EG2011
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Item Reconstruction of Cultural Heritage Object Utilizing its Paper Model for Augmented Reality(The Eurographics Association, 2011) Haladova, Zuzana; R. Laramee and I. S. LimAugmented reality is nowadays one of the most expanding fields of the computer graphics and the popularity of the cultural heritage AR applications increases as well. This project presents the reconstruction of the historical event with the augmented reality information added to the paper model of the heritage site. The application presents the fire of the Bojnice castle. The hardware used in the project consists of the web cam which records the scene with the castle and the computer which receives the record and produces the augmented experience. The two methods for the registration of the real model and the future work needed are presented.Item Guided ProceduralModeling(The Eurographics Association and Blackwell Publishing Ltd., 2011) Bene , Bedrich; tava, Ondrej; Mech, Radomir; Miller, Gavin; M. Chen and O. DeussenProcedural methods present one of the most powerful techniques for authoring a vast variety of computer graphics models. However, their massive applicability is hindered by the lack of control and a low predictability of the results. In the classical procedural modeling pipeline, the user usually defines a set of rules, executes the procedural system, and by examining the results attempts to infer what should be changed in the system definition in order to achieve the desired output. We present guided procedural modeling, a new approach that allows a high level of top-down control by breaking the system into smaller building blocks that communicate. In our work we generalize the concept of the environment. The user creates a set of guides. Each guide defines a region in which a specific procedural model operates. These guides are connected by a set of links that serve for message passing between the procedural models attached to each guide. The entire model consists of a set of guides with procedural models, a graph representing their connection, and the method in which the guides interact. The modeling process is performed by modifying each of the described elements. The user can control the high-level description by editing the guides or manipulate the low-level description by changing the procedural rules. Changing the connectivity allows the user to create new complex forms in an easy and intuitive way. We show several examples of procedural structures, including an ornamental pattern, a street layout, a bridge, and a model of trees. We also demonstrate interactive examples for quick and intuitive editing using physics-based mass-spring system.Item Methodologies for Connected Structured Idealized Ice Crystal Growth Models(The Eurographics Association, 2011) El-Alem, Yousef; Roberts, Jonathan C.; R. Laramee and I. S. LimIce crystals are beautiful and intricate shapes. Our goal is to create ice crystal and other models with similar structure and render them in three-dimensions. Many of the current algorithms apply complex physics-based simulation algorithms to simulate the crystal growth, most are two-dimensional forms, and importantly they are made up of many disconnected parts (pixels); consequently they cannot be easily stored as a single model. However, our approach is to generate visually appealing 3d structures, rather than accurately model reality, that are geometrically connected together to form one connected model. These idealized structures can be easily stored, manipulated and included with other 3d-models and into virtual environments. This work is part of a larger project, thus in this poster presentation we merely describe several alternative methodologies to achieve this effect.Item Synesthetic Sound-Color Cross-Modality in Animations(The Eurographics Association, 2011) Cai, D.; Goto, S.; Wang, J. P.; Asai, N.; Nagata, N.; Fukumoto, A.; Kurumizawa, J.; R. Laramee and I. S. LimCategories and Subject Descriptors (according to ACM CCS): H.5.1 [Information Interfaces And Presentation]: Multimedia Information Systems-Evaluation/methodologyItem Shape Analysis with Subspace Symmetries(The Eurographics Association and Blackwell Publishing Ltd., 2011) Berner, Alexander; Wand, Michael; Mitra, Niloy J.; Mewes, Daniel; Seidel, Hans-Peter; M. Chen and O. DeussenWe address the problem of partial symmetry detection, i.e., the identification of building blocks a complex shape is composed of. Previous techniques identify parts that relate to each other by simple rigid mappings, similarity transforms, or, more recently, intrinsic isometries. Our approach generalizes the notion of partial symmetries to more general deformations. We introduce subspace symmetries whereby we characterize similarity by requiring the set of symmetric parts to form a low dimensional shape space. We present an algorithm to discover subspace symmetries based on