WSCG ’2007: Posters proceedings
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Item Finding direction of intersection curve in critical cases of surface-surface intersection(Václav Skala – UNION Agency, 2007) Oh, Min-jae; Hur, Seok; Kim, Tae-wan; Skala, VáclavDetermining the topology of intersection curves is one of the important issues of surface-surface intersection problem used in Computer Aided Geometric Design and Computer Graphics. To compute the intersection curves, we first need to determine the topology of the curves. Thomas A. Grandine[Gr97] presented an algorithm to determine topology using partial derivatives of surface intersection equations. When the two surfaces meet tangentially, the differential values of the parameters of the surfaces are not determined in the intersection equations. These cases are called critical cases. In [Ye99] a method of finding the values of the differentials is presented for the case of the contact of order 1. We present general methods for the case of the contact of higher order ≥ 1 using perturbation method. With these results, we can decide starting or ending of the critical boundary point.
Item Duct tracking in 3D medical data(Václav Skala – UNION Agency, 2007) Petříček, Martin; Pelikán, Josef; Horák, Martin; Skala, VáclavImplementing duct tracking of bronchi and blood vessels in 3D medical data can significantly help in examining these body structures and reduce time needed for correct diagnosis. Nature of the problem involved may require some operator interaction when selecting duct branches of interest or correcting possible mistakes in duct path segmentation. Noise, badly discernible duct walls, branching or extreme duct curvatures, that can be found in computer tomography data, make the segmentation challenging. There are more ways to display segmented ducts, as overlay over original data or unrolled to planar tube, allowing easier measurements of length, width or observation of tube anomalies.Item Design patterns for multithreaded software pipelines in real time applications(Václav Skala – UNION Agency, 2007) Preuss, Stefan; Schmitt, Alfred A.; Skala, VáclavThis paper presents design patterns that will help in the task of parallelizing graphical real time algorithms, according to the example of a visual real time 3D reconstruction algorithm. These algorithms can often be designed as a dataflow graph, so they can be coarsely granular parallelized in a pipeline pattern. With these patterns, the design process of the parallelization is detached from the design of the graphical algorithm. The advantages and drawbacks of these patterns are discussed with regard to speed, but also to handling and errorproneness and the demanded robustness of real time applications, due to the varying workload of the different steps or data loss or obsoleteness during processing.Item Implementation of NURBS curve derivatives in engineering practice(Václav Skala – UNION Agency, 2007) Procházková, Jana; Procházka, David; Skala, VáclavDerivatives are a very important tool of computations in an engineering practice on the graphics structures. B-Spline functions are defined recursively, so the direct computation is very difficult. In this article new direct proof of the formula used for simpler direct computation is shown. The paper also presents own method of programming derivatives of NURBS curves by means of the proven formula which is implemented in German engineering software RFEM 3D.Item Computer composition of transformed classical surfaces as the ways and means for constructing visual models of realistic objects (New software application “ArtMathGraph”)(Václav Skala – UNION Agency, 2007) Rachkovskaya, Galina S.; Kharabayev, Yuriy N.; Rachkovskaya, Natalya S.; Skala, VáclavThe new software application “ArtMathGraph” (AMG) is developed for constructing a visual representation of predetermined complicated geometrical forms as visual models of realistic objects, including objects of Nature. This application is based on the methods of Analytical Geometry and Computer Graphics only. The AMG application includes two basic methodical parts: 1 - the analytical modeling and computer visualization of multiple different sets of new mathematical transformed surfaces as components for a consequential computer superposition of these surfaces; 2 - interactive visual modeling of predetermined geometrical forms by using the computer superposition of constructed mathematical transformed surfaces. By experience, consecutive use of all means of the AMG application allows obtaining various compositions of visual images of realistic objects (Figures 1, 2).Item Controlling 3D characters by hand motion(Václav Skala – UNION Agency, 2007) Saitoh, Misae; Miyamoto, Kenji; Skala, VáclavA method to control motions of complex 3D characters interactively using hand movements is described. After capturing actor's motion, by motion capture systems transfer it as it is to 3D character’s motion. Motion capture fails, however, when the target character is of shape far different from that of the actor captured. This article proposes manipulating 3D character by controllable parameters extracted from monocular image of the actor's hand without reconstructing its posture. Using Digital Puppet System which implements this method allows a user to easily manipulate characters of various shapes ranging from a human-type robot to a mollusk with largescale set of joints. By extracting as many controllable parameters as possible, our method makes maximal use of available information which is not necessarily enough for posture reconstruction.Item A curvilinear cutting tool for the analysis of oceanography data(Václav Skala – UNION Agency, 2007) da Silva, Nathalie Rey; Manssour, Isabel Harb; Skala, VáclavThe use of new technologies for the ocean data acquisition produced a considerable increase of information. Thus, scientific visualization tools become essential to aid the oceanographers during the analysis and interpretation of ocean behavior. The main goal of this paper is to present the design and development of a set of tools for 3D visualization of simulated oceanic data, including a new approach for the selection of regions of interest using a curvilinear clipping tool. The