A Stereo Vision System for Top View Book Scanners
A Stereo Vision System for Top View Book Scanners
复制标题
用于顶视图书籍扫描仪的立体视觉系统
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
B. Michaelis
中科院分区：
文献类型：
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作者：
Erik Lilienblum;R. Niese;B. Michaelis
摘要-本文提出了一种新的立体视觉技术的顶视图图书扫描仪，为我们提供了密集的三维点云的页面表面。这是一个独立于页面上的2d信息对边界卷进行解扭曲的先决条件。我们的方法是基于算法，这通常需要投影的图案序列与结构光。我们使用顶视扫描仪的移动条纹照明的图像序列，而不是额外的光投影。因此，立体视觉设置简化了艾德，而不损失测量精度。通过引入基于真实的测量值的差分向量，改进了一种表面模型去翘曲方法。虽然我们提出的方法在计算时间和硬件要求上都很昂贵，但即使对于困难的例子，我们也能得到很好的去扭曲结果。关键词立体视觉，三维表面重建，文件去翘曲，图书扫描仪。引言自从有了文档副本以来，从装订的卷中获取页面副本的问题就一直存在。在处理双床扫描仪时存在严重的问题。通常用户必须将书籍压在玻璃板上，这可能导致书脊损坏。而且一般来说，复制的结果并不令人信服。由于这个原因，一种特殊的图书扫描仪，这是所谓的顶视扫描仪，成为普遍接受在过去的十年。为了以自然的方式使用这些书，这些扫描仪从上方和一定距离处捕获页面的副本。通过使用一个线阵相机与一个适当的条纹照明，它是可能的接收均匀清晰和良好照明的二维图像。使用顶视图图书扫描仪的主要问题是dewarping问题，因为我们不可避免地得到一个扭曲的副本在扫描仪的投影几何和页面的翘曲表面的后果。有许多不同种类的矫正技术。最强大但也最昂贵的技术是使用立体视觉方法来重建页面的3d表面[1]，[2]，[3]。表面重构是对版面二维图像进行去畸变的最佳基础。通常它适用于任意文档[4]。无立体视觉设置的情况下，可使用双通道方法。知名
Abstract —This paper proposes a novel stereo vision techniquefor top view book scanners which provide us with dense 3d pointclouds of page surfaces. This is a precondition to dewarp boundvolumes independent of 2d information on the page. Our method isbased on algorithms, which normally require the projection of patternsequences with structured light. We use image sequences of themoving stripe lighting of the top view scanner instead of an additionallight projection. Thus the stereo vision setup is simplified withoutlosing measurement accuracy. Furthermore we improve a surfacemodel dewarping method through introducing a difference vectorbased on real measurements. Although our proposed method is hardlyexpensive neither in calculation time nor in hardware requirementswe present good dewarping results even for difficult examples. Keywords —stereo vision, 3d surface reconstruction, dewarpingdocuments, book scanner I. I NTRODUCTION The issue of getting page copies from bound volumes hasbeen existing since document copies were available at all.There are serious problems dealing with flat bed scanners.Commonly the user has to press the book on a glass plate,which may lead to damage of the book spine. And in general,the copy results are not convincing. For this reason a specialkind of book scanner, which is called top view scanner, becamegenerally accepted in the last decade. To use the books in theirnatural way those scanners capture a copy of the page fromabove and from a certain distance. Through the use of a linecamera with an appropriate stripe lighting it is possible toreceive an evenly sharp and well illuminated two-dimensionalimage.The main problem using top view book scanners is thedewarping problem, because we inevitably get a distorted copyin consequence of the projective geometry of the scanner andthe warped surface of the page. There are many different kindsof dewarping techniques. The most powerful but also mostexpensive technique uses stereo vision methods to reconstructthe 3d surface of the page [1], [2], [3]. The surface recon-struction is the best basis for dewarping an 2d image of thepage. Normally it works for arbitrary documents [4]. Otherapproaches work without a stereo vision setup. Well-known