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Combining polygonal and subdivision surface approaches to modelling and rendering of urban environments

COMPUTERS & GRAPHICS-UK 2004年第4期28卷 497-507页

作者： Day, AM Arnold, DB Havemann, S Fellner, DW Univ E Anglia Sch Comp Sci Norwich NR2 2DF Norfolk England Univ Brighton Brighton BN2 4AT E Sussex England Braunschweig Univ Technol Braunschweig Germany

The economic production and the interactive rendering of complete reconstructions of populated urban environments are technically difficult tasks. Specialized modelling tools, which exploit knowledge of the types of object being modelled by working in the application domain, can be used to create appealing virtual reconstructions quickly. At the same time, the structural information from the modeller gives valuable hints to the renderer to determine efficient interactive display strategies through the use of level-of-detail and culling techniques. Thus a modeller that knows the operator is creating houses can use this information to simplify the user interaction, guide the operator, and to create models that build in optimizations when attempting real-time rendering. In this paper we discuss the way in which polygonal and multi-resolution surface techniques can complement one another in the modelling of urban environments. We also draw more general conclusions which apply to other software systems that share the same objective. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： display algorithms viewing algorithms curve, surface, solid and object representations

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Seamless Video Stitching from Hand-held Camera Inputs

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COMPUTER GRAPHICS FORUM 2016年第2期35卷 479-487页

作者： Lin, Kaimo Liu, Shuaicheng Cheong, Loong-Fah Zeng, Bing Natl Univ Singapore Singapore 117548 Singapore Univ Elect Sci & Technol China Beijing Peoples R China

Images/videos captured by portable devices (e.g., cellphones, DV cameras) often have limited fields of view. Image stitching, also referred to as mosaics or panorama, can produce a wide angle image by compositing several photographs together. Although various methods have been developed for image stitching in recent years, few works address the video stitching problem. In this paper, we present the first system to stitch videos captured by hand-held cameras. We first recover the 3D camera paths and a sparse set of 3D scene points using CoSLAM system, and densely reconstruct the 3D scene in the overlapping regions. Then, we generate a smooth virtual camera path, which stays in the middle of the original paths. Finally, the stitched video is synthesized along the virtual path as if it was taken from this new trajectory. The warping required for the stitching is obtained by optimizing over both temporal stability and alignment quality, while leveraging on 3D information at our disposal. The experiments show that our method can produce high quality stitching results for various challenging scenarios.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.3 [Computer Graphics]: Picture/Image Generation&mdash viewing algorithms I.4.8 [Image Processing and Computer Vision]: Scene Analysis&mdash Stereo

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A GPU-based Approach for Massive Model Rendering with Frame-to-Frame Coherence

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COMPUTER GRAPHICS FORUM 2012年第2期31卷 393-402页

作者： Peng, Chao Cao, Yong Virginia Tech Dept Comp Sci Blacksburg VA 24061 USA

Rendering massive 3D models in real-time has long been recognized as a very challenging problem because of the limited computational power and memory space available in a workstation. Most existing rendering techniques, especially level of detail (LOD) processing, have suffered from their sequential execution natures. We present a GPU-based approach which enables interactive rendering of large 3D models with hundreds of millions of triangles. Our work contributes to the massive rendering research in two ways. First, we present a simple and efficient mesh simplification algorithm towards GPU architecture. Second, we propose a novel GPU out-of-core approach that adopts a frame-to-frame coherence scheme in order to minimize the high communication cost between CPU and GPU. Our results show that the parallel algorithm of mesh simplification and the GPU out-of-core approach significantly improve the overall rendering performance.

