infection.
Institutions of Conflict Management and Economic Growth in the European Union
Authors: Schneider Friedrich , Wagner Alexander F.
Published: November 2003

High‐quality institutions of conflict management can serve to mitigate the negative effects of adverse external shocks and social conflict on long‐run economic growth. But in addition to the benefits (production‐enhancing cooperation), there are also costs (taxes and rent‐seeking) of conflict‐management institutions like corporatism and trust. We examine both positive and negative influences in the context of a simple growth model. Contrary to previous research, we predict a non‐linear relationship between institutions and growth. The empirical evidence from a panel for the years 1961‐1995 shows that neo‐corporatism and trust have each had independent positive effects on long‐run growth in the EU, suggesting that the diminishing product range of institutions has not yet been reached. Under an increasing size of government, however, both institutions lead to a dominating negative rent‐seeking effect.

Our thanks for helpful comments go to the editors, an anonymous referee, Karl Aiginger, Mathias Dufour, Frauke Skudelny, Robert Urbatsch, seminar participants at the University of Linz, the Austrian Institute for Economic Research and discussants at the European Public Choice Society Meeting 2000 in Siena. All remaining errors are ours, of course. An extended version of this paper is available from the authors on request (Schneider and Wagner 2001). Further results are discussed in Wagner (2000).
European Monetary Union, the Term Structure, and the Lucas Critique
Authors: Bergeijk Peter A. G. Van , Berk Jan Marc
Published: November 2003

In order to evaluate the empirical relevance of the Lucas Critique, we investigate whether the term structure (the relation of the long interest rate to the short interest rate) showed structural change as the deadline for the euro came closer. Our empirical analysis of the term structures (yield curves) in 12 OECD countries uncovers that econometrically estimated behavioural equations for most EMU countries were stable even in the light of the creation of the euro. This finding would seem to defy the Lucas Critique. However, the significant structural instability found for the euro area's core country, Germany, suggests that the Lucas Critique is relevant in the analysis of the impact of the creation (and future extensions) of EMU.

Preliminary versions of this paper were presented at the ECB workshop on yield curve modelling, Frankfurt (1999) and the Finance Seminar at the University of Zurich (2000). Comments by participants of both workshops and by two anonymous referees are gratefully acknowledged.
Privatization and Equity in Brazil and Russia
Authors: Baer Werner , Bang James T.
Published: November 2003

This paper uses cross–national data from happiness surveys, jointly with data on per capita income and pollution, to examine how self–reported well–being varies with prosperity and environmental conditions. This approach allows us to show that citizens care about prosperity and the environment, and to calculate the trade–off people are willing to make between them. The paper finds that the effect of urban air pollution on subjective well–being shows up as a considerable monetary valuation of improved air quality. For instance, a representative German citizen would need to be given more than 1900$ per year in order to accept the typical urban air pollution level prevailing in Japan. The subjective marginal valuation of air pollution is compared with marginal abatement costs from the literature.
Volumetric Filtering, Modeling and Visualization for Nano‐Medicine
Authors: Bajaj Chandrajit
Published: November 2003

The 3D structures of individual proteins or small complexes, such as most of the Protein Data Bank entries, are still unable to yield the ''full picture'' of a functional biological complex. The study of large macromolecular complexes, such as viruses, ion channels, the ribosome and other macromolecular machines of various types, offer more complete structural and functional description of the nano‐machinery of life.

In addition to x‐ray crystallography. NMR spectroscopy, electron cryomicroscopy (cryoEM) imaging of single particles, and in‐vivo molecular tomographic imaging has become indispensable at revealing the structures of large macromolecular complexes at subnanometer resolutions.

In this talk, I shall describe some of the recent computational advances in filtering, modeling, analysis and visualization, that have propelled structure determination by cryoEM and tomographic imaging, to steadily increasing accuracy.
Freeform Shape Representations for Efficient Geometry Processing
Authors: Kobbelt Leif
Published: November 2003

The most important concepts for the handling and storage of freeform shapes in geometry processing applications are parametric representations and volumetric representations. Both have their specific advantages and drawbacks. While the algebraic complexity of volumetric representations is independent from the shape complexity, the domain of a parametric representation usually has to have the same structure as the surface itself (which sometimes makes it necessary to update the domain when the surface is modified).

