WSCG '2009: Communication Papers Proceedings
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Item Shape Transformation of Multiple Objects Using Slices(Václav Skala - UNION Agency, 2009) Yasmin, Shamima; Talib, Abdullah Zawawi; Min, Chen; Skala, Václav3D shape transformation is usually confined to transformation between a pair of objects. The objective of this paper is to look at shape transformation from a different perspective: instead of binding this concept between two objects, the technique is extended to the concept of incorporating the characteristics of a number of objects in one body at a time. Equal number of slices are generated from all objects. Slices may be parallel to each other or each slice may have different orientation. Traversal of a data along its longitudinal direction may generate slices which are differently oriented from each other. When multiple objects are transformed to one and is used as an influence shape, it also works as incorporating multiple influence shapes at a time during transformation between two objects. The paper shows the ease of implementation of this concept in sliced data and also discusses its extendibility.
Item 3D Modeling of Free-Form Object (Interpolation, Visualization and Volume Estimation)(Václav Skala - UNION Agency, 2009) Sisojevs, Aleksandrs; Krechetova, Katrina; Glazs, Alexandrs; Min, Chen; Skala, VáclavThis work describes an efficient method of 3D object modeling. The method is applied for solving biomedical engineering tasks. The method is based on interpolation model creation. The model is built using Coons surface basis. For further implementation of the model the Coons surface basis is transformed to Bezier surface model. This work also describes a method of volume estimation of the reconstructed 3D model. Example of practical implementation is solving various biomedical tasks.Item Fiberbundle-Based Visualization of a Stirred-Tank Flow(Václav Skala - UNION Agency, 2009) Benger, Werner; Ritter, Marcel; Acharya, Sumanta; Min, Chen; Skala, VáclavWe describe a novel approach to treat data from a complex numerical simulation in a unified environment using a generic data model for scientific visualization. The model is constructed out of building blocks in a hierarchical scheme of seven levels, out of which only three are exposed to the end-user. This generic scheme allows for a wide variety of input formats, and results in powerful capabilities to connect data. We review the theory of this data model, implementation aspects in our visualization environment, and its application to computational fluid dynamic simulation of flow in an impeller-stirred tank. The computational data are given as a velocity vector field and a scalar pressure field on a mesh consisting of 2088 blocks in curvilinear coordinates.Item Efficient Semiautomatic Segmentation of Plant Biological Objects Based on Live-wire Methods(Václav Skala - UNION Agency, 2009) Schoor, Wolfram; Seidl, Thomas; Bollenbeck, Felix; Seiffert, Udo; Preim, Bernhard; Mecke, Rüdiger; Min, Chen; Skala, VáclavThis paper presents a novel method for efficient semiautomatic multi-label segmentation of plant biological image data. The approach extends live-wire methods in order to facilitate exact user-steered segmentations for atlas generation. By integrating a segmentation-specific user interaction model into the live-wire formulation i) more exact segmentations, ii) increased computational efficiency, iii) without loss of generality are achieved. The concept of mutual influence of image feature based path costs and user input uncertainty are consistently combined. By incorporating user behavior into cost based delineation a more intuitive user interface is obtained also yielding in a more accurate segmentation. We introduce path-based methodologies, specific user interaction models and propose the combination of both of them. The purposefulness of the method is shown in an application comprising segmentation of histological section data supporting the generation of 3-D atlases.Item Conversion of biquadratic rational Bézier surfaces into patches of particular Dupin cyclides: the torus and the double sphere(Václav Skala - UNION Agency, 2009) Garnier, Lionel; Belbis, Bertrand; Foufou, Sebti; Min, Chen; Skala, VáclavToruses and double spheres are particular cases of Dupin cyclides. In this paper, we study the conversion of rational biquadratic B´ezier surfaces into Dupin cyclide patches. We give the conditions that the B´ezier surface should satisfy to be convertible, and present a new conversion algorithm to construct the torus or double sphere patch corresponding to a given Bézier surface, some conversion examples are illustrated and commented.Item Video-Based Bicycle Detection in Underground Scenarios(Václav Skala - UNION Agency, 2009) Beran, Vítězslav; Herout, Adam; Řezníček, Ivo; Min, Chen; Skala, VáclavAutomatic surveillance systems are an important emerging application of object detection algorithms in video. The nature of such systems implies several requirements on the used algorithms. Also, searching for less usual objects (in contrast to frontal human faces, car masks, etc.) is required, such as detection of bicycles. It appears that detection of such objects cannot be solved by just applying a standard statistical or other general detector, but by constructing a specialized detector composed of several standard image processing and object-detection techniques combined together ad hoc. A detector of bicycles in video data from standard low-resolution CCTV surveillance system is presented in this contribution. Bicycle detection approach covered by this paper aims to cope with highly-noisy low-resolution data, to use simple image-processing methods and to work in real time. Although the method itself does not constitute a generally usable object detector, it covers several interesting aspects which can be re-used in tasks similar to the given one. Low-level features extracted from the video used for wheel-candidate classification are described in detail. The system is applied and evaluated on real data and the results are