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DEPTH-ORDER POINT CLASSIFICATION TECHNIQUES FOR CSG display algorithms

ACM TRANSACTIONS ON GRAPHICS 1991年第1期10卷 40-70页

作者： JANSEN, FW DELFT UNIV TECHNOL FAC IND DESIGN ENGNDELFTNETHERLANDS

Constructive Solid Geometry (CSG) defines objects as Boolean combinations (CSG trees) of primitive solids. To display such objects, one must classify points on the surfaces of the primitive solids with respect to the resulting composite object, to test whether these points lie on the boundary of the composite object or not. Although the point classification is trivial compared to the surface classification (i.e., the computation of the portion of the faces of primitive solids that lie on the boundary of the composite object), for CSG models with a large number of primitive solids (large CSG trees), the point classification may still consume a considerable fraction of the total processing time. This paper presents an overview of existing and new efficiency-improving techniques for classifying points in depth order. The different techniques are compared through experiments.

关键词： COMPUTATIONAL GEOMETRY AND OBJECT MODELING CONSTRUCTIVE SOLID GEOMETRY (CSG) CSG algorithms display algorithms SOLID MODELING 3-DIMENSIONAL GRAPHICS AND REALISM

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Style grammars for interactive visualization of architecture

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2007年第4期13卷 786-797页

作者： Aliaga, Daniel G. Rosen, Paul A. Bekins, Daniel R. Purdue Univ Dept Comp Sci W Lafayette IN 47906 USA

Interactive visualization of architecture provides a way to quickly visualize existing or novel buildings and structures. Such applications require both fast rendering and an effortless input regimen for creating and changing architecture using high-level editing operations that automatically fill in the necessary details. Procedural modeling and synthesis is a powerful paradigm that yields high data amplification and can be coupled with fast-rendering techniques to quickly generate plausible details of a scene without much or any user interaction. Previously, forward generating procedural methods have been proposed where a procedure is explicitly created to generate particular content. In this paper, we present our work in inverse procedural modeling of buildings and describe how to use an extracted repertoire of building grammars to facilitate the visualization and quick modification of architectural structures and buildings. We demonstrate an interactive application where the user draws simple building blocks and, using our system, can automatically complete the building "in the style of" other buildings using view-dependent texture mapping or non photo realistic rendering techniques. Our system supports an arbitrary number of building grammars created from user subdivided building models and captured photographs. Using only edit, copy, and paste metaphors, the entire building styles can be altered and transferred from one building to another in a few operations, enhancing the ability to modify an existing architectural structure or to visualize a novel building in the style of the others.

关键词： display algorithms image-based rendering modeling packages visualization systems and software

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Preserving attribute values on simplified meshes by resampling detail textures

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VISUAL COMPUTER 1999年第10期15卷 519-539页

作者： Cignoni, P Montani, C Rocchini, C Scopigno, R Tarini, M CNR Ist Elaborazione Informaz I-56126 Pisa Italy CNR Ist Elaborazione Informaz Pisa Italy Univ Pisa Dept Comp Sci I-56100 Pisa Italy

Many sophisticated solutions have been proposed to reduce the geometric complexity of 3D meshes. A slightly less studied problem is how to preserve attribute detail on simplified meshes (e.g., color. high-frequency shape derails, scalar fields, etc.). We present a general approach that is completely independent of the simplification technique adopted to reduce the mesh size. We use resampled textures (rgb, bump, displacement or shade maps) to decouple attribute detail representation from geometry simplification. The original contribution is that preservation is performed after simplification by building a set of triangular texture patches that are then packed into a single texture map. This general solution can be applied to the output of any topology-preserving simplification code and it allows any attribute value defined on the high-resolution mesh to be recovered. Moreover, decoupling shape simplification from detail preservation (and encoding the latter with texture maps) leads to high simplification rates and highly efficient rendering. We also describe an alternative application: the conversion of 3D models with 3D procedural textures (which generally force the use of software renderers) into standard 3D models with 2D bitmap textures.