关键词： I.3.3 [Computer Graphics]: Picture/Image Generation&mdash viewing algorithms I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling&mdash Geometric algorithms

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Hallucinating Stereoscopy from a Single Image

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COMPUTER GRAPHICS FORUM 2015年第2期34卷 1-12页

作者： Zeng, Qiong Chen, Wenzheng Wang, Huan Tu, Changhe Cohen-Or, Daniel Lischinski, Dani Chen, Baoquan Shandong Univ Jinan 250100 Shandong Peoples R China Tel Aviv Univ IL-69978 Tel Aviv Israel Hebrew Univ Jerusalem IL-91905 Jerusalem Israel

We introduce a novel method for enabling stereoscopic viewing of a scene from a single pre-segmented image. Rather than attempting full 3D reconstruction or accurate depth map recovery, we hallucinate a rough approximation of the scene's 3D model using a number of simple depth and occlusion cues and shape priors. We begin by depth-sorting the segments, each of which is assumed to represent a separate object in the scene, resulting in a collection of depth layers. The shapes and textures of the partially occluded segments are then completed using symmetry and convexity priors. Next, each completed segment is converted to a union of generalized cylinders yielding a rough 3D model for each object. Finally, the object depths are refined using an iterative ground fitting process. The hallucinated 3D model of the scene may then be used to generate a stereoscopic image pair, or to produce images from novel viewpoints within a small neighborhood of the original view. Despite the simplicity of our approach, we show that it compares favorably with state-of-the-art depth ordering methods. A user study was conducted showing that our method produces more convincing stereoscopic images than existing semi-interactive and automatic single image depth recovery methods.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.7 [Computer Graphics]: Picture/Image Generation&mdash viewing algorithms I.4.8 [Image Processing and Computer Vision]: Scene Analysis&mdash depth cues

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Unstructured Light Fields

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COMPUTER GRAPHICS FORUM 2012年第2期31卷 305-314页

作者： Davis, Abe Levoy, Marc Durand, Fredo Stanford Univ Stanford CA 94305 USA

We present a system for interactively acquiring and rendering light fields using a hand-held commodity camera. The main challenge we address is assisting a user in achieving good coverage of the 4D domain despite the challenges of hand-held acquisition. We define coverage by bounding reprojection error between viewpoints, which accounts for all 4 dimensions of the light field. We use this criterion together with a recent Simultaneous Localization and Mapping technique to compute a coverage map on the space of viewpoints. We provide users with real-time feedback and direct them toward under-sampled parts of the light field. Our system is lightweight and has allowed us to capture hundreds of light fields. We further present a new rendering algorithm that is tailored to the unstructured yet dense data we capture. Our method can achieve piecewise-bicubic reconstruction using a triangulation of the captured viewpoints and subdivision rules applied to reconstruction weights.

关键词： Computer Graphics [1.3.3]: Picture/Image Generation&mdash Digitizing and Scanning viewing algorithms

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Inexpensive immersive projection

Inexpensive immersive projection

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IEEE Virtual Reality 2008 Conference

作者： Yuen, Nancy P. Y. Thibault, William C. Calif State Univ E Bay Hayward CA USA

ISBN: (纸本)9781424419715

Most projector-based immersive displays have numerous problems relating to complexity, space, and cost. We present a technique for rendering perspectively correct images using a casual arrangement of a projector, a mirror and a display surface. Our technique renders an arbitrarily wide field of view using an efficient GPU-based single-pass rendering algorithm. The rendering algorithm is preceded by a one-time camera-based geometric correction calibration step. As we will describe, this technique can be implemented with inexpensive, commodity hardware and using readily available display surfaces. Thus, this technique enables immersive projection systems to be used in casual locations, such as a classroom or even in the home.

关键词： display algorithms viewing algorithms camera calibration projector-camera systems

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Large volume visualization of compressed time-dependent datasets on GPU clusters

Large volume visualization of compressed time-dependent data...

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Symposium on Parallel Graphics and Visualization

作者： Strengert, M Magallón, M Weiskopf, D Guthe, S Ertl, T Univ Stuttgart Inst Visualizat & Interact Syst D-70569 Stuttgart Germany Univ Costa Rica Escuela Fis San Pedro 2060 Costa Rica Univ Tubingen GRIS WSI D-72076 Tubingen Germany

We describe a system for the texture-based direct volume visualization of large data sets on a PC cluster equipped with GPUs. The data is partitioned into volume bricks in object space, and the intermediate images are combined to a final picture in a sort-last approach. Hierarchical wavelet compression is applied to increase the effective size of volumes that can be handled. An adaptive rendering mechanism takes into account the viewing parameters and the properties of the data set to adjust the texture resolution and number of slices. We discuss the specific issues of this adaptive and hierarchical approach in the context of a distributed memory architecture and present corresponding solutions. Furthermore, our compositing scheme takes into account the footprints of volume bricks to minimize the costs for reading from framebuffer, network communication, and blending. A detailed performance analysis is provided for several network, CPU, and GPU architectures-and scaling characteristics of the parallel system are discussed. For example, our tests on a eight-node AMD64 cluster with InfiniBand show a rendering speed of 6 frames per second for a 2048 x 1024 x 1878 data set on a 1024(2) viewport. (c) 2005 Elsevier B.V. All rights reserved.