On the other hand, the topology of a parametrically defined surface can be controlled explicitly while in a volumetric representation, the surface topology can change accidentally during deformation. A volumetric representation reduces distance queries or inside/outside tests to mere function evaluations but the geodesic neighborhood relation between surface points is difficult to resolve. As a consequence, it seems promising to combine parametric and volumetric representations to effectively exploit both advantages.

In this talk, a number of projects are presented and discussed in which such a combination leads to efficient and numerically stable algorithms for the solution of various geometry processing tasks. Applications include global error control for mesh decimation and smoothing, topology control for level‐set surfaces, and shape modeling with unstructured point clouds.
On Visual Similarity Based 3D Model Retrieval
Authors: Chen Ding‐Yun , Tian Xiao‐Pei , Shen Yu‐Te , Ouhyoung Ming
Published: November 2003

A large number of 3D models are created and available on the Web, since more and more 3D modelling anddigitizing tools are developed for ever increasing applications. The techniques for content‐based 3D model retrievalthen become necessary. In this paper, a visual similarity‐based 3D model retrieval system is proposed.This approach measures the similarity among 3D models by visual similarity, and the main idea is that if two 3Dmodels are similar, they also look similar from all viewing angles. Therefore, one hundred orthogonal projectionsof an object, excluding symmetry, are encoded both by Zernike moments and Fourier descriptors as features forlater retrieval. The visual similarity‐based approach is robust against similarity transformation, noise, model degeneracyetc., and provides 42%, 94% and 25% better performance (precision‐recall evaluation diagram) thanthree other competing approaches: (1) the spherical harmonics approach developed by Funkhouser et al., (2) theMPEG‐7 Shape 3D descriptors, and (3) the MPEG‐7 Multiple View Descriptor. The proposed system is on the Webfor practical trial use (http://3d.csie.ntu.edu.tw), and the database contains more than 10,000 publicly available3D models collected from WWW pages. Furthermore, a user friendly interface is provided to retrieve 3D modelsby drawing 2D shapes. The retrieval is fast enough on a server with Pentium IV 2.4 GHz CPU, and it takes about2 seconds and 0.1 seconds for querying directly by a 3D model and by hand drawn 2D shapes, respectively.

Categories and Subject Descriptors (according to ACM CCS): H.3.1 [Information Storage and Retrieval]: Indexing Methods
Field Functions for Blending Range Controls on Soft Objects
Authors: Hsu P. C. , Lee C.
Published: November 2003

This paper proposes new field functions that have adjustable inner radius and outer radius of influence. Incorporatingthe proposed field functions with soft object modeling, soft blending, Ricci's super‐ellipsoid blends, Perlin'sset operations, and R‐functions, etc. can have blending range controls by adjusting the inner and the outer radiiof influence of given field functions. As a result, the sizes of the resulting blending surfaces on soft objects willnot be restricted by the sizes of the blended primitive soft objects and can be enlarged and shrunk freely withoutdeforming the overall shapes of blended primitive soft objects. In addition, a small soft object can have a largeblending region, and a large one can have a small blending region

Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling ‐ Curve, surface, solid and object representations
Fast Photo‐Realistic Rendering of Trees in Daylight
Authors: Qin Xueying , Nakamae Eihachiro , Tadamura Katsumi , Nagai Yasuo
Published: November 2003

We propose a fast approach for photo‐realistic rendering of trees under various kinds of daylight, which is particularlyuseful for the environmental assessment of landscapes. In our approach the 3D tree models are transformedto a quasi‐3D tree database registering geometrical and shading information of tree surfaces, i.e. their normalvectors, relative depth, and shadowing of direct sunlight and skylight, by using a combination of 2D buffers.Thus the rendering speed of quasi‐3D trees depends on their display sizes only, regardless of the complexity oftheir original 3D tree models. By utilizing a two‐step shadowing algorithm, our proposed method can create highquality forest scenes illuminated by both sunlight and skylight at a low cost. It can generate both umbrae andpenumbrae on a tree cast by other trees and any other objects such as buildings or clouds. Transparency, specularreflection and inter‐reflection of leaves, which influence the delicate shading effects of trees, can also be simulatedwith verisimilitude.

Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three dimensional Graphics and Realism
Sub‐Voxel Topology Control for Level‐Set Surfaces
Authors: Bischoff Stephan , Kobbelt Leif
Published: November 2003

Active contour models are an efficient, accurate, and robust tool for the segmentation of 2D and 3D image data.In particular, geometric deformable models (GDM) that represent an active contour as the level set of an implicitfunction have proven to be very effective. GDMs, however, do not provide any topology control, i.e. contours maymerge or split arbitrarily and hence change the genus of the reconstructed surface. This behavior is inadequate insettings like the segmentation of organic tissue or other objects whose genus is known beforehand. In this paperwe describe a novel method to overcome this limitation while still preserving the favorable properties of the GDMsetup. We achieve this by adding (sparse) topological information to the volume representation at locations whereit is necessary to locally resolve topological ambiguities. Since the sparse topology information is attached to theedges of the voxel grid, we can reconstruct the interfaces where the deformable surface touches itself at sub‐voxelaccuracy. We also demonstrate the efficiency and robustness of our method.
Multi‐scale Feature Extraction on Point‐Sampled Surfaces
Authors: Pauly Mark , Keiser Richard , Gross Markus
Published: November 2003

We present a new technique for extracting line‐type features on point‐sampled geometry. Given an unstructuredpoint cloud as input, our method first applies principal component analysis on local neighborhoods toclassify points according to the likelihood that they belong to a feature. Using hysteresis thresholding, we thencompute a minimum spanning graph as an initial approximation of the feature lines. To smooth out the featureswhile maintaining a close connection to the underlying surface, we use an adaptation of active contour models.Central to our method is a multi‐scale classification operator that allows feature analysis at multiplescales, using the size of the local neighborhoods as a discrete scale parameter. This significantly improves thereliability of the detection phase and makes our method more robust in the presence of noise. To illustrate theusefulness of our method, we have implemented a non‐photorealistic point renderer to visualize point‐sampledsurfaces as line drawings of their extracted feature curves.
ShieldTester: Cell‐to‐Cell Visibility Test for Surface Occluders
Authors: Navazo I. , Rossignac J. , Jou J. , Shariff R.
Published: November 2003

We present a novel Cell‐To‐Cell Visibility (C2CV) algorithm, which given two polyhedra, AandBand a connectedand oriented manifold triangle mesh, S offers a simple, fast and conservative test for detecting when A and B areoccluded from each other by S. Previously disclosed C2CV algorithms either relied on costly occlusion fusion orwere restricted to convex or “apparently convex” occluders, which makes them inappropriate for scenes wherepotential occluders are arbitrary triangulated surfaces, such as the body of a car or a portion of a terrain. Thesimplicity of our C2CV algorithm, named ShieldTester, stems from a new Occlusion Theorem, introduced herewhich permits to establish occlusion by computing the intersection of S with a single ray from a vertex ofAtoa vertex ofB. ShieldTester may be used to establish that pairs of cells in a subdivision of space are hidden fromeach other by a relatively large surface occluder, so that when the viewer is in one cell, the objects in the othercell need not be displayed.

Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Computational Geometryand Object Modeling: Occlussion Culling, Visibility Test, Triangle Meshes
Volumetric cell‐and‐portal generation
Authors: Haumont D. , Debeir O. , Sillion F.
Published: November 2003

We present an algorithm to generate a cell‐and‐portal decomposition of general indoor scenes. The method is an adaptation of the 3D watershed transform, computed on a distance‐to‐geometry sampled field. The watershed is processed using a flooding analogy in the distance field space. Flooding originates from local minima, each minimum producing a region. Portals are built as needed to avoid the merging of regions during their growth. As a result, the cell‐and‐portal decomposition is closely linked to the structure of the models. In a building, the algorithm finds all the rooms, doors and windows. To restrict the memory load, a hierarchical implementation of the algorithm is presented. We also explain how to handle possible model degeneracies ‐such as cracks, holes and interpenetrating geometries‐ using a pre‐voxelisation step. The hierarchical algorithm, preceded when necessary by the pre‐voxelisation, was tested on a large range of models. We show that it is able to deal with classical architectural models, as well as cave‐like environments and large mixed indoor/outdoor scenes. Thanks to the intermediate distance field representation, the algorithm can be used regardless of the way the model is represented: it deals with parametric curves, implicit surfaces, volumetric data and polygon soups in a unified way.
Planning Collision‐Free Reaching Motions for Interactive Object Manipulation and Grasping
Authors: Kallmann Marcelo , Aubel Amaury , Abaci Tolga , Thalmann Daniel
Published: November 2003

