WSCG 2013: Poster Proceedings
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Item An Intelligent Flower Analyzing System for Medicinal Plants(Václav Skala - UNION Agency, 2013) Rodrigo, Ranga; Samarawickrame, Kalani; Mindya, Sheron; Skala, VáclavThe natural sciences have been transformed with the incorporation of advanced technologies, and the current technological wave of change is also revolutionizing biological science. With the wide use of herbal medicines in traditional medical systems, the demand for medicinal plants has increased enormously. Though the current trend has made the use of medicinal plants more popular, we still require better methods to distinguish between medicinal plants and plants which do not possess medicinal value. Manual methods of plant recognition rely on a plants flower information. However, these manual processes of flower recognition are not straightforward for lay persons unless expert guidance is provided. Motivated by this reasoning, an intelligent flower analyzing system has been developed to recognize medicinal plants. Various tests have been performed on 160 images taken from four types of flowers, to recognize flowers based on their colour and shape features. The experiment was carried out using Support Vector Machine (SVM) and Principal Component Analysis (PCA) methodologies respectively for colour and shape extraction. Acquiring an average of 65% recognition rate implies that the applicability PCA and SVM in the specified domain is a valuable step forward.
Item 3-D mesh-classification method based on angular histograms(Václav Skala - UNION Agency, 2013) Zawadzki, Tomasz; Nikiel, Slawomir; Ribeiro, Eraldo; Skala, VáclavMethods for analyzing of 3-D mesh topology play an important role in computer graphics problems such as segmentation, correspondence, shape recognition, editing, and animation. We present a new approach for recognition, analysis, and classification of 3-D mesh-based objects. Here, we show how histogram descriptors based on the angles between vertices can be used for grouping similar shapes and for shape classification. Our method can be customized to classify objects of varying mesh complexity (i.e., level of detail) by changing the descriptor’s resolution parameter. We demonstrate the effectiveness of our method on a 3-D object database generated using shape grammars and a hybrid morphing algorithm.Item Simultaneous Skeletonization and Topologic Decomposition for Digital Shape Reconstruction(Václav Skala - UNION Agency, 2013) Wekel, Tilman; Hellwich, Olaf; Skala, VáclavAnalyzing the structure of 2D shapes has been studied intensively in recent years. It is a key aspect in various computer vision and computer graphics applications. In this paper, a new algorithm is proposed which efficiently computes a skeleton and a corresponding decomposition of an arbitrary shape. Given the Voronoi diagram, the pruning step has linear complexity. The skeleton is a sparse 1D representation which captures the topology as well as the general structure of a shape. Considering the Voronoi diagram of the boundary vertices, the skeleton is extracted as a subset of the Voronoi edges using a simple classification scheme. A parameter allows to control the skeleton’s sensitivity to perturbations in the boundary curve. The dual Delaunay triangulation yields a topological decomposition of the shape that is consistent with the skeleton. Each part can be classified as belonging to one of three base types which have some interesting properties. The method has been successfully implemented and evaluated. The presented concepts can also be applied to manifold surfaces which is particularly useful for digital shape reconstruction as it is shown at the end of this paper.Item Efficient simulation of contacts,friction and constraints using a modified spectral projected gradient method(Václav Skala - UNION Agency, 2013) Tasora, Alessandro; Skala, VáclavThis work introduces a modified version of the Spectral Projected Gradient method that can be used for simulating dynamical systems with complex joints and frictional contacts. The proposed method is able to solve for unknown reactions in systems with large number of colliding shapes and articulated mechanisms. This method couples the ability of solving complementatity constraints, typical of fixed point iterations used in real-time applications, with the superior convergence of Krylov iterations for linear problems, hence making it attractive as a general purpose solver for both linear and non linear problems.Item Java on CUDA architecture(Václav Skala - UNION Agency, 2013) Strnad, Jan; Konfršt, Zdeněk; Skala, VáclavThis paper presents technologies, programs and Java libraries which allow usage of a CUDA capable GPU device within Java programming language. All these approaches are described with their simplified usage guide. Then, we compare performance of these methods, as well as we compare their friendliness to a programmer, documentation or their maturity. For performance tests, we used matrix multiplication and Gamma correction. We recommend to use JCuda library as currently the best available method, followed closely by JNI.Item Comparison of segmentation evaluation methods(Václav Skala - UNION Agency, 2013) Šrubař, Štěpán; Skala, VáclavQuality of segmentation depends on evaluation method we use. In case of specific images we use specific ways how to define quality. In general cases we have to use common methods. They differ in complexity as well as in quality. This article presents some of these methods and shows comparison of their quality on large image set.Item CDFC: Collision Detection Based on Fuzzy Clustering for