detecting linearly correlated correspondences among graphs of invariant features. We evaluate our technique on various data sets. We show that for models with pronounced surface features, subspace symmetries can be found fully automatically. For complicated cases, a small amount of user input is used to resolve ambiguities. Our technique computes dense correspondences that can subsequently be used in various applications, such as model repair and denoising.Item Accelerated 5D Ray Tree construction on the GPU(The Eurographics Association, 2011) Kammaje, Ravi P.; Mora, Benjamin; R. Laramee and I. S. LimRay tracing random rays has been a challenge. Due to their reduced coherence, the normal methods of acceleration like packet tracing that make use of coherence of the rays do not work well. These random rays are encountered in global illumination methods. 5D ray classification, first introduced by Arvo and Kirk [AK87], can classify these rays into coherent groups. We introduce a method that builds a hierarchical structure identifying coherence in random rays very quickly using the increased processing power of the GPU.Item High Performance Interactive Painting On The GPU(The Eurographics Association, 2011) Großer, M.; Wacker, M.; R. Laramee and I. S. LimThis paper addresses the problem of mapping between two different texture coordinate setups for one single mesh. We exploit the advantages of the render pipeline on the GPU to obtain interactive texture painting on an already textured mesh. The approach combines projection mapping with a render-to-texture technique in order to bake additional layers of texture or detail into a given texture. The benefit of our approach is high performance and complete independence of complexity of the object and the parametrization.Item Fruit Senescence and Decay Simulation(The Eurographics Association and Blackwell Publishing Ltd., 2011) Jr., Joseph T. Kider; Raja, Samantha; Badler, Norman I.; M. Chen and O. DeussenAging and imperfections provide important visual cues for realism. We present a novel physically-based approach for simulating the biological aging and decay process in fruits. This method simulates interactions between multiple processes. Our biologically-derived, reaction-diffusion model generates growth patterns for areas of fungal and bacterial infection. Fungal colony spread and propagation is affected by both bacterial growth and nutrient depletion. This process changes the physical properties of the surface of the fruit as well as its internal volume substrate. The fruit is physically simulated with parameters such as skin thickness and porosity, water content, flesh rigidity, ambient temperature, humidity, and proximity to other surfaces. Our model produces a simulation that closely mirrors the progression of decay in real fruits under similar parameterized conditions. Additionally, we provide a tool that allows artists to customize the input of the program to produce generalized fruit simulations.Item Photographically Guided Alignment for HDR Images(The Eurographics Association, 2011) Akyüzy, Ahmet Oguz; A. Day and R. Mantiuk and E. Reinhard and R. ScopignoThis paper presents an automatic image alignment algorithm that alleviates the need to keep the camera still during the capture of a bracketed sequence to obtain an HDR image. Our algorithm assumes that the misalignment between the two consecutive exposures is translational. Using a photographically guided random search, our algorithm first finds properly exposed high contrast regions. The shift amount is then found by analyzing and matching the pixel correlations inside these regions.Item Hatching for Motion Picture Production(The Eurographics Association and Blackwell Publishing Ltd., 2011) Umenhoffer, Tamás; Szécsi, László; Szirmay-Kalos, László; M. Chen and O. DeussenThis paper presents a hatching algorithm which - while also allows for an implementation in real-time - is integrated into the production pipeline of computer generated motion picture. Motion picture production pipelines impose special functional and quality requirements. From the functional point of view, the stages of modeling, 3D rendering, and compositing form a pipeline without feed-back, and frames are rendered independently, possibly on different computers. Thus, no temporal data can be shared between them while flicker free animation needs to be generated. Quality requirements can be grasped as that of dual consistency: the generated hatching must consistently follow object movement and deformation, and, at the same time, it should have a consistent pattern and density in image-space to provide the hand-crafted look. In order to meet both requirements, we apply a particle based method and develop an image-space density control mechanism using rejection sampling and low- discrepancy sequences. We also discuss the decomposition of rendering tasks according to the main stages of the production pipeline and demonstrate