We present new techniques that use motion planning algorithms based on probabilistic roadmaps to control 22 degrees of freedom (DOFs) of human‐like characters in interactive applications. Our main purpose is the automatic synthesis of collision‐free reaching motions for both arms, with automatic column control and leg flexion. Generated motions are collision‐free, in equilibrium, and respect articulation range limits. In order to deal with the high (22) dimension of our configuration space, we bias the random distribution of configurations to favor postures most useful for reaching and grasping. In addition, extensions are presented in order to interactively generate object manipulation sequences: a probabilistic inverse kinematics solver for proposing goal postures matching pre‐designed grasps; dynamic update of roadmaps when obstacles change position; online planning of object location transfer; and an automatic stepping control to enlarge the character's reachable space. This is, to our knowledge, the first time probabilistic planning techniques are used to automatically generate collision‐free reaching motions involving the entire body of a human‐like character at interactive frame rates.

Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism
Hierarchical and Heterogenous Reactive Agents for Real‐Time Applications
Authors: Niederberger C. , Gross M.
Published: November 2003

We present a generic concept for autonomous agents with reactive behavior based on situation recognition in real‐time environments. Our approach facilitates behavior development through specialization of existing behavior types or weighted multiple inheritance in order to create new types. Additionally, the system allows for the simultaneous generation of hierarchical and semi‐individual group organizations using specification and recursive or modulo‐based patterns. Our framework is designed to support the creation of large numbers of secondary characters with individual and group behavior in simulation environments such as game engines. The engine allows for the specification of a maximal time‐per‐run in order to guarantee a minimal and constant frame‐rate. We demonstrate the usefulness of our approach by various examples with up to hundreds of individuals.

Categories and Subject Descriptors (according to ACM CCS): 1.2.11 [Distributed Artificial Intelligence]: Multiagent systems, I.6.7 [Simulation Support Systems]: Environments
Hierarchical Context‐based Pixel Ordering
Authors: Bar‐Joseph Ziv , Cohen‐Or Daniel
Published: November 2003

We present a context‐based scanning algorithm which reorders the input image using a hierarchical representationof the image. Our algorithm optimally orders (permutes) the leaves corresponding to the pixels, by minimizing thesum of distances between neighboring pixels. The reordering results in an improved autocorrelation betweennearby pixels which leads to a smoother image. This allows us, for the first time, to improve image compressionrates using context‐based scans. The results presented in this paper greatly improve upon previous work in bothcompression rate and running time.

Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Computational Geometryand Object Modeling I.3.6 [Computer Graphics]: Methodology and Techniques
Rendering and Affect
Authors: Duke D.J. , Barnard P.J. , Halper N. , Mellin M.
Published: November 2003

Previous studies at the intersection between rendering and psychology have concentrated on issues such as realismand acuity. Although such results have been useful in informing development of realistic rendering techniques,studies have shown that the interpretation of images is influenced by factors that have little to do with realism. Inthis paper, we summarize a series of experiments, the most recent of which are reported in a separate paper, thatinvestigate affective (emotive) qualities of images. These demonstrate significant effects that can be utilized withininteractive graphics, particularly via non‐photorealistic rendering (NPR). We explain how the interpretation ofthese results requires a high‐level model of cognitive information processing, and use such a model to account forrecent empirical results on rendering and judgement.

Categories and Subject Descriptors (according to ACM CCS): I.3.m [Computer Graphics]: Miscellaneous
A Few Good Lines: Suggestive Drawing of 3D Models
Authors: Sousa Mario Costa , Prusinkiewicz Przemyslaw
Published: November 2003

We present a method for rendering 3D models in the traditionalline‐drawing style used in artistic and scientificillustrations. The goal is to suggest the 3D shape of the objectsusing a small number of lines drawn with carefullychosen line qualities. The system combines several known techniquesinto a simple yet effective non‐photorealisticline renderer. Feature edges related to the outline and interiorof a given 3D mesh are extracted, segmented, andsmoothed, yielding chains of lines with varying path, length, thickness,gaps, and enclosures. The paper includessample renderings obtained for a variety of models.
Realistic Animation of Fluid with Splash and Foam
Authors: Takahashi Tsunemi , Fujii Hiroko , Kunimatsu Atsushi , Hiwada Kazuhiro , Saito Takahiro , Tanaka Ken , Ueki Heihachi
Published: November 2003