discussed.Item Vision Aware Continuum Crowds(Václav Skala - UNION Agency, 2009) Lefer, Daniel; Min, Chen; Skala, VáclavCrowd simulation has received increasing attention for two decades because potential applications of crowd simulators can be found in various societal domains. The continuum crowd model puts all information related to the decision-making process in a single equation, which can then be solved by a Fast Marching Method approach. In this paper we propose several improvements to the continuum crowd model: a new governing equation, a new collision avoidance method, and, our major contribution, we add vision capabilities to the characters, thus making them able to collect new information about their surrounding environment and to reconsider path planning according to up-to-date data.Item A fast SAH-based construction of Octree(Václav Skala - UNION Agency, 2009) Yang, Xin; Xu, Duan-qing; Zhao, Lei; Min, Chen; Skala, VáclavRecent GPU ray tracers can already achieve performance competitive to that of their CPU counterparts. Nevertheless, these systems can not yet fully exploit the capabilities of modern GPUs and can only handle medium-sized, static scenes. We present an octree construction algorithm for the GPU that achieves real-time performance by heavily exploiting the hardware, which has been observed to give superior performance in ray tracing compared to other acceleration structures. We use streaming construction with the surface area heuristic (SAH) that significantly increase the coherence of memory accesses during construction of the octree.Item Generalized Roller(Václav Skala - UNION Agency, 2009) Haindl, Michal; Hatka, Martin; Min, Chen; Skala, VáclavThis paper describes a generalization of our previously published simple roller method for seamless enlargement of colour textures such as natural bidirectional texture functions (BTF) that realistically represent appearance of given material surfaces. The generalized roller allows automatic detection of major texture periodicity directions which do not need to be aligned with coordinate axes. The roller texture synthesis method is based on the overlapping tiling and subsequent minimum error boundary cut. One or several optimal double toroidal BTF patches are seamlessly repeated during the synthesis step. While the method allows only moderate texture compression it is extremely fast due to complete separation of the analytical step of the algorithm from the texture synthesis part. The method is universal and easily implementable in a graphical hardware for purpose of real-time rendering of any type of static or dynamic textures.Item Trajectory classification using HMMs(Václav Skala - UNION Agency, 2009) Mlích, Jozef; Zemčík, Pavel; Jiřík, Leoš; Min, Chen; Skala, VáclavThis paper focuses on evaluation of motion of objects through classification of their trajectories. The objects used for evaluation of the presented method are objects tracked in video sequence but the method is quite general and can be used for more general trajectories. The main potential application of the presented method is detection of abnormal behavior of humans, hand gesture detection and recognition, etc. Hidden Markov Models (HMMs) and Gaussian Mixture Models are used as the base of the the classification mechanism. The paper contains description of the method, description of experiments and their results, and conclusions.Item Point Cloud Rendering in FPGA(Václav Skala - UNION Agency, 2009) Zemčík, Pavel; Maršík, Pavel; Herout, Adam; Min, Chen; Skala, VáclavThis contribution describes recent development in ongoing work focused on point cloud rendering algorithm implementation usable in environments containing programmable or custom hardware. The approach described in this paper is based on the idea that direct point cloud rendering, which is in the principle not too complicated, can be efficiently implemented in programmable or custom hardware. Such implementation can be useful not only for its performance but especially for the possibility to include it into solutions that require 3D graphics output in non PC environments and in embedded solutions with low power consumption, etc. This contribution describes the overall approach and the current results.Item Improvement of the DOI Technique for De-Interlacing(Václav Skala - UNION Agency, 2009) Ran Kim, Kyeong; Lee, Byung Gook; Yoo, Hoon; Min, Chen; Skala, VáclavThis paper presents an improved method for the direction-oriented interpolation (DOI) method. The technique of DOI is considered to be a very strong tool for intraframe-based deinterlacing in the literature. However, the DOI still have a problem to use wrong edge direction. To remedy this problem, we embed three steps in the DOI method to interpolate missing lines more efficiently and robustly than existing methods. In the proposed method, the spatial direction vector (SDV) data are reused and processed to prevent them utilizing in next interpolation step, resulting in the more accurate de-interlacing method. We carry out experiments to compare the proposed method with the existing methods including the edge-based line averaging (ELA) and DOI. Experimental results show that the proposed method gives better performance in objective and subjective quality than the existing deinterlacing methods.Item Error-bounded GPU-supported terrain visualisation(Václav Skala - UNION Agency, 2009) Löffler, Falko; Rybacki, Stefan; Schumann, Heidrun; Min, Chen; Skala, VáclavThe interactive visualisation of digital terrain datasets deals with their interrelated issues: quality, time and resources. In this paper a GPU-supported rendering technique is introduced, which finds a tradeoff between these issues. For this we use the projective grid method as the foundation. Even though the method is simple and powerful, its most significant problem is the loss of relevant features. Our contribution is a definition of a view-dependent grid distribution on the view-plane and an error-bounded rendering. This leads to a better approximation of the original terrain surface compared to previous GPU-based approaches. A