implementation is based on a study about the tasks developed by the oceanographers of the Research Center of Petrobras.Item A method for generating developments using decomposition into the meaningful components of 3D polygon models(Václav Skala – UNION Agency, 2007) Nishio, K.; Iwaizumi, T.; Nakamura, N.; Kobori, K.; Skala, VáclavWe propose a method for generating developments from 3D polygon models automatically. The conventional method generates the developments whose components are not interfering each together, by using collision detection between all polygons. However, for the model which consists of a large number of polygons, it is necessary to decompose the development into several parts manually. Therefore it is difficult to generate the development which is easy to be assembled. Our method decomposes the polygon model into meaningful components such as arms, legs, and so on, and develops them. This makes it easy to understand which parts should be glued together, and handcraft bending or folding the developments when a user assembles the paper craft.Item An improved BRDF method for 3D textile simulation(Václav Skala – UNION Agency, 2007) Li, Bei-Bei; Zhao, Zhi-Hong; Geng, Zhao-Feng; Skala, VáclavThere are some methods suggested by researchers were used to simulate one or two characteristics of textile in the past few years. With 3D geometry models, most of these methods are somewhat complex, and it is difficult to simulate fabric attributes. This paper represents a method for textile simulation based on improved BRDF illumination models. As one simple type of BRDF model, Phong illumination model can be used to simulate fabric 3D geometry model. The more complex BRDF illumination model may be used to simulate fabric 3D structure. The pixel color values, derived from simulating fabric 3D structure, is taken as the parameters to be entered into Phong illumination model. And thus both the fabric 3D geometry model and structure can be achieved, based on which the textile can be simulated successfully and obtain a perfect display effect.Item Combining the interaction styles to display complex data in decision-making system(Václav Skala – UNION Agency, 2007) Moroz Lapin, Kristina; Rakovskaja, Olga; Skala, VáclavAnalyzing the large amount of complex data is becoming increasingly difficult. This problem impels the interface designers to search for the methods to display such data in a usable way. Combining human computer interaction styles with information visualization techniques provides some solutions. Displaying the relevant data in appropriate level of abstraction can be a good interface design solution. The most important data is focused when the others are accessible but presented in a higher level of abstraction. Presenting the same data in a different manner when multiple views are used also can give good results. The combination of techniques and styles benefits the analyst’ decision-making process.Item Experiments with volumetric data interpolation(Václav Skala – UNION Agency, 2007) Kolcun, Alexej; Pravda, Daniel; Skala, VáclavMarching Cubes and Marching Tetrahedra methods expect data in the nodes of used grid. However, very often we need the isosurface extraction from data defined in the cells of the grid. In this paper we compare the criteria for interpolation values from cells to vertices of the structured grid.Item Development of virtual goldfish scooping using haptic device(Václav Skala – UNION Agency, 2007) Kobori, Ken-ichi; Hori, Takanori; Nakamura, Norihiro; Nishio, Koji; Skala, VáclavGoldfish scooping is one of the traditional Japanese play. In general, people scoop goldfish in a shallow water tank using a fragile water-thin dipper. In this paper, we describe virtual goldfish scooping system using haptic device and stereoscopic display.Item Topology maps for anisotropic shading(Václav Skala – UNION Agency, 2007) Hast, Anders; Skala, VáclavThere are a number of materials, like cloth, hair and brushed metal that exhibit anisotropic reflectance properties. Several illumination models have been proposed for shading of such materials. The model by Poulin and Fournier describes how hair, silk and material which can be modeled by parallel cylinders, can be rendered. It has been proposed recently how the topology for this model can vary over the surface as would be the case for many surfaces like spheres and toruses. In this paper it is described how the shading can be visually enhanced by using a map for the topology. The result will be a much more visually pleasing rendering.Item Accelerated pan and zoom for ray traced animation(Václav Skala – UNION Agency, 2007) Gage, Phil G.; Semwal, Sudhanhu K.; Skala, VáclavRay tracing generates realistic images but is computationally intensive, especially when generating animation sequences. Many techniques have been developed, including exploitation of temporal coherence between successive frames to accelerate animation. This paper presents an efficient pan and zoom algorithm called the Panimation and RSVP algorithm, respectively. This new pan and zoom algorithm integrates the object animation acceleration technique of Jevans with the new pan and zoom algorithms and shows an order of magnitude performance improvement. Short animation sequences are presented to show our results.Item Customizable tool for complex systems visualization(Václav Skala – UNION Agency, 2007) Dodo, Meva; Torguet, Patrice; Sibilla, Michelle; Jessel, Jean Pierre; Skala, VáclavThe last generation of tools used for complex systems monitoring are based on 3D visualization. No doubt, they have allowed to make several improvements but the large amount of dynamical information gathered from heterogeneous environments and the growth of management protocols still make monitoring tasks an interesting research topic. A set of techniques is presented here to manage any complex system by offering a customizable 3D visualization tool associated with a standard information model, which enables to manage environments, devices and applications uniformly regardless of industry and vendor. The aim of this work is to allow tools for any complex system management and monitoring, but we have chosen clusters/grids of networked computers as a first domain of study.