In this paper we describe a method for modeling and rendering dynamic behavior of fluids withsplashes and foam. A particle system is built into a fluid simulation system to represent an ocean wavecresting and spraying over another object. We use the Cubic Interpolated Propagation (CIP) method asthe fluid solver. The CIP method can solve liquid and gas together in the framework of fluid dynamicsand has high accuracy in the case of relatively coarse grids. This enables us to simulate the fluids in ashort time and describe the motion of splashes in the air that is associated with the liquid motion well.The foam floating on the water also can be described using the particle system. We integrate the rigidbody simulation with the fluid and particle system to create sophisticated scenes including splashes andfoam. We construct state change rules that are used with the particle system. This controls the generation,vanishing and transition rule of splashes and foam. The transition rule makes the seamless connection betweena splash and foam. We employed a fast volume rendering method with scattering effect for particles.One of the important features of our method is the combination of fast simulation and rendering techniques,which provides dynamic and realistic scenes in a short time.
Particle‐Based Simulation of Fluids
Authors: Premžoe Simon , Tasdizen Tolga , Bigler James , Lefohn Aaron , Whitaker Ross T.
Published: November 2003

Due to our familiarity with how fluids move and interact, as well as their complexity, plausible animation of fluidsremains a challenging problem. We present a particle interaction method for simulating fluids. The underlyingequations of fluid motion are discretized using moving particles and their interactions. The method allows simulationand modeling of mixing fluids with different physical properties, fluid interactions with stationary objects, andfluids that exhibit significant interface breakup and fragmentation. The gridless computational method is suitedfor medium scale problems since computational elements exist only where needed. The method fits well into thecurrent user interaction paradigm and allows easy user control over the desired fluid motion.
Animating Hair with Loosely Connected Particles
Authors: Bando Yosuke , Chen Bing‐Yu , Nishita Tomoyuki
Published: November 2003

This paper presents a practical approach to the animation of hair at an interactive frame rate. In our approach,we model the hair as a set of particles that serve as sampling points for the volume of the hair, which covers thewhole region where hair is present. The dynamics of the hair, including hair‐hair interactions, is simulated usingthe interacting particles. The novelty of this approach is that, as opposed to the traditional way of modeling hair,we release the particles from tight structures that are usually used to represent hair strands or clusters. Therefore,by making the connections between the particles loose while maintaining their overall stiffness, the hair can bedynamically split and merged during lateral motion without losing its lengthwise coherence.

Categories and Subject Descriptions (according to ACM CCS): I.3.7 [Computer Graphics]: Three‐DimensionalGraphics and Realism, I.3.3 [Computer Graphics]: Picture/Image Generation
Adaptive Logarithmic Mapping For Displaying High Contrast Scenes
Authors: Drago F. , Myszkowski K. , Annen T. , Chiba N.
Published: November 2003

We propose a fast, high quality tone mapping technique to display high contrast images on devices with limited dynamicrange of luminance values. The method is based on logarithmic compression of luminance values, imitatingthe human response to light. A bias power function is introduced to adaptively vary logarithmic bases, resultingin good preservation of details and contrast. To improve contrast in dark areas, changes to the gamma correctionprocedure are proposed. Our adaptive logarithmic mapping technique is capable of producing perceptually tunedimages with high dynamic content and works at interactive speed. We demonstrate a successful application of ourtone mapping technique with a high dynamic range video player enabling to adjust optimal viewing conditions forany kind of display while taking into account user preference concerning brightness, contrast compression, anddetail reproduction.

Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Image Processing and Computer Vision]: Image Representation
Image Categorization using Color Blobs in a Mobile Environment
Authors: Gavilan Ruiz David , Takahashi Hiroki , Nakajima Masayuki
Published: November 2003

This paper generalizes the basic idea of blobs in preattentive perception using color information. This is usedas the base of a basic classification of low resolution pictures taken with mobile phones. This classification, theblob‐like representation of the image and other information in user's context, such as GPS information, can beused in the presented framework as the basis of a new graphical interface for HCI (Human Computer Interaction).Similar systems whether they work with global properties of the image, which leads to inaccurate results, or withcomplex segmentation process that fails to capture expected objects in the scene. Most of those systems do notpay attention on other information involved in the creation of the image, such as time or location. We describe asystem which uses geographical information associated with a picture in a mobile phone terminal, and with a fastsegmentation based on color categorization.
Shadow Volumes on Programmable Graphics Hardware
Authors: Brabec Stefan , Seidel Hans‐Peter
Published: November 2003

One of the best choices for fast, high quality shadows is the shadow volume algorithm. However, for real timeapplications the extraction of silhouette edges can significantly burden the CPU, especially with highly tessellatedinput geometry or when complex geometry shaders are applied.

