WSCG '2011: Full Papers Proceedings
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Item Photo Quality Assessment based on a Focusing Map to Consider Shallow Depth of Field(Václav Skala - UNION Agency, 2011) Ryu, Dong-Sung; Park, Sun-Young; Cho, Hwan-Gue; Baranoski, Gladimir; Skala, VáclavProliferation and advances in digital cameras encourage people to take many photos. However, the number of photos that people can access is increasing exponentially. Good quality photo selection is becoming burdensome. In this paper, we propose a novel method to evaluate photo quality considering DoF (Depth of Field) based on a focusing map. The focusing map is a form of saliency map classified into four levels based on the spatial distribution of Canny edges. We implemented it in a CUDA environment to improve the speed of focusing map generation. In order to evaluate our method, we tested our feature on the four classified 206 photos; then, we compare our method to a photo set manually classified by a user. The proposed measure efficiently assesses the photos with DoF. Especially, the expert group who used DSLR camera agreed that our photo assessment measure is useful.
Item Multi-material Volume Segmentation for Isosurfacing Using Overlapped Label Propagation(Václav Skala - UNION Agency, 2011) Niizaka, Takuma; Ohtake, Yutaka; Michikawa, Takashi; Suzuki, Hiromasa; Baranoski, Gladimir; Skala, VáclavThis paper proposes a simple and efficient method for segmenting multi-material volumes. Unlike standard image segmentation techniques, this approach aims to extract accurate isosurfaces representing the boundary surfaces between different materials. The segmented volumes obtained in this way meet the requirements of the topological correctness and geometrical accuracy for isosurfacing. The approach involves three steps: first, voxels far from the boundary surfaces are labeled; then, the labels are propagated with overlapping to ascertain which materials meet near the boundary surfaces; finally, an appropriate material is selected from among the multiple labels assigned to a voxel with adaptive thresholding. Since the method consists of iterative local operations, it is easy to parallelize for fast computation. The efficiency of the technique is demonstrated here using CT scanned objects for complex shapes.Item Virtual LEGO Modelling on Multi-Touch Surfaces(Václav Skala - UNION Agency, 2011) Mendes, Daniel; Ferreira, Alfredo; Baranoski, Gladimir; Skala, VáclavConstruction of LEGO models is a popular hobby, not only among children and young teenagers, but also for adults of all ages. Following the technological evolution and the integration of computers into the everyday life, several applications for virtual LEGO modelling have been created. However, these applications generally have interfaces based on windows, icons, menus and pointing devices, the so-called WIMP interfaces, thus being unnatural and hard-to-use for many users. Taking advantage of new trends in of interaction paradigms we developed an innovative solution for virtual LEGO modelling using a horizontal multi-touch surface. To achieve better results, we selected the most common virtual LEGO applications and performed a comparative study, identifying advantages and disadvantages of each one. In this paper we briefly present that study and describe the application developed upon it.Item Interactive Exploration and Analysis of Pathlines in Flow Data(Václav Skala - UNION Agency, 2011) Lež, Alan; Zajic, Andreas; Matković, Krešimir; Pobitzer, Armin; Mayer, Michael; Hauser, Helwig; Baranoski, Gladimir; Skala, VáclavThe rapid development of large-scale scientific computing nowadays allows to inherently respect the unsteady character of natural phenomena in computational flow simulation. With this new trend to more regularly consider time-dependent flow scenarios, an according new need for advanced exploration and analysis solutions emerges. In this paper, we now present three new concepts in pathline analysis which further improve the abilities of analysis: a multi-step analysis which helps to save time and space needed for computation, direct pathline brushing, and the use of pre-configured view arrangements. We have found that a clever combination of these three concepts with already existing methods creates a very powerful tool for pathline analysis. A solution that follows the concept of coordinated multiple views (CMV) with iterative composite brushing enables a quick information drill-down. We illustrate the usefulness of this approach in the context of an example from the automotive industry.Item Snake-based Technique for Automated Coronal Loop Segmentation(Václav Skala - UNION Agency, 2011) Lee, Jong Kwan; Tang, Woon Khang; Baranoski, Gladimir; Skala, VáclavA new approach to automatically segment the solar coronal loop structures from intensity images of the Sun’s corona is described. The approach is based on the active contour models (snakes) and exploits the Gaussian-like shape of the coronal loop cross-sectional intensity profile to refine the snake’s position. The approach utilizes the principal component analysis to automatically initialize the snake’s position. It then uses a greedy minimization method to attract the snake toward the center of coronal loop structures in each image. Its effectiveness is evaluated through experiments on synthetic and real images.Item ARGreenet and BasicGreenet: Two mobile games for learning how to recycle(Václav Skala - UNION Agency, 2011) Juan M., Carmen; Furió, David; Alem, Leila; Ashworth, Peta; Cano, Juan; Baranoski, Gladimir; Skala, VáclavIn this paper, a new Augmented Reality (AR) mobile phone game ‘ARGreenet’ is presented. The game aims to raise individuals’ awareness of the importance of recycling and teaching participants how to do it. In this research, the ‘ARGreenet’ is compared with a similar ‘Basic’ mobile phone game for recycling. Thirty eight children aged from 8 to 13 years of age participated in this study. To quantify aspects of the utility and effectiveness of the games, the children answered questionnaires both before and after using each game. Aspects examined included the level of engagement and fun of each game, the