Precise Top View Image Generation without Global Metric Information

Hiroshi KANO  Keisuke ASARI  Yohei ISHII  Hitoshi HONGO  

IEICE TRANSACTIONS on Information and Systems   Vol.E91-D   No.7   pp.1893-1898
Publication Date: 2008/07/01
Online ISSN: 1745-1361
DOI: 10.1093/ietisy/e91-d.7.1893
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Section on Machine Vision and its Applications)
top view image,  homography,  calibration,  

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We describe a practical and precise calibration method for generating a top view image that is transformed so that a planar object such as the road can be observed from a direction perpendicular to its surface. The geometric relation between the input and output images is described by a 3 3 homography matrix. Conventional methods use large planar calibration patterns to achieve precise transformations. The proposed method uses much smaller element patterns that are placed in arbitrary positions within the view of the camera. One of the patterns is used to obtain an initial homography. Then, the information from all of the patterns is used by a non-linear optimization scheme to reach a global optimum homography. The experiment done to evaluate the method showed that the precision of the proposed method is comparable to that of the conventional method where a large calibration pattern is used, making it more practical for automotive applications.