In this paper we show how this last, expensive part of the shadow volume method can be implemented on programmablegraphics hardware. This way, the originally hybrid shadow volumes algorithm can now be reformulatedas a purely hardware‐accelerated approach.

The benefits of this implementation is not only the increase in speed. Firstly, all computations now run on thesame hardware resulting in consistent precision within all steps of the algorithm. Secondly, programmable vertextransformations are no longer problematic when applied to shadow casting objects.

Categories and Subject Descriptors (according to ACM CCS): I.3.1 [Computer Graphics]: Hardware Architecture;I.3.3 [Computer Graphics]: Picture/Image Generation; I.3.7 [Computer Graphics]: Three‐Dimensional Graphicsand Realism
Solving Geometric Optimization Problems using Graphics Hardware
Authors: Denny Markus
Published: November 2003

We show how to use graphics hardware for tackling optimization problems arising in the field of computationalgeometry. We exemplarily discuss three problems, where combinatorial algorithms are inefficient or hard to implement.Given a set S of n point in the plane, the first two problems are to determine the smallest homotheticscaling of a star shaped polygon P enclosing S and to find the largest empty homothetic scaling of P completelycontained inside an arbitrary polygonal region. Pixel‐exact solutions for both problems are computed in real‐time.The third problem is a facility location problem and more difficult to solve. Given the Voronoi diagram VoD(S) ofthe n points, we try to position another point p in the plane, such that the resulting Voronoi region of p has maximalarea. As far as we know there exists no traditional solution for this problem for which we present pixel‐exactsolutions.

Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Geometric algorithms,languages, and systems I.3.3 [Computer Graphics]: Display algorithms
Automatic texture atlas generation from trimmed NURBS models
Authors: Guthe M. , Klein R.
Published: November 2003

A Texture Atlas is a two dimensional representation of a 3D model usable for paint systems or as a sewing pattern.The field of texture atlas generation from polygonal models has been well exploited in the recent years. The developedalgorithms work on piecewise linear surface representations, but not on parametric surfaces like NURBS,that are still the main surface representation in CAD systems. If a texture atlas is generated from a triangulatedNURBS model, the result cannot be edited further in a CAD system, since the separation into charts is not basedon the separate NURBS patches of the original model. We present a method for automatic generation of a textureatlas directly from trimmed NURBS models, while preserving the original NURBS representation. The resultingtexture atlas is build of several charts, each consisting of the original NURBS patches sewn together.

Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation;I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling; I.3.7 [Computer Graphics]: Three‐DimensionalGraphics and Realism — Color, Shading and Texture; J.6 [Computer‐aided Engineering]: Computer‐aideddesign (CAD)
Interactive Rendering with Bidirectional Texture Functions
Authors: Suykens Frank , Berge Karl , Lagae Ares , Dutré Philip
Published: November 2003

We propose a new technique for efficiently rendering bidirectional texture functions (BTFs). A 6D BTF describesthe appearance of a material as a texture that depends on the lighting and viewing directions. As such, a BTFaccommodates self‐shadowing, interreflection, and masking effects of a complex material without needing anexplicit representation of the small scale geometry. Our method represents the BTF as a set of spatially varyingapparent BRDFs, that each encode the reflectance field of a single pixel in the BTF. Each apparent BRDF isdecomposed into a product of three or more two‐dimensional positive factors using a novel factorization technique,which we call chained matrix factorization (CMF). The proposed factorization technique is fully automatic andsuitable for both BRDFs and apparent BRDFs (which typically exhibit off‐specular peaks and non‐reciprocity).The main benefit of CMF is that it delivers factors well suited for the limited dynamic range of conventionaltexture maps. After factorization, an efficient representation of the BTF is obtained by clustering the factors intoa compact set of 2D textures. With this compact representation, BTFs can be rendered on recent consumer levelhardware with arbitrary viewing and lighting directions at interactive rates.

Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three‐DimensionalGraphics and Realism
Planned Sampling of Spatially Varying BRDFs
Authors: Lensch Hendrik P.A. , Lang Jochen , Sá Asla M. , Seidel Hans‐Peter
Published: November 2003

Measuring reflection properties of a 3D object involves capturing images for numerous viewing and lightingdirections. We present a method to select advantageous measurement directions based on analyzing the estimationof the bi‐directional reflectance distribution function (BRDF). The selected directions minimize the uncertaintyin the estimated parameters of the BRDF. As a result, few measurements suffice to produce models that describethe reflectance behavior well. Moreover, the uncertainty measure can be computed fast on modern graphics cardsby exploiting their capability to render into a floating‐point frame buffer. This forms the basis of an acquisitionplanner capable of guiding experts and non‐experts alike through the BRDF acquisition process. We demonstratethat spatially varying reflection properties can be captured more efficiently for real‐world applications using ouracquisition planner.

Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three‐DimensionalGraphics and Realism Virtual Reality I.4.1 [Computer Vision]: Digitization and Image Capture, Reflectance
Ray Differentials and Multiresolution Geometry Caching for Distribution Ray Tracing in Complex Scenes
Authors: Christensen Per H. , Laur David M. , Fong Julia , Wooten Wayne L. , Batali Dana
Published: November 2003

When rendering only directly visible objects, ray tracing a few levels of specular reflection from large, low‐curvaturesurfaces, and ray tracing shadows from point‐like light sources, the accessed geometry is coherentand a geometry cache performs well. But in many other cases, the accessed geometry is incoherent and a standardgeometry cache performs poorly: ray tracing of specular reflection from highly curved surfaces, tracing rays thatare many reflection levels deep, and distribution ray tracing for wide glossy reflection, global illumination, widesoft shadows, and ambient occlusion. Fortunately, less geometric accuracy is necessary in the incoherent cases.This observation can be formalized by looking at the ray differentials for different types of scattering: coherentrays have small differentials, while incoherent rays have large differentials. We utilize this observation to obtainefficient multiresolution caching of geometry and textures (including displacement maps) for classic and distributionray tracing in complex scenes. We use an existing multiresolution caching scheme (originally developed forscanline rendering) for textures and displacement maps, and introduce a multiresolution geometry caching schemefor tessellated surfaces. The multiresolution geometry caching scheme makes it possible to efficiently render scenesthat, if fully tessellated, would use 100 times more memory than the geometry cache size.
Hierarchical Higher Order Face Cluster Radiosity for Global Illumination Walkthroughs of Complex Non‐Diffuse Environments
Authors: Gobbetti Enrico , Spanò Leonardo , Agus Marco
Published: November 2003

We present an algorithm for simulating global illumination in scenes composed of highly tessellated objects withdiffuse or moderately glossy reflectance. The solution method is a higher order extension of the face cluster radiositytechnique. It combines face clustering, multiresolution visibility, vector radiosity, and higher order baseswith a modified progressive shooting iteration to rapidly produce visually continuous solutions with limited memoryrequirements. The output of the method is a vector irradiance map that partitions input models into areaswhere global illumination is well approximated using the selected basis. The programming capabilities of moderncommodity graphics architectures are exploited to render illuminated models directly from the vector irradiancemap, exploiting hardware acceleration for approximating view dependent illumination during interactive walkthroughs.Using this algorithm, visually compelling global illumination solutions for scenes of over one millioninput polygons can be computed in minutes and examined interactively on common graphics personal computers.

Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture and Image Generation; I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism.
The Stringed Haptic Workbench: a New Haptic Workbench Solution
Authors: Tarrin N. , Coquillart S. , Hasegawa S. , Bouguila L. , Sato M.
Published: November 2003

The workbench is an interesting semi‐immersive configuration for interactive tasks. However, haptic feedback, i.e.force and tactile feedback, is one important cue which is missing. To the authors' knowledge, the sole proposedsolution consists in installing an arm force feedback device on one‐screen workbenches. This solution, however,has several drawbacks. The arm can perturb the stereoscopic display, cross virtual objects or hide parts of thevisualization space. Furthermore, the interaction space is limited by the size of the arm, which may also damagethe screen or perturb the electromagnetic tracking system. Some of these difficulties may even be worth with a two‐screenworkbench. This paper discusses an alternative solution, which consists in integrating a stringed hapticdevice on a workbench. This approach is less invasive, more flexible and well‐suited to a two‐screen workbench.
Adaptive Ray Tracing of Subdivision Surfaces
Authors: Müller Kerstin , Techmann Torsten , Fellner Dieter
Published: November 2003

Subdivision Surfaces as well as (interactive) ray tracing have become an important issue in computer graphics.But ray tracing of subdivision surfaces has received only little attention. We present a new approach for raytracing of subdivision surfaces. The algorithm uses a projection of the ray onto the surface and works mainly intwo dimensions along this projection. While proceeding from patch to patch, we examine the bounding volume oftheir borders: the lower the distance between ray and subdivision surface, the more refinement steps are adaptivelyapplied to the surface but only along the projection of the ray. The adaptive refinement of a patch is controlled bycurvature, size, its membership to the silhouette, and its potential contribution to the light transport. The algorithmis simple and mainly consists of elementary geometric computations. Hence it is fast and easy to implementwithout the need for elaborate preprocessing. The algorithm is robust in the sense that it deals with all features ofsubdivision surfaces like creases and corners.

