EG 2015 - Short Papers

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https://diglib.eg.org/handle/10.2312/12087

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Browsing EG 2015 - Short Papers by Subject "I.3.3 [Computer Graphics]"

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    3D Architectural Modeling: Efficient RANSAC for n-gonal Primitive Fitting
    (The Eurographics Association, 2015) Abdullah, Ahsan; Bajwa, Reema; Gilani, Syed Rizwan; Agha, Zuha; Boor, Saeed Boor; Taj, Murtaza; Khan, Sohaib Ahmed; B. Bickel and T. Ritschel
    We present a modeling approach to automatically fit 3D primitives to point clouds in order to generate a CAD like model. For detailed modeling we propose a new n-gonal 3D primitive and a novel RANSAC based fitting approach. Non-planar surfaces are modeled through surface of revolution with B-spline profiles. We first reduce the dimension by projecting the 3D data onto a 2D plane. Primitive fitting algorithm is then applied in this 2D space. Our approach compares favorably both with manually and automatically generated models. Not only is it much more time efficient than manual modeling, but it also gives significantly better output than state-of-the-art automatic methods. Since the focal technique of our approach is the fitting of detailed primitives, our results are ideal in the domain of architecture and preservation of heritage.
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    Content-Aware Projection for Tiny Planets
    (The Eurographics Association, 2015) Brown, Matthew; B. Bickel and T. Ritschel
    Tiny Planets visualise the world looking down at the ground, with physically unrealisable projections that curve the ground plane to look like small worlds. Whilst certain geometries, such as Stereographic, are known to give good Tiny Planet visualisations, the best projection to use depends on the image content. In this work we define a family of Tiny Planet projections that includes several commonly used projection types, but allows for datadependent adaptation to best present the image content to the viewer.We show how to select optimal content-aware projections from this set, minimising distortions from conformality whilst closing gaps and emphasising salient areas in the scene.
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    Interactive HDR Environment Map Capturing on Mobile Devices
    (The Eurographics Association, 2015) Kán, Peter; B. Bickel and T. Ritschel
    Real world illumination, captured by digitizing devices, is beneficial to solve many problems in computer graphics. Therefore, practical methods for capturing this illumination are of high interest. In this paper, we present a novel method for capturing environmental illumination by a mobile device. Our method is highly practical as it requires only a consumer mobile phone and the result can be instantly used for rendering or material estimation.We capture the real light in high dynamic range (HDR) to preserve its high contrast. Our method utilizes the moving camera of a mobile phone in auto-exposure mode to reconstruct HDR values. The projection of the image to the spherical environment map is based on the orientation of the mobile device. Both HDR reconstruction and projection run on the mobile GPU to enable interactivity. Moreover, an additional image alignment step is performed. Our results show that the presented method faithfully captures the real environment and that the rendering with our reconstructed environment maps achieves high quality, comparable to reality.
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    Interactive Pixel-Accurate Rendering of LR-Splines and T-Splines
    (The Eurographics Association, 2015) Hjelmervik, Jon M.; Fuchs, Franz G.; B. Bickel and T. Ritschel
    Flexible surface types on irregular grids, such as T-splines and LR-splines, are gaining popularity in science and industry due to the possibility for local grid refinement. We present a novel rendering algorithm for those surface types that guarantees pixel-accurate geometry and water-tight tessellation (no drop-outs). Before rendering, we extract the Bézier coefficients. The resulting irregular grids of Bézier patches are then rendered using a multistage algorithm, that decouples the tesselator and the patch geometry. The implementation using OpenGL utilizes compute shaders and hardware tessellation functionality. We showcase interactive rendering achieved by our approach on three representative use cases.