Deformable Objects on GPU’s(Václav Skala - UNION Agency, 2013) Mainzer, David; Zachmann, Gabriel; Skala, VáclavWe present a novel Collision Detection Based on Fuzzy Clustering for Deformable Objects on GPU’s (CDFC) technique to perform collision queries between rigid and/or deformable models. Our method can handle arbitrary deformations and even discontinuous ones. With our approach, we subdivide the scene into connected but totally independent parts by fuzzy clustering, and therefore, the algorithm is especially well-suited to GPU’s. Our collision detection algorithm processes all computations without the need of a bounding volume hierarchy or any other acceleration data structure. One great advantage of this is that our method can handle the broad phase as well as the narrow phase within one single framework. We can compute inter-object and intra-object collisions of rigid and deformable objects consisting of many tens of thousands of triangles in a few milliseconds on a modern computer. We have evaluated its performance by common benchmarks. In practice, our approach is faster than earlier CPUand/ or GPU-based approaches and as fast as state-of-the-art techniques but even more scalable.Item Refined Flattening Calculation of Hot Air Baloon Shape Surface Tiles(Václav Skala - UNION Agency, 2013) Kubíček, Radek; Zemčík, Pavel; Skala, VáclavDesign of hot air balloons can benefit from computer graphics in combination with numerical methods. The balloons are usually designed using modern CAD tools where their shape is modelled in 3D space. However, the design of the 3D shape is just a beginning of a complex production process. Flattening of the designed tiles and their preparation for a fabric cut is critical for a final quality of the design. Because of a relatively small number of companies producing the hot air balloons, only a limited number of very expensive useful tools exists. This paper addresses the issues of an automatic cut design calculation based on the 3D shape and physical properties of the fabric, using advanced numerical methods combined with existing flattening algorithms.Item Structural engineering in terms of densed housing system with allowance for insolation(Václav Skala - UNION Agency, 2013) Kheyfets, Alexander L.; Skala, VáclavThe problem of a new building system within the existing residential area is considered in the article. Models and algorithms that help to calculate allowable space for a new building of a free form that won’t reduce insolation of the buildings below allowable standards, are developed. Algorithm which helps to provide necessary insolation of a new building is considered. This model is realized by means of AutoCAD with AutoLisp. Algorithm for a model as well as the example for the calculation is given in the article.Item Calibration of Depth Measurement Model for Kinect- Type 3D Vision Sensors(Václav Skala - UNION Agency, 2013) Karan, Branko; Skala, VáclavAccuracy of depth measurement with Microsoft Kinect and similar 3D vision sensors depends on variations in sensor production. Sensor reading may show significant systematic errors that can be compensated in software by using an adequate depth calibration model. This paper presents one such model and a procedure for identification of its parameters. An example calibration is given to illustrate the procedure and the attained improvements.Item Comparative Visual Aesthetics in Synesthetic Structures(Václav Skala - UNION Agency, 2013) Johnson, Adrian; Semwal, S. K.; Skala, VáclavWe describe a means of co-evolving parameters for procedural animation generation. Several experiments were completed in order to find an aesthetically pleasing animation mechanism, which could be modulated by music and have its parameters evolved over time. The selected music visualization is a set of vector fields for the purpose of moving particles whose paths create visual interest. To cause emergence of pleasing patterns in particle behaviour, several metrics were incorporated into the fitness function. To reflect the spatial characteristics of the vector fields a crossover operator was developed. The most critical aspect in creating a vector field which animates particle paths over time is that the vector field not allow the particles to become static or too tightly clustered, as either indicates the particles will no longer be circulating in interesting ways. We are interested in encouraging certain behaviours of the particles without doing so explicitly so that a local interaction approach allow for many aesthetically pleasing solutions to be reached, and rendered. This complex systems approach continues to work as interesting patterns emerge. We provide several examples with later generations creating more aesthetically complex renderings. Comparative visual aesthetics as a measure of such visual refinement is introduced. If pleasing patterns can be made implicitly with the vector fields in this specific audio-visual composition, it stands to reason that parameters for other visualizations may be evolved as well and this work serves as an argument for computer assisted comparative aesthetic refinement.Item Architectural Library. Dioscuri Temple in Agrigento(Václav Skala - UNION Agency, 2013) Inzerillo, Laura; Cardillo, Giuseppe Dalli; Skala, VáclavThis paper presents the synthesis of research about the ICT solution for cultural heritage through the innovative technology of representation and survey. One objective was to identify a method of processing data for knowledge, dissemination and preservation of the asset. Historical analysis, surveying, photogrammetry and laser scanner, the processing of survey data and modelling are all