ease of use and perceived value of each game, and the perceived learning about recycling. We report a positive change in intended behavior with both games. The results suggest that playing both games is likely to have a positive influence in changing participants’ recycling behaviour. These preliminary results also suggest that the mobile phone is potentially a good platform for not only learning about recycling but also influencing people to change their behaviour. A majority of the participants expressed a preference for ARGreenet game. They perceived it as easy to use and more engaging and fun than the BasicGreenet game.Item Image-based Animation(Václav Skala - UNION Agency, 2011) Choudhury, Biswarup; Raghothaman, Ambareesha; Chandran, Sharat; Baranoski, Gladimir; Skala, VáclavAnimation has evolved over the years – from the early days of 2D animation to the present technology of using GPU-based shader programs for providing complex, photorealistic lighting. One thing has, however, remained constant – a geometrical model has been considered essential in computer animation. In this paper, we propose an alternative. An image-based framework is presented for creating arbitrary motions of an object using only captured images of the object; no geometry of the object or the environment is provided by the user. Photorealism is an immediate side effect as a consequence. Specifically we preprocess a set of images of a static object under a set of carefully chosen lighting configurations. Now given an arbitrary environment in the form of images again, and any arbitrary three-dimensional path that the object is desired to move, our algorithm creates a motion sequence of the object-realistically composed in the new environment.Item Performance Considerations When Using a Dedicated Ray Traversal Engine(Václav Skala - UNION Agency, 2011) Davidovič, Tomáš; Maršálek, Lukáš; Slusallek, Philipp; Baranoski, Gladimir; Skala, VáclavIn the recent years we have witnessed massive boost to hardware graphics accelerators (graphics cards), not only in the raw performance, but also in their programmability, introducing the concept of GPGPU. However, despite this, the current architectures still favor feed-forward algorithms over recursive ones. While shading is, in this sense, a feed-forward algorithm, ray tracing, and specifically ray traversal, is a recursive rather than feed-forward algorithm. Adding a dedicated hardware ray traversal engine should therefore prove to be an interesting option. Also, with dedicated hardware, we can perform many optimizations on arithmetic units due to their fixed interaction. This can reduce the area well below a simple sum of areas of the individual units. In this paper we offer for consideration analysis of memory requirements for combination of a dedicated hardware ray traversal and intersection engine with highly parallel general purpose processor used for shading. We show results and requirements of such a combination on scenes of moderate complexity, with regard to speed, bandwidth and latency.Item Compact Rectilinear Grids for the Ray Tracing of Irregular Scenes(Václav Skala - UNION Agency, 2011) Costa, Vasco; Madeiras Pereira, João; Baranoski, Gladimir; Skala, VáclavRegular grid spatial subdivision is frequently used for fast ray tracing of scanned models. Scanned models feature regular sized primitives, with a regular spatial distribution. Grids have worse performance, than other subdivision techniques, for irregular models without these characteristics. We propose a method to improve the performance of grids for rendering irregular scenes by allowing the individual placement of grid split planes: the rectilinear grid. We describe how to construct and traverse a rectilinear grid. To exploit cache memory in modern processors compression is used for the split plane and grid cell data. We demonstrate in a series of tests that the method has faster ray tracing rendering performance than a compressed regular grid of similar dimensions.Item GPU-assisted 3D Pose Estimation under realistic illumination(Václav Skala - UNION Agency, 2011) Braun, Anne; Müller, Stefan; Baranoski, Gladimir; Skala, VáclavThis paper describes an approach which combines computer vision methods with techniques from the area of computer graphics. This method which is called analysis-by-synthesis explicitly seeks for consideration of environmental information in order to improve the resulting estimation of the 3D camera pose. In this paper, two different kinds of pose estimation will be presented. The first approach uses intensity-based methods and the second one is a feature point-based approach. The described approaches are based on a GPU-assisted rendering considering the real world illumination. These real world lighting conditions are captured using a HDR sampling technique. The results of this GPU-assisted approach are that both methods, the intensity-based as well as the feature point-based method, achieve better results in terms of a more robust and stable 3D camera pose under consideration of the real environmental information.Item New path planning method for computation of constrained dynamic channels in proteins(Václav Skala - UNION Agency, 2011) Beneš, Petr; Strnad, Ondřej; Sochor, Jiří; Baranoski, Gladimir; Skala, VáclavCollision-free paths in the geometric model of a protein molecule reveal various dependencies between the structure of the molecule and its function. The paths which connect a biochemically important part of the protein molecule with the surface of the molecule can serve as egression or access paths for small molecules which react in the active site. The geometric method introduced in this paper is designed to compute such paths in the dynamic models of protein molecules. The paths have to satisfy additional constraints such as valid flow of time which allows us to distinguish between access and egression paths, minimum width and others. Possibly, the method may be used not only for protein molecules but also for similar environments with high density of spherical obstacles. The method was tested on real protein data and the results indicate that if there is a path present, it is detected by our method.