higher quality is achieved with respect to the grid resolution. Furthermore the combination with an error metric and ray casting enables us to render a terrain representation within a given error threshold. Hence, high quality interactive terrain rendering is guaranteed, without expensive preprocessing.Item Automatic Terrain Generation with a Sketching Interface(Václav Skala - UNION Agency, 2009) Puig-Centelles, Anna; Varley, Peter A. C.; Ripolles, Oscar; Chover, Miguel; Min, Chen; Skala, VáclavVirtual environments should offer the user a deep interactive experience with both large worlds to explore and a higher degree of perceived realism. The main goal of our work is to provide the final user with an easy-to-use accurate terrain generation application, which allows non-professional users to design their own desired terrain. In this paper we consider the creation of islands to be used in computer games. We introduce a simple terrain algorithm and we also consider its integration into a sketching application. The application will offer both a 2D and a 3D representation of the terrain, in order to simplify the interface and provide the user with more interactive feedback about the island that has been designed. Our framework offers real-time algorithms for both creating and modifying terrain features, thus improving the final results with more realism and greater customization by the user.Item Object Detection in Low Illumination Environment(Václav Skala - UNION Agency, 2009) Lee, Suk-Ho; Il Han, Seung; Gi Kang, Moon; Min, Chen; Skala, VáclavWe propose a motion detection algorithm which works well in low illumination environments. By using the level set based bimodal motion segmentation, the algorithm obtains an automatic segmentation of the motion region and the spurious regions due to the large CCD noise in low illumination environment are removed effectively. Based on a noise analysis, we will show how to obtain the required parameters automatically. Experimental results verify the stableness of the proposed algorithm in low illumination conditions.Item WEB GIS by Ajax for Analysis and Control of Environmental Data(Václav Skala - UNION Agency, 2009) Cabral, Igor P. S.; Gonçalves, Luiz Marcos G.; Xavier, João Carlos; Min, Chen; Skala, VáclavThe use of Geographic Information Systems (GIS) has becoming very important in fields where detailed and precise study of earth surface features is required. Environmental protection is such an example that requires the use of GIS tools for analysis and decision by managers and enrolled community of protected areas. In this specific field, a challenge that remains is to build a GIS that can be dynamically fed with data, allowing researchers and other agents to recover actual and up to date information. In some cases, data is acquired in several ways and come from different sources. To solve this problem, we propose a tool that includes a model for spatial data treatment on the Web, that we named System for Integrated Monitoring - SIM. The research issues involved in this tool start with the dealing of satellite images of protected areas. It is followed by acquisition and processing of different types of video and images as Small Format Aerial Images, or simply SFAI, acquired by a radio controlled helicopter, used for construction of mosaics to be fed in the GIS, and underwater geo-referenced pictures, acquired in-loco by researchers for better analyzing a given area. The SIM continues with the feeding and processing of environmental control data collected in-loco as biotic and geological variables and finishes with the presentation of all information on the Web. For this dynamic processing, we have developed tools that make MapServer more flexible and dynamic, allowing data uploading by the proper users. As example, on the top of SIM, we have developed a module that uses interpolation to aiming spatial data analysis. A very complex application that has validated our research is to feed the system with data coming from coral reef regions located in northeast of Brazil.Item Fitting freeform multi-parameter shapes to 3D data points – A case study(Václav Skala - UNION Agency, 2009) Vergeest, Joris S. M.; Song, Y.; Min, Chen; Skala, VáclavWe present an approach of geometric fitting of freeform shapes to 3D data points, where the size of the fitting problem is relatively large. The shapes studied represent ship propeller blades of dimension up to 3m, with precision requirements of few mm. Moreover, the shapes are freeform and designed using a geometric model dependent on hundreds of numerical parameters. For the ship industry it is crucial to optimally deal with the shape parameters in order to judge whether or not a particular manufactured part fits within the tolerances. We have developed a method to evaluate the shapes numerically and we report on the approach we took. The sensitivity of a deviation objective function with respect to critical design parameters could be acquired. Also some procedures for automated optimization were explored.Item A Hybrid Ambient Occlusion Technique for Dynamic Scenes(Václav Skala - UNION Agency, 2009) Knuth, Martin; Kohlhammer, Jörn; Min, Chen; Skala, VáclavIn this paper we present a hybrid technique for illuminating a dynamic scene with self shadowing. Our goal is to perform the necessary calculations with real-time or interactive frame rates. The main idea is to split up the self shadowing process into a global and a local part. This separation allows us to choose combinations of completely independent algorithmic approaches. The global part calculates the self shadowing information of the entire scene. Since it has to process the whole scene, it has a high computational cost; however, a coarse approximation can be created in a short time. In contrast the process for the local part deals with fine details, which have local impact on the scene. It only processes a relevant subset of the scene. Finally we present results based on an implementation using a GPU based self shadowing approximation combined with screen space ambient occlusion for solving the local part