关键词： graphics systems distributed/network graphics viewing algorithms

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Virtual Tubelets -: Efficiently visualizing large amounts of particle trajectories

<i>Virtual Tubelets</i> -: Efficiently visualizing large amo...

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International Conference on Virtual Reality Continuum and Its Applications in Industry (VRCIA)

作者： Schirski, M Kuhlen, T Hopp, M Adomeit, P Pischinger, S Bischof, C Univ Aachen Rhein Westfal TH Aachen Ctr Comp & Commun D-52074 Aachen Germany FEV Motorentech GmbH D-52078 Aachen Germany Univ Aachen Rhein Westfal TH Aachen Inst Internal Combust Engines VKA D-52062 Aachen Germany

The depiction of particle trajectories is an effective means for the visualization of fluid flows. However, standard visualization techniques suffer from a variety of weaknesses, ranging from ambiguous depth perception for simple line drawings to a high geometrical complexity and decreased interactivity for polygonal tubes. This paper addresses these problems by introducing a novel approach to pathline visualization, which we call Virtual Tubelets. It employs billboarding techniques in combination with suitable textures in order to create the illusion of solid tubes, thus efficiently and unambiguously depicting large amounts of particle trajectories at interactive frame rates. By choosing an appropriate orientation for the billboards, certain issues concerning immersive displays with multiple projection screens are resolved, which allows for an unrestricted use in virtual environments as well. Using modern graphics hardware with programmable vertex and pixel pipelines results in an additional speed-up of the rendering process and a further improvement of image quality. This creates a nearly perfect illusion of tubular geometry, including plausible intersections and consistent illumination with the rest of the scene. The efficiency of our approach is proven by comparing rendering speed and visual quality of Virtual Tubelets to that of conventional, polygonal tube renderings. (c) 2004 Elsevier Ltd. All rights reserved.

关键词： virtual reality scientific data visualization viewing algorithms programmable graphics hardware

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Combining polygonal and subdivision surface approaches to modelling and rendering of urban environments

Combining polygonal and subdivision surface approaches to mo...

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International Conference on Cyberworlds (CW 2003)

ISBN: (纸本)0769519229

关键词： display algorithms viewing algorithms curve, surface, solid and object representations

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Improving occlusion query efficiency with occupancy maps 03

Improving occlusion query efficiency with occupancy maps

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IEEE Symposium on Parallel and Large-Data Visualization and Graphics

作者： Staneker, D Bartz, D Meissner, M Univ Tubingen WSI GRIS Tubingen Germany

ISBN: (纸本)078038122X

Image space occlusion culling is an useful approach to reduce the rendering load of large polygonal models. Like most large model techniques, it trades overhead costs with the rendering costs of the possibly occluded geometry. Meanwhile, modem graphics hardware supports occlusion culling, whereas they associate a significant query overhead, which hurts in particular, if the occlusion culling query itself was unsuccessful. In this paper, we propose the Occupancy Map - a compact, cache-optimized representation of coverage information - to reduce the number of costly but unsuccessful occlusion culling queries and to arrange multiple occlusion queries. The information of the Occupancy Map is used to skip an occlusion query, if the respective map area is not yet set - the respective area has not yet received rendered pixels -, hence an occlusion query would always return not occluded. The remaining occlusion information is efficiently determined by asynchronous multiple occlusion queries with hardware-supported query functionality. To avoid redundant results, we arrange these multiple occlusion queries according to the information of several Occupancy Maps. Our presented technique is conservative and benefits from a partial depth order of the geometry.

关键词： viewing algorithms occlusion culling

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