关键词： surface simplification derail preservation texture mapping picture/image generation display algorithms

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Globally Optimized Linear Windowed Tone Mapping

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2010年第4期16卷 663-675页

作者： Shan, Qi Jia, Jiaya Brown, Michael S. Univ Washington Dept Comp Sci & Engn Paul G Allen Ctr 378 Seattle WA 98195 USA Chinese Univ Hong Kong Dept Comp Sci & Engn Shatin Hong Kong Peoples R China Natl Univ Singapore Sch Comp Singapore 117417 Singapore

This paper introduces a new tone mapping operator that performs local linear adjustments on small overlapping windows over the entire input image. While each window applies a local linear adjustment that preserves the monotonicity of the radiance values, the problem is implicitly cast as one of global optimization that satisfies the local constraints defined on each of the overlapping windows. Local constraints take the form of a guidance map that can be used to effectively suppress local high contrast while preserving details. Using this method, image structures can be preserved even in challenging high dynamic range (HDR) images that contain either abrupt radiance change, or relatively smooth but salient transitions. Another benefit of our formulation is that it can be used to synthesize HDR images from low dynamic range (LDR) images.

关键词： High dynamic range image tone mapping display algorithms image enhancement filtering

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Ray tracing deformed generalized cylinders

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VISUAL COMPUTER 2000年第3-4期16卷 197-207页

作者： de Voogt, E van der Helm, A Bronsvoort, WF Tech Univ Delft Fac Informat Technol & Syst NL-2628 BZ Delft Netherlands

Generalized cylinders are objects defined by sweeping a 2D contour along a 3D trajectory. We introduce deformed generalized cylinders in which different contours can be defined along the trajectory. The representation of a deformed generalized cylinder is suitable for directly ray tracing its shape;it need not be converted into another representation. A suitable algorithm and some resulting images are presented.

关键词： geometric modelling sweep objects generalized cylinders parametric surfaces cross-sectional design display algorithms ray tracing

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Real-time view-dependent image warping to correct non-linear distortion for curved Virtual Showcase displays

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COMPUTERS & GRAPHICS-UK 2003年第4期27卷 515-528页

作者： Bimber, O Fröhlich, B Schmalstieg, D Encarnaçao, LM Bauhaus Univ Weimar D-99423 Weimar Germany Vienna Univ Technol A-1040 Vienna Austria Fraunhofer Ctr Res Comp Graph Providence RI 02903 USA

We present a quadtree-based selective refinement algorithm for real-time, view-dependent image warping used to present images with mirror displays that require a non-linear predistortion. The algorithm applies two-pass rendering, and recursively generates and selectively refines the underlying image grid with locally adapted levels of detail. Each discrete level of detail is determined by computing and evaluating the displacement error on the image plane within the image space of the mirror optics. The algorithm generates and refines only those image portions that contain visible information by considering an oriented convex container of the rendered scene. While display specific details of the algorithm are explained based on the more complex case of a particular mirror display, the Virtual Showcase its general functionality is valid for other non-linear displays. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： display algorithms viewing algorithms hierarchy and geometric transformations augmented and virtual realities

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A Programmable display Layer for Virtual Reality System Architectures

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2010年第1期16卷 28-42页

作者： Smit, Ferdi Alexander van Liere, Robert Froehlich, Bernd Ctr Wiskunde & Informat NL-1090 GB Amsterdam Netherlands Bauhaus Univ Weimar D-99423 Weimar Germany

display systems typically operate at a minimum rate of 60 Hz. However, existing VR-architectures generally produce application updates at a lower rate. Consequently, the display is not updated by the application every display frame. This causes a number of undesirable perceptual artifacts. We describe an architecture that provides a programmable display layer (PDL) in order to generate updated display frames. This replaces the default display behavior of repeating application frames until an update is available. We will show three benefits of the architecture typical to VR. First, smooth motion is provided by generating intermediate display frames by per-pixel depth-image warping using 3D motion fields. Smooth motion eliminates various perceptual artifacts due to judder. Second, we implement fine-grained latency reduction at the display frame level using a synchronized prediction of simulation objects and the viewpoint. This improves the average quality and consistency of latency reduction. Third, a crosstalk reduction algorithm for consecutive display frames is implemented, which improves the quality of stereoscopic images. To evaluate the architecture, we compare image quality and latency to that of a classic level-of-detail approach.

