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Efficient Methods for Tile-Based Synthesis and Computational Photography

Efficient Methods for Tile-Based Synthesis and Computational Photography

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KOPF, Johannes, 2008. Efficient Methods for Tile-Based Synthesis and Computational Photography [Dissertation]. Konstanz: University of Konstanz

@phdthesis{Kopf2008Effic-5871, title={Efficient Methods for Tile-Based Synthesis and Computational Photography}, year={2008}, author={Kopf, Johannes}, address={Konstanz}, school={Universität Konstanz} }

2011-03-24T16:00:52Z 2008 eng terms-of-use application/pdf This thesis presents contributions to two major topics in computer graphics. The first part describes new algorithms for tile-based synthesis of blue noise point sets and solid textures; the second part describes systems for capturing, viewing, and manipulating outdoor photographs.<br /><br />Well distributed point sets play an important role in computer graphics, as well as many other fields, since they lie in the very foundation of any sampling technique. Many previous researchers have pointed out that point sets with a blue noise Fourier spectrum, i.e. the points are distributed both evenly and randomly, are desirable in many applications.<br /><br />In this thesis, we introduce a novel technique for rapidly generating such point sets. Through the use of Wang tiles, our technique deterministically generates infinite non-periodic patterns. Any local area may be consistently regenerated as needed. The points in each tile form a progressive sequence, enabling matching arbitrary spatially varying point densities. Recursion allows our technique to adaptively subdivide tiles where high density is required, and makes it possible to zoom into point sets by an arbitrary amount, while maintaining a constant apparent density. The technique is extremely fast (point generation is in the order of several millions of points per second) and has a compact memory footprint. These properties make our technique highly suitable for a variety of real-time interactive applications, some of which are demonstrated in this thesis.<br /><br />Another area where tiling techniques are commonly utilized is texture synthesis. While 2D texture synthesis has been heavily researched in the past decade, synthesis of high quality solid textures remained a mostly unsolved problem. We present a novel method for synthesizing solid textures from 2D texture exemplars. First, we extend 2D texture optimization techniques to synthesize 3D texture solids. Next, the non-parametric texture optimization approach is integrated with histogram matching, which forces the global statistics of the synthesized solid to match those of the exemplar. This approach improves the convergence speed of the synthesis process and the quality of the synthesized results drastically. Our method is applicable to a wide variety of textures, including anisotropic textures, textures with large coherent structures, and multi-channel textures.<br /><br />The second part of the thesis describes systems for capturing, viewing, and manipulating outdoor photographs.<br /><br />First, we present a system to capture and view Gigapixel images'' (very high resolution, high dynamic range, and wide angle imagery consisting of several billion pixels each). We use a specialized camera mount, in combination with an automated pipeline for alignment, exposure compensation, and stitching, to acquire Gigapixel images with a standard camera and lens. We also present a novel viewer that enables exploration of such images at interactive rates over a network, while dynamically and smoothly interpolating the projection between perspective and curved projections, and simultaneously modifying the tone mapping to ensure an optimal view of the portion of the scene being viewed.<br /><br />An important aspect of working with large imagery is how to deal with computational and memory constraints when processing the images. Image analysis and enhancement tasks such as tone mapping, colorization, stereo depth, and photomontage, often require computing a solution (e.g., for exposure, chromaticity, disparity, labels) over the pixel grid. When processing large images (e.g. our Gigapixel images) computational and memory costs often require that the solution is computed on downsampled versions of the images. Once the solution for a downsampled image is available it has to be upsampled to the full original resolution of the input image. Solutions upsampled with general purpose upsampling filters suffer from blurring of sharp edges because of the smoothness priors inherent in those filters. We demonstrate that in cases, such as those above, the available high resolution input image may be leveraged as a prior in the context of a joint bilateral upsampling'' procedure to generate a better high resolution solution. We show results for each of the applications mentioned above and compare them to traditional upsampling methods.<br /><br />Finally, we introduce a novel method for browsing, enhancing, and manipulating outdoor photographs by combining them with existing geo-referenced digital terrain and urban models. A simple interactive registration process is used to align photographs with models. Once the photograph and the model have been registered, an abundance of information, such as depth, texture, and geographical data, becomes immediately available to our system. This information, in turn, enables a variety of operations, ranging from dehazing and relighting the photograph, to novel view synthesis, and overlaying with geographic information. We describe the implementation of a number of these applications and discuss possible extensions. Our results show that augmenting photographs with 3D models in this manner supports a wide variety of new ways for us to experience and interact with our everyday snapshots. Kopf, Johannes 2011-03-24T16:00:52Z Kopf, Johannes Effiziente Algorithmen für Tile-basierte Synthese und Computational Photography Efficient Methods for Tile-Based Synthesis and Computational Photography

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