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2010. 2. 26. 00:07 Computer Vision
Optimal Grid Pattern for Automated Camera Calibration Using Cross Ratio

Chikara MATSUNAGA  Yasushi KANAZAWA  Kenichi KANATANI 

Publication IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences  Vol.E83-A  No.10  pp.1921-1928
Publication Date: 2000/10/20
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Information Theory and Its Applications)
Category: Image Processing
Keyword: cross ratioMarkov processerror analysisreliability evaluationvirtual studio
Full Text:
출처:  http://www.suri.it.okayama-u.ac.jp/~kanatani/data/ejournal.html

MVA2000 IAPR Workshop on Machine Vision Applications, Nov. 28-30,2000, The University of Tokyo, Japan
13-28
Optimal Grid Pattern for Automated Matching Using Cross Ratio
Chikara Matsunaga (Broadcast Division, FOR-A Co. Ltd.)
Kenichi Kanatanit (Department of Computer Science, Gunma University)


Kenichi Kanatani  金谷健一   http://www.suri.it.okayama-u.ac.jp/%7Ekanatani/
Yasushi Kanazawa 金澤靖     http://www.img.tutkie.tut.ac.jp/~kanazawa/

IEICE (
The Institute of Electronics Information and Communication Engineers)   http://www.ieice.org
IAPR (International Association of Pattern Recognition)   http://www.iapr.org
IAPR - Machine Vision & Applications



Summary: 
With a view to virtual studio applications, we design an optimal grid pattern such that the observed image of a small portion of it can be matched to its corresponding position in the pattern easily. The grid shape is so determined that the cross ratio of adjacent intervals is different everywhere. The cross ratios are generated by an optimal Markov process that maximizes the accuracy of matching. We test our camera calibration system using the resulting grid pattern in a realistic setting and show that the performance is greatly improved by applying techniques derived from the designed properties of the pattern.


Camera calibration is a first step in all vision and media applications.
> pre-calibration (Tsai) vs. self-calibration (Pollefeys)
=> "simultaneous calibration" by placing an easily distinguishable planar pattern in the scene

Introducing a statistic model of image noise, we generate the grid intervals by an optimal Markov process that maximizes the accuracy of matching.
: The pattern is theoretically designed by statistical analysis

If the cross rations are given, the sequence is determined as follows.


To find a sequence of cross ratios such that the sequence of numbers is a homogeneous increasing with the average interval being 1 and the minimum width as specified.
=> To generate the sequence of cross ratios stochastically, according to a probability distribution defined in such a way that the resulting sequence of numbers has the desired properties
=> able to optimize the probability distribution so that the matching performance is maximized by analyzing the statistical properties of image noise

 



 

출처: C. Matsunaga, Y. Kanazawa, and K. Kanatani, Optimal grid pattern for automated camera calibration using cross ratio , IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E83-A, No. 10, pp. 1921--1928, 2000. 중 1926쪽 Fig.8 4배 확대 캡처





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posted by maetel