Volume 11, number 1-3 (2003)
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Item New Fingerprint Image Enhancement Using Directional Filter Bank(UNION Agency – Science Press, 2003) Oh, Sang Keun; Lee, Joon Jae; Park, Chul Hyun; Kim, Bum Soo; Park, Kil Houm; Skala, VáclavThis paper describes a new method of directional filter-based analysis for fingerprint enhancement. Fingerprint images can be represented by a directional field of regular structure of ridge patterns. The dominant directional component of ridge plays a very important role in the pre-processing steps of fingerprint image analysis such as ridge's linking and noise removal for minutiae extraction. A directional filter bank analyzes an input image into directional subband images and synthesizes them to the perfectly reconstructed image. In this paper, a new fingerprint enhancement algorithm based on a directional filter bank is proposed. The algorithm decomposes a fingerprint image into directional subband images in the analysis stage, processes the subband images in the processing stage, and reconstructs them as the enhanced image in the synthesis stage. The experiment results show that the proposed method reduces the influence of noise on the ridges and valleys, enhances the ridge’s moving shape, and preserves the spatial characteristics at minutiae and singular points.
Item Edge-enhancement: an algorithm for real-time(UNION Agency – Science Press, 2003) Nienhaus, M.; Doellner, Juergen; Skala, VáclavIn this paper, we propose an algorithm for enhancing edges of real-time non-photorealistic renderings. It is based on the edge map, a 2D texture that encodes visually important edges of 3D scene objects, and includes silhouette edges, border edges, and crease edges. The edge map allows us to derive and augment a wide range of nonphotorealistic rendering styles. Furthermore, the algorithm is designed to be orthogonal to complementary realtime rendering techniques. The implementation is based on multipass rendering: First, we extract geometrical properties of 3D scene objects generating image-space data similar to G-buffers. Next, we extract discontinuities in the image-space data using common graphics hardware to emulate image-processing operations. In subsequent rendering passes, the algorithm applies texture mapping to combine the edge map with 3D scene objects.Item Interactive animation of cloth including self collision(UNION Agency – Science Press, 2003) Fuhrmann, Arnulph; Groß, Clemens; Luckas, Volker; Skala, VáclavWe describe a system for interactive animation of cloth, which can be used in e-commerce applications, games or even in virtual prototyping systems. In order not to restrict the shape of the cloth we use a triangulated mesh, which serves as basis of a mass-spring system. For the animation of the particles internal and external forces are considered. Since cloth is a very rigid material when stretched, extremely large forces occur in such a system. Several methods have been described in the recent years to solve the underlying differential equations efficiently. We describe an algorithm which replaces the internal cloth forces by several constraints and therefore can easily take large time steps. These constraints can be parameterized to generate different behavior of the simulated cloth. Furthermore we provide an algorithm for an efficient avoidance of self collisions. For these reasons very plausible animations of cloth at interactive rates are possible with our system.Item Blob-representation of multidimensional objects and surfaces(UNION Agency – Science Press, 2003) Herman, Gabor T.; Garduño, Edgar; Skala, VáclavItem Welcome to the 11-th international conference in Central Europe on computer graphics, visualization and computer vision 2003!(UNION Agency – Science Press, 2003) Bresenham, J. E.; Skala, VáclavItem Large model visualization: techniques and applications(UNION Agency – Science Press, 2003) Bartz, Dirk; Skala, VáclavThe visual representation of complex data has always been a major motivation for computer graphics. However, there have always been computer graphics scenes which were too complex to be rendered within a reasonable time limit, or even too complex to be rendered at all with the available resources. Nevertheless, computer graphics has become one of the primary tools used for the interpretation of data from engineering or science. By the end of the eighties, the application of computer graphics methods for the visual interpretation of scientific data became a research field on its own and was called Scientific Visualization. By now, it is almost unthinkable to understand data, which is generated by simulations or is measured, without any graphics or visualization technology. The technology used ranges from simple plot drawings, via direct volume rendering techniques to provide semi-transparent view through a dataset, to illuminated streamlines, and line integral convolutions to visualize the flow of particles through multi-dimensional and multi-variate data.Item Complex water effects at interactive frame rates(UNION Agency – Science Press, 2003) Loviscach, Jörn; Skala, VáclavDue to the complexity of the effects, it is difficult to achieve photorealism and physically correct motion in interactive 3-D water simulations. We present a simulation and visualization method which goes a long way towards physical reality, e. g. by producing Kelvin ship waves and displaying images of real caustics on the water surface. Using efficient approximations and employing the specialized 3-D and CPU features of modern PCs, this simulation runs at rates of several frames per second. Part of this solution is the emulation of a hardware accumulation buffer on consumer 3-D graphics cards with the help of texture shaders.Item Generating nonverbal indicators of deception in virtual reality training(UNION Agency – Science Press, 2003) McKenzie, Frederic; Scerbo, Mark; Catanzaro, Jean; Skala, VáclavOld Dominion University (ODU) has been