WSCG '2005: Full Papers

Permanent URI for this collection

Browse

Recent Submissions

Showing 1 - 20 out of 31 results
  • Item
    Dynamic coordinated email visualization
    (UNION Agency, 2005) Frau, Simone; Roberts, Jonathan C.; Boukhelifa, Nadia; Skala, Václav
    Many computer users receive hundreds (if not thousands) of emails per week; users often keep these emails and have many years of personal emails archived: users use their stored emails to manage appointments, to-do lists, and store useful information. In this paper we present an interactive email visualization tool (Mailview) that utilizes filter and coordination techniques to explore this archived data. The tool enables users to analyze and visualize hundreds of stored emails, it displays the emails on time-dependent plots enabling users to observe trends over time and perceive emails with similar features. Interaction is an important aspect of finding meaning within information, hence the tool utilizes focus+context views, dynamic filters, detail-on-demand techniques and coordinated views, finally, we discuss various methods that enable the system to be designed such that it can display hundreds of objects at interactive rates.
  • Item
    A Multi-Scale Singularity Bounding Volume Hierarchy
    (UNION Agency, 2005) Somchaipeng, Kerawit; Erleben, Keeny; Sporring, Jan; Skala, Václav
    A scale space approach is taken for building Bounding Volume Hierarchies (BVHs) for collision detection. A spherical bounding volume is generated at each node of the BVH using estimates of the mass distribution. Traditional top-down methods approximates the surface of an object in a coarse to fine manner, by recursively increasing resolution by some factor, e.g. 2. The method presented in this article analyzes the mass distribution of a solid object using a well founded scale-space based on the Diffusion Equation: the Gaussian Scale-Space. In the Gaussian scale-space, the deep structure of extremal mass points is naturally binary, and the linking process is therefore simple. The main contribution of this article is a novel approach for constructing BVHs using Multi-Scale Singularity Trees (MSSTs) for collision detection. The BVH-building algorithm extends the field with a new method based on volumetric shape rather than statistics of the surface geometry or geometrical constructs such as medial surfaces.
  • Item
    Achieving Consistency in a Combined IK/FK Interface for a Seven Degree-of-Freedom Kinematic Chain
    (UNION Agency, 2005) McDonald, John; Wolfe, Rosalee; Alkoby, Karen; Brzezinski, Jaceck; Carter, Roymieco; Davidson, Mary Jo; Furst, Jacob; Hinkle, Damien; Kroll, Bret; Lancaster, Glenn; Smallwood, Lori; Toro, Jorge; Ougouag, Nedjla; Schnepp, Jerry; Skala, Václav
    Many applications in computer animation portray the motion of a human arm and torso. Often such applications can benefit from a combination of Inverse (IK) and Forward (FK) Kinematics controls to manipulate the arms of the model. The human arm is a kinematic chain with seven degrees of freedom. The previous analytic solution to this kinematic chain gives highly detailed IK controls, but problems arise when integrating it with FK controls. These problems impede the artistic process when creating expressive animations. This work improves on the previous analytic solution to create a hybrid FK/IK control interface for manipulating the chain, and enables the recalculation of all the parameters necessary for the IK solution. Thus IK and FK controls can interact seamlessly to manipulate the arm. The torso is modeled as a separate kinematic chain, and is integrated with the arm linkages. User tests demonstrate the effectiveness and efficiency of the combined FK/IK control interface.
  • Item
    Feature Preserving Volumetric Data Simplification for Application in Medical Imaging
    (UNION Agency, 2005) Jin, C.; Fevens, T.; Li, S.; Mudur, S. P.; Skala, Václav
    In this paper, we propose a new simplification algorithm to reduce the large amount of redundancy in 3D medical image datasets and generate a new representation in tetrahedral meshes with considerably lower storage requirements. In the proposed algorithm, we first apply level set segmentation to partition the volume data into several homogenous sub-regions. We consider the interior boundaries between sub-regions as contributing more to the significant visible features. Next we convert the regular grid data into a tetrahedral representation and simplify the irregular volume representation by iteratively removing tetrahedra without significantly altering the exterior boundary or interior field distribution features. Within each sub-region, field gradients, tetrahedral aspect ratio changes and variances of interior region values are further used so as to maintain features of the original dataset in regional interiors. We tested our algorithm on several 3D medical datasets. The promising results show that we reduce redundancy and yet preserve important features and structures present in the original data set for decimation rates up to 50%.