关键词： display algorithms virtual reality image-based rendering

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Biopsy Planner - Visual Analysis for Needle Pathway Planning in Deep Seated Brain Tumor Biopsy

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COMPUTER GRAPHICS FORUM 2012年第3期31卷 1085-1094页

作者： Herghelegiu, P. C. Manta, V. Perin, R. Bruckner, S. Groeller, E. Gheorghe Asachi Tech Univ Iasi Iasi Romania Clin Emergency Hosp Bagdasar Arseni Bucharest Romania Vienna Univ Technol Inst Comp Graph & Algorithms A-1040 Vienna Austria

Biopsies involve taking samples from living tissue using a biopsy needle. In current clinical practice they are a first mandatory step before any further medical actions are planned. Performing a biopsy on a deep seated brain tumor requires considerable time for establishing and validating the desired biopsy needle pathway to avoid damage. In this paper, we present a system for the visualization, analysis, and validation of biopsy needle pathways. Our system uses a multi-level approach for identifying stable needle placements which minimize the risk of hitting blood vessels. This is one of the major dangers in this type of intervention. Our approach helps in identifying and visualizing the point on the pathway that is closest to a surrounding blood vessel, requiring a closer inspection by the neurosurgeon. An evaluation by medical experts is performed to demonstrate the utility of our system.

关键词： I.3.3 [Computer Graphics]: Picture/Image Generation display algorithms

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Multifocal projection: A multiprojector technique for increasing focal depth

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2006年第4期12卷 658-667页

作者： Bimber, O Emmerling, A Bauhaus Univ Weimar D-99423 Weimar Germany

In this paper, we describe a novel multifocal projection concept that applies conventional video projectors and camera feedback. Multiple projectors with differently adjusted focal planes, but overlapping image areas are used. They can be either differently positioned in the environment or can be integrated into a single projection unit. The defocus created on an arbitrary surface is estimated automatically for each projector pixel. If this is known, a final image with minimal defocus can be composed in real-time from individual pixel contributions of all projectors. Our technique is independent of the surfaces' geometry, color and texture, the environment light, as well as of the projectors' position, orientation, luminance, and chrominance.

关键词： computing methodologies computer graphics picture/image generation digitizing and scanning display algorithms image processing and computer vision digitization and image capture radiometry reflectance sampling scanning enhancement sharpening and deblurring scene analysis color shape

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GENERATING EXACT RAY-TRACED ANIMATION FRAMES BY REPROJECTION

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IEEE COMPUTER GRAPHICS AND APPLICATIONS 1995年第3期15卷 43-52页

作者： ADELSON, SJ HODGES, LF GEORGIA INST TECHNOL COLL COMPATLANTAGA 30332 GEORGIA INST TECHNOL CTR GRAP VISUALIZAT & USABILATLANTAGA 30332

Reprojection techniques can create approximate ray traced animation frames. Extending an existing algorithm yields exact frames and full ray tracing, with up to 92 percent savings in rendering time. We present an algorithm that exploits spatiotemporal coherence between frames to significantly decrease the rendering time of ray traced animations. This method produces inferred ray traced images of any scene that can be ray traced using a point sampled method. The images created by the algorithm are not approximated frames created from weighted averages of other frames, nor are they frames patched together from near frame pixel values. The algorithm guarantees that a color seen in a subpixel would be returned by a ray passing somewhere through that subpixel, but not necessarily though the center. This algorithm efficiently creates frames of any view that can be ray traced. While the savings increase with the complexity of the rendered objects and the preponderance of diffuse objects, significant savings occur with reflective and refractive objects. However, the technique requires the ray tracing method to be point sample oriented

关键词： display algorithms Ray Traced Animation Spatial Coherence Temporal Coherence

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