Issue 3

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/111

Browse

Now showing 1 - 20 of 49

Adaptive Logarithmic Mapping For Displaying High Contrast Scenes
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Drago, F.; Myszkowski, K.; Annen, T.; Chiba, N.
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
Adaptive Ray Tracing of Subdivision Surfaces
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Müller, Kerstin; Techmann, Torsten; Fellner, Dieter W.
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
Advanced Design for a Realistic Virtual Brush
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Xu, Songhua; Lau, Francis C.M.; Tang, Feng; Pan, Yunhe
This paper proposes a novel algorithmic framework for an advanced virtual brush to be used in interactive digitalpainting. The framework comprises the following components: a geometry model of the brush using a hierarchicalrepresentation that leads to substantial savings in every step of the painting process; fast online brush motionsimulation assisted by offline calibration that guarantees an accurate and stable simulation of the brush's dynamicbehavior; a new pigment model based on a diffusion process of random molecules that considers delicateand complex pigment behavior at dipping time as well as during painting; and a user-adaptation component thatenables the system to cater for the personal painting habits of different users. A prototype system has been implementedbased on this framework. Compared with other virtual brushes, this new system is designed to presenta realistic brush in the sense that the system accurately and stably simulates the complex painting functionalityof a running brush, and therefore is capable of creating high-quality digital paintings with minute aesthetic detailsthat can rival the real artwork. The advanced features also give rise to a high degree of expressiveness ofthe virtual brush that the user can comfortably manipulate. http://www.csis.hku.hk/songhuale-brush/ providessupplementary materials for this paper.Categories and Subject Descriptors (according to ACM CCS): I.3.6 [Methodology and Techniques]: Interactiontechniques; I.3.5 [Computational Geometry and Object Modeling]: Physically based modeling; I.3.4 [GraphicsUtilities]: Paint systems;
Animating Hair with Loosely Connected Particles
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Bando, Yosuke; Chen, Bing-Yu; Nishita, Tomoyuki
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
Animation of Bubbles in Liquid
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Hong, Jeong-Mo; Kim, Chang-Hun
We present a new fluid animation technique in which liquid and gas interact with each other, using the exampleof bubbles rising in water. In contrast to previous studies which only focused on one fluid, our system considersboth the liquid and the gas simultaneously. In addition to the flowing motion, the interactions between liquid andgas cause buoyancy, surface tension, deformation and movement of the bubbles. For the natural manipulationof topological changes and the removal of the numerical diffusion, we combine the volume-of-fluid method andthe front-tracking method developed in the field of computational fluid dynamics. Our minimum-stress surfacetension method enables this complementary combination. The interfaces are constructed using the marching cubesalgorithm. Optical effects are rendered using vertex shader techniques.Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Animation
Automatic texture atlas generation from trimmed NURBS models
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Guthe, M.; Klein, R.
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)
BDAM - Batched Dynamic Adaptive Meshes for High Performance Terrain Visualization
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Cignoni, P.; Ganovelli, F.; Gobbetti, E.; Marton, F.; Ponchio, F.; Scopigno, R.
This paper describes an efficient technique for out-of-core rendering and management of large textured terrainsurfaces. The technique, called Batched Dynamic Adaptive Meshes (BDAM), is based on a paired tree structure:a tiled quadtree for texture data and a pair of bintrees of small triangular patches for the geometry. These smallpatches are TINs and are constructed and optimized off-line with high quality simplification and tristrippingalgorithms. Hierarchical view frustum culling and view-dependent texture and geometry refinement is performedat each frame through a stateless traversal algorithm. Thanks to the batched CPU/GPU communication model,the proposed technique is not processor intensive and fully harnesses the power of current graphics hardware.Both preprocessing and rendering exploit out-of-core techniques to be fully scalable and to manage large terraindatasets.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.
Beyond Stippling - Methods for Distributing Objects on the Plane
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Hiller, Stefan; Hellwig, Heino; Deussen, Oliver
Conventionally, stippling is an effective technique for representing surfaces in pen-and-ink. We present new efficientmethods for stipple drawings by computer. In contrast to already existing techniques, arbitrary shapes canbe used in place of dots. An extension of Lloyd's Method enables us to position small objects on a plane in a visuallypleasing form. This allows us to generate new illustration styles. Similar methods can be used for positioningobjects in other applications.
Cloth Motion Capture
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Pritchard, D.; Heidrich, W.
Recent years have seen an increased interest in motion capture systems. Current systems, however, are limitedto only a few degrees of freedom, so that effectively only the motion of linked rigid bodies can be acquired. Wepresent a system for the capture of deformable surfaces, most notably moving cloth, including both geometry andparameterisation. We recover geometry using stereo correspondence, and use the Scale Invariant Feature Transform(SIFT) to identify an arbitrary pattern printed on the cloth, even in the presence of fast motion. We describea novel seed-and-grow approach to adapt the SIFT algorithm to deformable geometry. Finally, we interpolatefeature points to parameterise the complete geometry.Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Physically based modelingI.4.8 [Image Processing and Computer Vision]: Scene analysis
Compression of 2D Vector Fields Under Guaranteed Topology Preservation
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Theisel, H.; Rossl, Ch.; Seidel, H.-P.
In this paper we introduce a new compression technique for 2D vector fields which preserves the complete topology, i.e., the critical points and the connectivity of the separatrices. As the theoretical foundation of the algorithm, we show in a theorem that for local modifications of a vector field, it is possible to decide entirely by a local analysis whether or not the global topology is preserved. This result is applied in a compression algorithm which is based on a repeated local modification of the vector field - namely a repeated edge collapse of the underlying piecewise linear domain. We apply the compression technique to a number of data sets with a complex topology and obtain significantly improved compression ratios in comparison to pre-existing topology-preserving techniques.
Fast Photo-Realistic Rendering of Trees in Daylight
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Qin, Xueying; Nakamae, Eihachiro; Tadamura, Katsumi; Nagai, Yasuo
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
A Fast Rendering Method for Refractive and Reflective Caustics Due to Water Surfaces
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Iwasaki, Kei; Dobashi, Yoshinori; Nishita, Tomoyuki
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
A Few Good Lines: Suggestive Drawing of 3D Models
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Sousa, Mario Costa; Prusinkiewicz, Przemyslaw
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.
Field Functions for Blending Range Controls on Soft Objects
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Hsu, P. C.; Lee, C.
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 regionCategories and Subject Descriptors (according to ACM CCS): I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling - Curve, surface, solid and object representations
Freeform Shape Representations for Efficient Geometry Processing
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Kobbelt, Leif
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.
Hierarchical and Heterogenous Reactive Agents for Real-Time Applications
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Niederberger, C.; Gross, M.
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
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Bar-Joseph, Ziv; Cohen-Or, Daniel
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
Hierarchical Higher Order Face Cluster Radiosity for Global Illumination Walkthroughs of Complex Non-Diffuse Environments
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Gobbetti, Enrico; Spano, Leonardo; Agus, Marco
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.
Image Based Interactive Rendering with View Dependent Geometry
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Evers-Senne, J.-F.; Koch, R.
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
Image Categorization using Color Blobs in a Mobile Environment
(Blackwell Publishers, Inc and the Eurographics Association, 2003) Gavilan Ruiz, David; Takahashi, Hiroki; Nakajima, Masayuki
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.

Browse

Browsing Issue 3 by Title

Results Per Page

Sort Options