how the artist can define the illustration style in a convenient way.Item SQuad: Compact Representation for Triangle Meshes(The Eurographics Association and Blackwell Publishing Ltd., 2011) Gurung, Topraj; Laney, Daniel; Lindstrom, Peter; Rossignac, Jarek; M. Chen and O. DeussenThe SQuad data structure represents the connectivity of a triangle mesh by its "S table" of about 2 rpt (integer references per triangle). Yet it allows for a simple implementation of expected constant-time, random-access operators for traversing the mesh, including in-order traversal of the triangles incident upon a vertex. SQuad is more compact than the Corner Table (CT), which stores 6 rpt, and than the recently proposed SOT, which stores 3 rpt. However, in-core access is generally faster in CT than in SQuad, and SQuad requires rebuilding the S table if the connectivity is altered. The storage reduction and memory coherence opportunities it offers may help to reduce the frequency of page faults and cache misses when accessing elements of a mesh that does not fit in memory. We provide the details of a simple algorithm that builds the S table and of an optimized implementation of the SQuad operators.Item The Worst View for Virtual Museum Presentation(The Eurographics Association, 2011) Varhanikova, I.; Ferko, A.; R. Laramee and I. S. LimWe discuss the possibility of the worst view utilization in virtual environment (especially virtual museum). Our approach uses one of the possible method of finding the best view on virtual 3D objects. We use the junky material from this method to make the visit of the museum more interesting. We outline the possibilities and ways of using the worst view for virtual museums presentation.Item The Natural 3D Spiral(The Eurographics Association and Blackwell Publishing Ltd., 2011) Harary, Gur; Tal, Ayellet; M. Chen and O. DeussenLogarithmic spirals are ubiquitous in nature. This paper presents a novel mathematical definition of a 3D logarithmic spiral, which provides a proper description of objects found in nature. To motivate our work, we scanned spiral-shaped objects and studied their geometric properties. We consider the extent to which the existing 3D definitions capture these properties. We identify a property that is shared by the objects we investigated and is not satisfied by the existing 3D definitions. This leads us to present our definition in which both the radius of curvature and the radius of torsion change linearly along the curve. We prove that our spiral satisfies several desirable properties, including invariance to similarity transformations, smoothness, symmetry, extensibility, and roundness. Finally, we demonstrate the utility of our curves in the modeling of several animal structures.Item Estimating Color and Texture Parameters for Vector Graphics(The Eurographics Association and Blackwell Publishing Ltd., 2011) Jeschke, Stefan; Cline, David; Wonka, Peter; M. Chen and O. DeussenDiffusion curves are a powerful vector graphic representation that stores an image as a set of 2D Bezier curves with colors defined on either side. These colors are diffused over the image plane, resulting in smooth color regions as well as sharp boundaries. In this paper, we introduce a new automatic diffusion curve coloring algorithm. We start by defining a geometric heuristic for the maximum density of color control points along the image curves. Following this, we present a new algorithm to set the colors of these points so that the resulting diffused image is as close as possible to a source image in a least squares sense. We compare our coloring solution to the existing one which fails for textured regions, small features, and inaccurately placed curves. The second contribution of the paper is to extend the diffusion curve representation to include texture details based on Gabor noise. Like the curves themselves, the defined texture is resolution independent, and represented compactly. We define methods to automatically make an initial guess for the noise texure, and we provide intuitive manual controls to edit the parameters of the Gabor noise. Finally, we show that the diffusion curve representation itself extends to storing any number of attributes in an image, and we demonstrate this functionality with image stippling an hatching applications.Item Four Virtual Reality Simulations for Teaching Earth Sciences(The Eurographics Association, 2011) Aguilar-Sierra, Alejandro; Garduño-López, René; R. Laramee and I. S. LimIn a previous work we proposed a multidisciplinary methodology to produce interactive, virtual reality learning objects to be used in courses for Earth science undergraduate students. In this work we present four recent products from our Visual Laboratory for Earth Sciences at CCA, UNAM. This is a result of the contribution of computer science undergraduate students, computer graphics and visualization specialists and Earth scientists.We are using affordable