Categories and Subject Descripters (according to ACM CCS): I.3.7 [Computer Graphics]: Raytracing
Image Based Interactive Rendering with View Dependent Geometry
Authors: Evers‐Senne J.‐F. , Koch R.
Published: November 2003

In this paper we present a novel approach for interactive rendering of virtual views from real image sequences.Combining the concepts of light fields, depth‐compensated image warping and view dependent texture mapping,this plenoptic modeling approach can handle large and complex scenes. A portable, handheld multi‐camera systemhas been developed that allows to record multiple image streams by simply walking around the scene. Theseimage streams are automatically calibrated and depth maps for all views are generated as input to the renderingstage. For rendering a view dependent warping surface is constructed on the fly and depth‐compensated imageinterpolation is applied with view‐dependent texture mapping. Rendering quality is scalable to allow fast previewand to achieve high‐end quality with the same approach. The system can handle large and geometrically complexscenes with hundreds of real images at interactive rates.

Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Viewing algorithms, I.4.1[Image Processing and Computer Vision]: Digitization and Image Capture, I.4.8 [Image Processing and ComputerVision]: Scene Analysis
Interactive Design of Bonsai Tree Models
Authors: Boudon Frédéric , Prusinkiewicz Przemyslaw , Federl Pavol , Godin Christophe , Karwowski Radoslaw
Published: November 2003

Because of their complexity, plant models used in computer graphics are commonly created with proceduralmethods. A difficult problem is the user control of these models: a small number of parameters is insufficient tospecify plant characteristics in detail, while large numbers of parameters are tedious to manipulate and difficultto comprehend. To address this problem, we propose a method for managing parameters involved in plant modelmanipulation. Specifically, we introduce decomposition graphs as multiscale representations of plant structuresand present interactive tools for designing trees that operate on decomposition graphs. The supported operationsinclude browsing of the parameter space, editing of generalized parameters (scalars, functions, and branchingsystem silhouettes), and the definition of dependencies between parameters. We illustrate our method by creatingmodels of bonsai trees.

Categories and Subject Descriptors (according to ACM CCS): I.3.6 [Computer Graphics]: Methodology and Techniques
A Fast Rendering Method for Refractive and Reflective Caustics Due to Water Surfaces
Authors: Iwasaki Kei , Dobashi Yoshinori , Nishita Tomoyuki
Published: November 2003

In order to synthesize realistic images of scenes that include water surfaces, the rendering of optical effectscaused by waves on the water surface, such as caustics and reflection, is necessary. However, rendering causticsis quite complex and time‐consuming. In recent years, the performance of graphics hardware has made significantprogress. This fact encourages researchers to study the acceleration of realistic image synthesis. We present herea method for the fast rendering of refractive and reflective caustics due to water surfaces. In the proposed method,an object is expressed by a set of texture mapped slices. We calculate the intensities of the caustics on the objectby using the slices and store the intensities as textures. This makes it possible to render caustics at interactive rateby using graphics hardware. Moreover, we render objects that are reflected and refracted due to the water surfaceby using reflection/refraction mapping of these slices.

Categories and Subject Descriptors (according to ACM CCS): I.3.1 [Computer Graphics]: Hardware Architecture I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism
Real‐Time Caustics
Authors: Wand M. , Straßer W.
Published: November 2003

We present a new algorithm to render caustics. The algorithm discretizes the specular surfaces into samplepoints. Each of the sample points is treated as a pinhole camera that projects an image of the incoming lightonto the diffuse receiver surfaces. Anti‐aliasing is performed by considering the local surface curvature at thesample points to filter the projected images. The algorithm can be implemented using programmable texturemapping hardware. It allows to render caustics in fully dynamic scenes in real‐time on current PC hardware.

Categories and Subject Descriptors: I.3.3 [Computer Graphics]: Picture/Image Generation — Display Algorithms;I.3.7 [Computer Graphics]: Three‐Dimensional Graphics and Realism