  • Item
    Constructing Smooth Non-Manifold Meshes of Multi-Labeled Volumetric Datasets
    (UNION Agency, 2005) Reitinger, Bernhard; Bornik, Alexander; Beichel, Reinhard; Skala, Václav
    This paper presents a method for constructing consistent non-manifold meshes of multi-labeled volu- metric datasets. This approach is di erent to traditional surface reconstruction algorithms which often only support extracting 2-manifold surfaces based on a binary voxel classi cation. However, in some { especially medical { applications, multi-labeled datasets, where up to eight di erently labeled voxels can be adjacent, are subject to visualization resulting in non-manifold meshes. In addition to an e cient surface reconstruction method, a constrained geometric lter is developed which can be applied to these non-manifold meshes without producing ridges at mesh junctions.
  • Item
    Construction of Implicit Complexes: A Case Study
    (UNION Agency, 2005) Kartasheva, E.; Adzhiev, V.; Comninos, P.; Pasko, V.; Schmitt, B.; Skala, Václav
    This paper presents a detailed description of a case-study demonstrating a novel method for modelling and rendering of heterogeneous objects containing entities of various dimensionalities within a cellular-functional framework based on the implicit complex notion. Implicit complexes make it possible to combine a cellular representation and a constructive function representation. We briefly describe a formal framework for such a hybrid representation as well as a general structure for implicit complexes. Then, using a representative example, we show how an implicit complex can be constructed geometrically and topologically. We also consider the main rendering issues specific to implicit complexes and describe some implementation problems.
  • Item
    A Motion Constrained Dynamic Path Planning Algorithm for Multi-Agent Simulations
    (UNION Agency, 2005) Wan, T. R.; Chen, T.; Earnshaw, R. A.; Skala, Václav
    In this paper, we present a novel motion-orientated path planning algorithm fo r real-time navigation of mobile agents. The algorithm works well in dynamical and un-configured environments, and is able to produce a collision-free, time -optimal motion trajectory in order to find a navigation path. In addition to the motion constraint path planning, our approach can deal with the unknown obstacle-space terrains to moving agents. It therefore solves the drawbacks of traditional obstacle-space configuration methods. Multi-agent behaviour has been explored based on the algorithm. In the simulation a simple physically-based aircraft model has been developed, which is addressing the manoeuvring capabilities of the moving agents, while the moving agents' accelerations and velocities are always continuous and bounded. The generated motion path is constituted smoothly and has continuous curvature on the whole state space of the motion, thus satisfying the major requirement for the implementation of such strategies in real-time animation or in simulation applications in VR environments.
  • Item
    Enhancing Visual Exploration by Appropriate Color Coding
    (UNION Agency, 2005) Schulze-Wollgast, Petra; Tominski, Christian; Schumann, Heidrun; Skala, Václav
    Visualization is an effective means for exploring and analyzing complex data. Color coding is a fundamental technique for mapping data to visual representations. Although color coding is widely used in a large variety of visualizations, it is often provided in a limited way only or it is not used effectively. Therefore, we describe in this paper how appropriate (automatic) color coding can enhance the visual exploration of spatial-temporal data. We demonstrate our techniques with a system for visualizing human health data by means of choropleth maps. Furthermore, we focus on how to use color coding for facilitating comparison tasks in visualization.
  • Item
    Cellular Automata for 3D Morphing of Volume Data
    (UNION Agency, 2005) Semwal, S. K.; Chandrashekhar, K.; Skala, Václav
    Morphing involves the smooth transformation of one model, called the source to another, called the target. Several methods have been employed in this field both for two and three dimensional morphing. This paper performs morphing through the usage of cellular automata. The goal was to develop morphing algorithms that would minimize the need for both the user input and correspondence specification between source and the target. Two algorithms, the bacterial growth model and the core increment model have been designed and implemented in C++. Both algorithms utilize simple automata rules and are stable over dissimilar data. Results are presented that display the efficiency of the approach.
  • Item
    Interpolation Search for Point Cloud Intersection
    (UNION Agency, 2005) Klein, Jan; Zachmann, Gabriel; Skala, Václav
    We present a novel algorithm to compute intersections of two point clouds. It can be used to detect collisions between implicit surfaces defined by two point sets, or to construct their intersection curves. Our approach utilizes a proximity graph that allows for quick interpolation search of a common zero of the two implicit functions. First, pairs of points from one point set are constructed, bracketing the intersection with the other surface. Second, an interpolation search along shortest paths in the graph is performed. Third, the solutions are refined. For the first and third step, randomized sampling is utilized. We show that the number of evaluations of the implicit function and the overall runtime is in O(log logN), where N is the point cloud size. The storage is bounded by O(N). Our measurements show that we achieve a speedup by an order of magnitude compared to a recently proposed randomized sampling technique for point cloud collision detection.