performing research in the area of training using virtual environments. The research involves both computer controlled agents and human participants taking part in a peacekeeping scenario whereby various skills-based tasks are trained and evaluated in a virtual environment. The scenario used is a checkpoint operation in a typical third world urban area. The trainee is presented with innocuous encounters until a slightly noticeable but highly important change surfaces and the trainee must react in an appropriate fashion or risk injury to himself or his teammate. Although the tasks are mainly skill-based, many are closely related to a judgment that the trainee must make. In fact, judgment-based tasks are becoming prevalent and are also far more difficult to train and not well understood. Of interest is an understanding of these additional constraints encountered that illicit emotional response in judgment-based military scenarios. This paper describes ongoing research in creating affective component behaviors used to convey cues for anger, nervousness, and deception in Operations Other than War (OOTW) training.Item Remote display of large raster images using JPEG2000 and the rectangular FishEye-View(UNION Agency – Science Press, 2003) Rosenbaum, René; Taubman, David S.; Skala, VáclavIn mobile environments, the size of large raster images often exceeds the display area on small output devices. The rectangular Fish Eye-View as a Focus & Context technique can be used to provide an interactive view of the image without zooming and panning. This paper presents the application of JPEG2000 for the demand-driven transmission of image data optimized for this display technique. The proposed method is fully compliant to the JPEG2000 standard and enhances its static concept for regions of interest to be fully dynamic. Due to limited processing power at client side almost all calculations belonging to the dynamic RoI-coding are executed at server side.Item A global signal propagation technique for the modeling of plants(UNION Agency – Science Press, 2003) Velha, Pedro Luiz Eira; Fabris, Antonio Elias; Skala, VáclavThis paper introduces a new technique for modeling signal and nutrient propagation in plant models to counteract the main disadvantages of current methods: the difficulty of setting the velocity of the propagation and the complexity of models with many signals. This technique uses implicit parameters and global propagation functions, offering a better control over the velocity of propagation, making the modeling of many independent signals an easy task, and keeping the model simple and objective. Furthermore, our approach is easy to be aggregated into existing models and makes the modeling of signal and nutrient propagation a more intuitive task.Item Interactive rendering technique for realistic oriental painting(UNION Agency – Science Press, 2003) Yu, Young Jung; Lee, Do Hoon; Lee, Young Bock; Cho, Hwan Gue; Skala, VáclavInteractive and realistic rendering of various effects which are appeared in the real world paintings can be used for several applications such as animation or education. For Western paintings, watercolor or oil paintings have been main subjects for representation and model-based approaches have been researched. In case of Oriental paintings, numerous studies have focused on model-based approaches. In this paper, a new model-based approach for Oriental paintings is described. To represent the diffusion effects, we propose local equilibrium model(LEM) which is a method to calculate the movement of water and ink effectively. With LEM, the diffusion of water and ink can be processed interactively and realistic diffusion effects can be generated. In addition, we propose a layer model. With this layer model, overlapped strokes can be well represented. Conclusively, we show several results of Oriental paintings drawn with proposed methods.Item Cylindrical relief texture mapping(UNION Agency – Science Press, 2003) El Helw, Mohamed A.; Yang, Guang-Zhong; Skala, VáclavThis paper describes a new Image Based Rendering technique aimed at increasing the realism of textured cylindrical surfaces by adding 3D details and enhancing the depth conceived by the viewer. Cylindrical relief texture mapping extends the existing work on planar relief textures by using cylinders as warp surfaces. After mapping the planar relief texture to a reference cylinder, cylindrical warping equations are used to generate an intermediate image for texture mapping the reference cylinder and introducing motion parallax. The strength of the technique is demonstrated by the visual realism provided, with examples showing how the proposed method can be used for generating depth enhanced panoramas and improved endoscopic simulations.Item Real-time terrain rendering using smooth hardware optimized level of detail(UNION Agency – Science Press, 2003) Larsen, Bent Dalgaard; Christensen, Niels Jørgen; Skala, VáclavWe present a method for real-time level of detail reduction that is able to display high-complexity polygonal surface data. A compact and efficient regular grid representation is used. The method is optimized for modern, low-end consumer 3D graphics cards. We avoid sudden changes of the geometry - also known as 'popping', when reducing the geometry by exploiting the low-level hardware programmability in order to maintain interactive framerates. Terrain models are repolygonized in order to minimizing the visible error. Furthermore, the method minimizes CPU usage during rendering and requires minimal pre-processing. We believe that this is the first time that a smooth level of detail has been implemented in commodity hardware.Item Rendering large (volume) datasets: a new parallel visualization system(UNION Agency – Science Press, 2003) Schneider, Sascha; May, Thorsten; Schmidt, Michael; Skala, VáclavIn this paper we describe a basis for a system that is able to compute actual scientific and realistic visualization methods in parallel. It is