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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
2009. 9. 2. 17:51 Computer Vision
전자통신동향분석 22권 4호 (통권 106호) (발행일 : 2007.08)
모바일 혼합현실 기술 (Mobile Mixed Reality Technology)

저     자: 김기홍, 김홍기, 정혁, 김종성, 손욱호 / 가상현실연구팀
발행일자: 2007.08.15
발행권호: 22권 4호 (통권 106)
페 이 지: 96
논문구분: 융합 시대를 주도할 디지털콘텐츠 기술 특집 논문

초     록
혼합현실 기술을 휴대가 용이한 모바일 기기상에서 효과적으로 구현하기 위해서는 기기에 부착된 카메라의 위치를 인식하는 기술을 시작으로 입력된 실세계 공간에 가상의 디지털 정보를 정합하고 표현하는 기술, 사용자가 표현된 혼합현실 환경과 현실감있게 상호작용하는 기술, 그리고 다양한 응용분야에 맞게 혼합현실 콘텐츠를 저작하는 기술에 이르기까지 여러 가지 세부 기술들이 요구된다. 본 논문에서는 언급한 세부 기술들에 대한 개요와 국내외적으로 진행되고 있는 관련 기술들의 동향을 구체적인 사례를 통해 소개한다.
 
 
ARToolKit (Augmented Reality Tool Kit)
http://www.hitl.washington.edu/artoolkit/
software library for building Augmented Reality (AR) applications

MR-Platform

MxToolKit

ARTag
http://www.artag.net/

OSGART
http://www.osgart.org/
http://www.artoolworks.com/community/osgart/
C++ cross-platform development library that simplifies the development of Augmented Reality or Mixed Reality applications by combining computer vision based tracking libraries (e.g. ARToolKit, ARToolKitPlus, SSTT and BazAR) with the 3D scene graph libary OpenSceneGraph

AMIRE
http://www.amire.net/
http://sourceforge.net/projects/amire/
project about the efficient creation and modification of augmented reality (AR) and mixed reality (MR) applications

APRIL (Augmented Presentation and Interaction Authoring Language)
http://studierstube.icg.tu-graz.ac.at/april/
http://www.icg.tugraz.at/pub/APRIL
high-level descriptive language for authoring presentations in augmented reality (AR)

DART (The Designer's Augmented Reality Toolkit)
http://www.cc.gatech.edu/dart/
a set of software tools that support rapid design and implementation of augmented reality experiences and applications

ULTRA (Ultra portable augmented reality for industrial maintenance applications)
http://www.ist-ultra.org/


Authoring Tool

CMIL++




posted by maetel
2009. 7. 14. 21:23 Computer Vision
ISMAR 2008
7th IEEE/ACM International Symposium on Mixed and Augmented Reality, 2008


Proceedings
State of the Art Report

Trends in Augmented Reality Tracking, Interaction and Display
: A Review of Ten Years of ISMAR
Feng Zhou (Center for Human Factors and Ergonomics, Nanyang Technological University, Singapore)
Henry Been-Lirn Duh (Department of Electrical and Computer Engineering/Interactive and Digital Media Institute, National University of Singapore)
Mark Billinghurst (The HIT Lab NZ, University of Canterbury, New Zealand)


Tracking

1. Sensor-based tracking -> ubiquitous tracking and dynamic data fusion

2. Vision-based tracking: feature-based and model-based
1) feature-based tracking techniques:
- To find a correspondence between 2D image features and their 3D world frame coordinates.
- Then to find the camera pose from projecting the 3D coordinates of the feature into the observed 3D image coordinates and minimizing the distance to their corresponding 3D features.