  • Item
    Novel Path Search Algorithm for Image Stitching and Advanced Texture Tiling
    (UNION Agency, 2005) Somol, Petr; Haindl, Michal; Skala, Václav
    We propose a fast and adjustable sub-optimal path search algorithm for finding minimum error boundaries between overlapping images. The algorithm may serve as an efficient alternative to traditional slow path search algorithms like the dynamical programming. We use the algorithm in combination with novel adaptive blending to stitch image regions. The technique is then exploited in a framework for sampling-based texture synthesis where the learning phase is clearly separated and the synthesis phase is very simple and fast. The approach exploits the potential of tile-based texturing and produces good and realistic results for a wide range of textures.
  • Item
    Virtual Destruction of a 3D Object with a Stick
    (UNION Agency, 2005) Miyazaki, Tohru; Kaneko, Toyohisa; Kuriyama, Shigeru; Skala, Václav
    This paper is concerned with a real-time method for realizing virtual destruction of a 3D object with external force. A target object is a soft tofu (bean curd) cube which is easily destructable or breakable with a stick. A spring-mass network model is used to represent such an object. Destruction is realized by cutting a spring when its length exceeds its maximum length due to excess stretch force. A system was implemented on a PC with 2 CPU’s and a PHANToM, a force feedback device. A set of optimal parameters are experimentally identified. It is concluded that real-time destruction realized with the presented method can provide destruction close to real one.
  • Item
    Implementing Multi-Viewer Stereo Displays
    (UNION Agency, 2005) Fröhlich, Bernd; Hochstrate, Jan; Hoffmann, Jörg; Klüger, Karsten; Blach, Roland; Bues, Matthias; Stefani, Oliver; Skala, Václav
    In this paper we describe our implementations of multi-user stereo systems based on shuttered LCD-projectors and polarization. The combination of these separation techniques allows the presentation of more than one stereoscopic view on a single projection screen. We built two shutter configurations and designed a combined LC-shutter/polarization setup. Our first test setup was a combination of mechanical shutters for the projectors with liquid crystal (LC) shutters for the users’ eyes. The second configuration used LC-shutters only. Based on these configurations we have successfully implemented shuttering of four projectors to support two users with individual perspectively correct stereoscopic views. To improve brightness conditions and to increase the number of simultaneous users, we have designed a combined LC-shutter/polarization filter based projection system, which shows the most promising properties for real world applications.
  • Item
    The SenStylus: A Novel Rumble-Feedback Pen Device for CAD Application in Virtual Reality
    (UNION Agency, 2005) Fiorentino, Michele; Uva, Antonio E.; Monno, Giuseppe; Skala, Václav
    We have developed a pen device for CAD applications in virtual reality which provides novel features compared to existing systems. The SenStylus consists of a wireless pen designed to be ergonomically handled by the user for spatial interaction using a six degree of freedom optical tracking. In addition to the classic digital button(s) input, it provides analog multi-axial control, and a dual-rumble feedback output. We have integrated the device into an existing virtual reality CAD environment and extended the application functionalities with new devicespecific features. The SenStylus vibration feedback improves perception in the virtual world by controlling frequency, amplitude, and duration of the feedback, simulating a variety of responses during collisions and selection tasks. This capability enforces the visual depth sensitivity, which is critical when wo rking with complex CAD models. The multi-axial analog input provides a natural interaction paradigm to the user, thus simulating pen pressure and angle as in real world sketching and in real clay modeling. Dynamic tool-tip dimensioning and shaping are implemented as extra features. We present some applications to prove the added value of the SenStylus. The evaluation of the device received positive feedback by designers and engineers alike. The new features offered by this device can easily be extended to other VR applications using the API provided.
  • Item
    Motion Retargeting for the Hand Gesture
    (UNION Agency, 2005) Ge, Chunbao; Chen, Yiqiang; Yang, Changshui; Yin, Baocai; Gao, Wen; Skala, Václav
    This paper presents a new technique for retargeting the sign language data captured from motion capture device to different characters with different sizes and proportions. Realistic and natural animations can be produced to express similar meanings to the original. The proposed method first defines many sensitive points on the human body and selects the key sensitive points through analyzing the importance of the sensitive points. Next a novel mapping method based on relative position is presented to adapt the original sensitive points to the target sensitive points. Finally we utilize an IK solver to realize the retargeting problem. Experimental results show that the proposed method dramatically improves the recognition rate about 30%.