focused to the same final purpose. The methodology developed for this application framework becomes adoptable in General for Cultural Property, which become in turn the protagonists of 3D WebGIS.Item A Visualisation of the Results of a Thermoforming Process Simulation in the Plastics Industry(Václav Skala - UNION Agency, 2013) Gerža, Michal; Pokorný, Pavel; Skala, VáclavThis paper presents the SIMViewer computer program allowing users to visualise the results from the T-SIM simulation software made by Accuform in the field of plastics thermoforming. The main feature is to visualise particular thermoforming process steps of a plastic sheet in a three-dimensional space including all geometric parts of the defined model like a forming die and optional plunger. SIMViewer provides a projection of scalar quantities that characterize the thermoformed region. It is mainly focused on presenting the thickness distribution, thermoforming temperature, stress, strain and other scalars applied on the plastic sheet. This application was developed in C++ programming language, the graphical area was implemented by the OpenGL library and the user interface was created by using the MFC application framework.Item Automatic Video Generation Using Floor Segmentation from a Single 2D Image(Václav Skala - UNION Agency, 2013) Geetha, Kiran A.; Murali, S.; Skala, VáclavImage based video generation paradigms have recently emerged as an interesting problem in the field of robotics. This paper focuses on the problem of automatic video generation of indoor scenes that mainly consist of orthogonal planes. The algorithm infers frontier information directly from the images using a geometric context-based segmentation scheme that uses the natural scene structure in indoor environments. The presence of floor is a major cue for obtaining the termination point for the video generation. First, we perform floor segmentation using dilation and erosion methods. Second, compute the length of the floor using distance method which is used as the termination point for video generation. Finally, video is generated by cropping the image. Our approach needs no human interventions, hence it is fully automatic. We demonstrate the technique to a variety of applications, including virtual walk through ancient time images, in forensics and in architectural sites. The algorithm is tested on nearly 100 images obtained from different buildings, all of them are fairly different in interior decoration themes from each other.Item Volume Ray Casting quality estimation in terms of Peak Signal-to-Noise Ratio(Václav Skala - UNION Agency, 2013) Gavrilov, Nikolay; Turlapov, Vadim; Skala, VáclavIn spite of a large number of techniques aimed for improvement of Direct Volume Rendering (DVR) quality and performance proposed in the literature, there is a lack of approaches for numerical quality estimation of the images obtained by visualization of medical and scientific volumetric datasets. In this paper we propose a method to estimate sampling artifacts in DVR. Using the proposed estimation method we compare different Ray Casting algorithms to expose optimal ones in quality-performance criteria. We also propose method which combines two techniques for sampling artifacts reduction: Preintegrated DVR and Virtual Samplings method. We show that this combination overcomes both basic methods when using local shading or/and tricubic filtering in RC algorithm.Item Compressed Grids for GPU Ray Tracing of Large Models(Václav Skala - UNION Agency, 2013) Costa, Vasco; Pereira, João M.; Jorge, Joaquim A.; Skala, VáclavRay tracing on GPUs is an area of ongoing research. GPUs are well suited for this parallel rendering algorithm. GPU computing devices typically have characteristics which make them quite different from CPUs: increased data parallelism, increased memory bandwidth, smaller caches, lower memory capacity. Presently it is difficult to visualize large scenes with tens of millions of triangles in these memory constrained platforms. In this paper we present a compressed grid data structure, capable of state of the art rendering performance, using up to 6 less memory than conventional grid storage schemes. The compressed grid is built and traversed on the GPU.Item GPU-Optimized Bi-Directional Path Tracing(Václav Skala - UNION Agency, 2013) Bogolepov, Denis; Ulyanov, Danila; Sopin, Dmitry; Turlapov, Vadim; Skala, VáclavIn this paper we present a light-weight modification of bi-directional path tracing algorithm that is optimized for massively parallel architectures with limited memory, like GPU. The amount of computations performed by the algorithm is still comparable to unidirectional path tracing. Though modified algorithm preserves some benefits of general bi-directional path tracing and handles indirect illumination and caustics quite efficiently.Item Light Field Retrieval In Compressed Domain(Václav Skala - UNION Agency, 2013) Bellhallouche, Lakhdar; Belloulata, Kamel; Kpalma, Kidiyo; Skala, VáclavIn this paper, we present a novel approach for light field retrieval in the transformed domain. The light field data set is characterized with low wavelet transform coefficients. Our algorithm first applies a wavelet transform on 20 key images of the light field structure. The low wavelet transform coefficients are then quadtree decomposed, into a set of homogeneous blocks. Each set of homogeneous blocks represent an object in the considered image. We use texture and color features to characterize the object image; the similarity between two images is measured by matching their histograms. The experimental results and comparisons show the performance of the proposed technique.