modern technology, open source libraries and public domain data.Item Towards Mobile HDR Video(The Eurographics Association, 2011) Castro, T. K.; Chapiro, A.; Cicconet, M.; Velho, L.; A. Day and R. Mantiuk and E. Reinhard and R. ScopignoWe present a novel method for High Dynamic Range video where the critical phases of the pipeline are based on histograms. It is possible to achieve high framerates, since the algorithm generates one HDR frame per captured frame. Also, the method is of low computational cost, making it particularly suited for devices with less powerful processors. An implementation of the capture process for the Nokia N900 smartphone, using the recent FCam API, is detailed.Item The Tumor Therapy Manager and its Clinical Impact(The Eurographics Association, 2011) Rössling, Ivo; Dornheim, Jana; Dornheim, Lars; Boehm, Andreas; Preim, Bernhard; K. Buehler and A. VilanovaVisual exploration of CT and MRI datasets in clinical practice is still dominated by slice-based viewing. Volume rendering is now widely available but seen primarily as a tool for a fast overview, and only rarely as a visualization to directly support clinical decisions. Research projects aiming at advanced 3D visualizations, such as smart visibility and illustrative renderings, usually fail to meet clinical demands, since the visualizations are not dedicated to specific diagnostic or treatment planning questions. Moreover, they are unfamiliar to users who need reliable and familiar visualizations as a basis for their crucial decisions. Discussions with clinical practicians reveal that parameterization of visual effects is too cumbersome and resulting visualizations are often too complex. We describe and discuss long-term experiences on developing, testing, and refining image analysis and visualization techniques for ENT surgery planning based on CT data. While visual quality and a faithful rendition of spatial relations indeed are essential, it turned out to be superior to generate sequences of rather simple 3D visualizations directly supporting specific treatment questions instead of presenting many anatomic structures simultaneously. We report on the actual clinical use of the system and discuss how it changed the surgical planning workflow.Item Enhancing Image-Based Aging Approaches(The Eurographics Association, 2011) Clément, Olivier; Paquette, Eric; N. Avis and S. LefebvreModern video games and computer-animated movies exhibit extremely realistic synthetic images. To achieve such a level of realism, artists have to consider several characteristics including material appearance changes from object aging such as rust, bumps, dents, or simply dust. Since adding these details is time-consuming, several approaches have been proposed to ease the aging process and reduce related costs. In this paper, we address some problems and limitations from image based aging techniques by proposing extensions intended to widen their range of application. First, we present a new automatic positioning system that handles special orientation cases, thus increasing the overall controllability on the aging framework. Also, we propose an innovative process to better handle multiple texture colorations during the synthesis phase of image-based aging techniques.Item Warp-based Motion Compensation for Endoscopic Kymography(The Eurographics Association, 2011) Schneider, David C.; Hilsmann, Anna; Eisert, Peter; N. Avis and S. LefebvreEndoscopic videokymography is a method for visualizing the motion of the plica vocalis (vocal folds) for medical diagnosis. The diagnostic interpretability of a kymogram deteriorates if camera motion interferes with vocal fold motion, which is hard to avoid in practice. We propose an algorithm for compensating strong camera motion for videokymography. The approach is based on an image-based inverse warping scheme that can be stated as an optimization problem. The algorithm is parallelizable and real-time capable on the CPU. We discuss advantages of the image-based approach and address its use for approximate structure visualization of the endoscopic scene.Item Using Procedural Modelling as a Framework for Representing Style: An Example from Regency Architecture(The Eurographics Association, 2011) Calogero, Erica; Tyson, Nick; Arnold, David; Morris, David; A. Day and R. Mantiuk and E. Reinhard and R. ScopignoThis paper reports the use of shape grammars, as made available in CityEngine, to deconstruct six examples of Regency facades and uses them to form a reconstruction of Brunswick Square, in Brighton & Hove, UK. The aim of the research is to evaluate the potential for shape grammar rules to effectively encapsulate aspects of style in a formal, computational language. It is argued that such a system could both result in a stochastically based definition of Regency style with a measurable degree of certainty and enable the presentation of historical periods of history in a real-time virtual environment.