  • Item
    Simulation-Based Cartoon Hair Animation
    (UNION Agency, 2005) Sugisaki, Eiji; Yu, Yizhou; Anjyo, Ken; Morishima, Shigeo; Skala, Václav
    This paper describes a new hybrid technique for cartoon hair animation, one that allows the animators to create attractive and controllable hair animations without having to draw everything by hand except a sparse set of key frames. We demonstrate how to give a cel animation character accentuated hair motion. The novelty of this approach is that we neither simply interpolate the key frames nor generate the movement of the hair only using physical simulations. From a small number of rough sketches we prepare key frames that are used as indicators of hair motion. The hair movements are created based on a hair motion database built from physical simulations custom-designed by the animator. Hair animations with constraints from the key frames can be generated in two stages: a matching process to search for the desired motion sequences from the database and then smoothly connect them; the discrepancies between the database sequences and the key frames are interpolated throughoutthe animation using transition function.
  • Item
    Anisotropic Sampling for Differential Point Rendering of Implicit Surfaces
    (UNION Agency, 2005) Levet, Florian; Hadim, Julien; Reuter, Patrick; Schlick, Christophe; Skala, Václav
    In this paper, we propose a solution to adapt the differential point rendering technique developed by Kalaiah and Varshney to implicit surfaces. Differential point rendering was initially designed for parametric surfaces as a twostage sampling process that strongly relies on an adjacency relationship for the samples, which does not naturally exist for implicit surfaces. This fact made it particularly challenging to adapt the technique to implicit surfaces. To overcome this difficulty, we extended the particle sampling technique developed by Witkin and Heckbert in order to locally account for the principal directions of curvatures of the implicit surface. The final result of our process is a curvature driven anisotropic sampling where each sample ”rules” a rectangular or elliptical surrounding domain and is oriented according to the directions of maximal and minimal curvatures. As in the differential point rendering technique, these samples can then be efficiently rendered using a specific shader on a programmable GPU.
  • Item
    A Subdivision Scheme to Model Surfaces with Spherelike Features
    (UNION Agency, 2005) Beets, Koan; Claes, Johan; Van Reeth, Frank; Skala, Václav
    In this paper, we introduce a novel subdivision method able to generate smooth surfaces which locally tend to minimize variations in curvature. The method is based on a tensor product of a subdivision scheme for circle splines, which is then generalized to arbitrary quadrilateral meshes. Although they involve a geometric construction, our rules are applied in a uniform way, without the need for applying different rules for different vertices or for different stages in the subdivision process. This results in a more general and natural way to obtain circular curvatures, unlike other approaches involving subdivision curves able to generate circles. Surfaces of revolution are just a basic example, as circular features can be distributed freely over the surfaces generated via our methods.
  • Item
    New spectral decomposition for 3D polygonal meshes and its application to watermarking
    (UNION Agency, 2005) Murotani, Kohei; Sugihara, Kokichi; Skala, Václav
    This paper present a generalization of a data analysis technique called a singular spectrum analysis (SSA). The original SSA is a tool for analyzing one-dimensional data such as time series, whereas our generalization is suitable for multi-dimensional data such as 3D polygonal meshes. One of applications of the proposed generalization are also shown. The application of the generalized SSA is a new robust watermarking method that adds a watermark to a 3D polygonal mesh. Watermarks embedded by our method are resistant to similarity transformations and random noises. Our method has the advantage in that it requires smaller calculation cost than other methods with nearly equal performance.
  • Item
    Coherent and Exact PolygontoPolygon Visibility
    (UNION Agency, 2005) Mora, F.; Aveneau, L.; Mériaux, M.; Skala, Václav
    Visibility computation is a classical problem in computer graphics. A wide variety of algorithms provides solutions with a different accuracy. However, the four dimensional nature of the 3D visibility has prevented for a long time from leading to exact frompolygon visibility algorithms. Recently, the two first tractable solutions were presented by Nirenstein, then Bittner. Their works give the opportunity to design exact visibility tools for applications that require a high level of accuracy. This paper presents an approach that takes advantage of both Nirenstein and Bittner methods. On the one hand, it relies on an optimisation of Nirenstein’s algorithm that increases the visibility information coherence and the computation robustness. On the other hand, it provides an exact visibility data structure as Bittner does, but also suited for nonoriented polygontopolygon visibility queries.