capable to integrate easily in modern VR renderers like for example Open Inventor [SGIa], Coin [Coi] and OpenSG [Vos02]. Our approach is advantageous for processing large datasets which usually are the result of physically based simulation algorithms and programs. Using our techniques it is even more feasible to manage similar visualization problems for other large amounts of data (e.g. medicinal CT-scans or large geometries) in the context of displaying interactively.Item Progressive compression of visibility data for view-dependent multiresolution meshes(UNION Agency – Science Press, 2003) Zach, Christopher; Karner, Konrad; Skala, VáclavIn this paper we present a lossless and optionally lossy compression method for precomputed visibility data for view-dependent multiresolution meshes, which supports out-of-core rendering and progressive transmission through slow connections. Our approach has the feature, that visibility information can be stored directly in the nodes of the multiresolution structure and only necessary parts of visibility data need to be transmitted. Nevertheless our lossless compression method performs better than wellknown general purpose solid compressors which inhibit selective access of required data. Even higher compression can be achieved when lossy preprocessing is performed. We evaluate our method on several arti cial and real datasets.Item Efficient cellular automata for 2D / 3D free-form modeling(UNION Agency – Science Press, 2003) Druon, S.; Crosnier, A.; Brigandat, L.; Skala, VáclavThis paper presents an approach for efficiently simulating highly deformable 2D substances undergoing viscoplastic deformations in real time. The user deals with objects in the same way as clay works. Based on the work of Y. Takai and H. Arata, we suggest a new approach for the computation of repartition rules. We use a discrete 2D space in which each pixel is given a certain amount of clay at the intialisation of the system. The user’s tool only moves some clay from a pixel to another, creating an overload. The repartition of this overload amoung the neighbours is then made according to the laws of plastic deformation thanks to a cellular automaton.Item Compression of arbitrary triangle meshes with attributes for selective refinement(UNION Agency – Science Press, 2003) Grabner, Markus; Skala, VáclavWe present a method for compact encoding of attributes such as normal vectors defined on a triangle mesh of arbitrary topology suitable in the context of viewdependent simplification. It is based on the recently introduced CAME data structure (Compressed Adaptive Multiresolution Encoding). In accordance with the vertex hierarchy defined by mesh simplification, we define an attribute hierarchy to track attribute values within the multiresolution representation. It is shown that the corner subgraph describing the relations between attributes in a mesh simplification step can be efficiently en coded if attributes are properly ordered.Item Melting objects(UNION Agency – Science Press, 2003) Jones, M. W.; Skala, VáclavThis paper describes a technique for producing realistic animations of melting objects. The work presented here introduces a method that accurately models both thermal flow and the latent heat during the phase change. The mechanism for energy transfer to the model is via both boundary conditions and radiation. Emphasis is made on accurately modelling the solid object and the method is particularly suited to rigid solids with complex surface geometry. The underlying objects are constructed using Volume Graphics modelling techniques (specifically voxelization), and a numerical simulation computes the time-dependent heat flow throughout the object. A technique for computing the phase transition is given, and details for rendering the melting objects are provided. The melting is controlled by material parameters, such as specific heat capacity, thermal conductivity, latent heat and temperature. Examples are given of melting ice and a plastic man.Item Optimal curve fitting to digital data(UNION Agency – Science Press, 2003) Sarfraz, Muhammad; Skala, VáclavAn optimal curve fitting technique has been developed which is meant to automatically provide a fit to any ordered digital data in plane. A more flexible class of rational cubic functions is the basis of this technique. This class of functions involves two control parameters, which help to produce optimal curve fit. The curve technique has used various ideas for curve design. These ideas include end-point interpolation, intermediate point interpolation, detection of characteristic points, and parameterization. The final shape is achieved by stitching the generalized Bézier cubic pieces with an ideally acceptable smoothness.Item A simple but effective algorithm to model the competition of virtual plants for light and space(UNION Agency – Science Press, 2003) Van Haevre, William; Bekaert, Philippe; Skala, VáclavWe present a simple but effective algorithm to simulate plant growth in a realistic way, taking into account illumination, spatial occupancy and the nearby presence of other plants. The basic idea of our algorithm is to simulate light flow during all stages of plant development, by tracing virtual photons emitted by light sources in the same way as it is done in many global illumination algorithms. We augment the L-system, modelling plant growth, with a mechanism for determining predominant illumination directions by analysing the distribution of the direction of incidence of photons hitting plant parts. Based on photomorphogenesis principles found in literature, the same photons are used to “discourage” plants from growing into each other by penalizing the contribution of photons reflected of other plants. At this time, our algorithm is implemented using the very simplest solutions at all stages. Nevertheless, first experiments show that the approach is promising. In future work, the algorithm proposed here will be refined considerably in various ways.