2) model-based tracking techniques:
- To explicitly use a model of the features of tracked objects such as a CAD model or 2D template of the object based on the distinguishable features.
- A visual serving approach adapted from robotics to calculate camera pose from a range of model features (line, circles, cylinders and spheres)
- knowledge about the scene by predicting hidden movement of the object and reducing the effects of outlier data

3. Hybrid tracking
- closed-loop-type tracking based on computer vision techonologies
- motion prediction
- SFM (structure from motion)
- SLAM (simultaneous localization and mapping)


Interaction and User Interfaces

1. Tangible
2. Collaborative
3. Hybrid


Display

1. See-through HMDs
1) OST = optical see-through
: the user to see the real world with virtual objects superimposed on it by optical or video technologies
2) VST = video see-through
: to display graphical infromation directly on real objects or even daily surfaces in everyday life
2. Projection-based Displays
3. Handheld Displays


Limitations of AR

> tracking
1) complexity of the scene and the motion of target objects, including the degrees of freedom of individual objects and their represenation
=> correspondence analysis: Kalman filters, particle filters.
2) how to find distinguishable objects for "markers" outdoors

> interaction
ergonomics, human factors, usability, cognition, HCI (human-computer interaction)

> AR displays
- HMDs - limited FOV, image distortions,
- projector-based displays - lack mobility, self-occlusion
- handheld displays - tracking with markers to limit the work range

Trends and Future Directions

1. Tracking
1) RBPF (Rao-Blackwellized particle filters) -> automatic recognition systems
2) SLAM, ubiquitous tracking, sensor network -> free from prior knowledge
3) pervasive middleware <- information fusion algorithms

2. Interaction and User Interfaces
"Historically, human knowledge, experience and emotion are expressed and communicated in words and pictures. Given the advances in interface and data capturing technology, knowledge, experience and emotion might now be presented in the form of AR content."

3. AR Displays





Studierstube Augmented Reality Project
: software framework for the development of Augmented Reality (AR) and Virtual Reality applications
Graz University of Technology (TU Graz)

Sharedspace project
The Human Interface Technology Laboratory (HITLab) at the University ofWashington and ATR Media Integration & Communication in Kyoto,Japan join forces at SIGGRAPH 99

The Invisible Train - A Handheld Augmented Reality Game

AR Tennis
camera based tracking on mobile phones in face-to-face collaborative Augmented Reality

Emmie - Environment Management for Multi-User Information Environments

VITA: visual interaction tool for archaeology

HMD = head-mounted displays

OST = optical see-through

VST = video see-through

ELMO: an Enhanced optical see-through display using an LCD panel for Mutual Occlusion

FOV
http://en.wikipedia.org/wiki/Field_of_view_(image_processing)

HMPD = head-mounted projective displays

The Touring Machine

MARS - Mobile Augmented Reality Systems
    
Klimt - the Open Source 3D Graphics Library for Mobile Devices

AR Kanji - The Kanji Teaching application


references  
Ronald T. Azuma  http://www.cs.unc.edu/~azuma/
A Survey of Augmented Reality. Presence: Teleoperators and Virtual Environments 6, 4 (August 1997), 355 - 385. Earlier version appeared in Course Notes #9: Developing Advanced Virtual Reality Applications, ACM SIGGRAPH '95 (Los Angeles, CA, 6-11 August 1995), 20-1 to 20-38.

Ronald Azuma, Yohan Baillot, Reinhold Behringer, Steven Feiner,Simon Julier, Blair MacIntyre
Recent Advances in Augmented Reality.IEEE Computer Graphics and Applications 21, 6 (Nov/Dec 2001),34-47.

Ivan E. Sutherland
The Ultimate Display, IFIP `65, pp. 506-508, 1965

Kato, H.   Billinghurst, M.   Poupyrev, I.   Imamoto, K.   Tachibana, K.   Hiroshima City Univ.
Virtual object manipulation on a table-top AR environment

Sandor, C., Olwal, A., Bell, B., and Feiner, S. 2005.
Immersive Mixed-Reality Configuration of Hybrid User Interfaces.
In Proceedings of the 4th IEEE/ACM international Symposium on Mixed and Augmented Reality(October 05 - 08, 2005). Symposium on Mixed and Augmented Reality. IEEEComputer Society, Washington, DC, 110-113. DOI=http://dx.doi.org/10.1109/ISMAR.2005.37

An optical see-through display for mutual occlusion with a real-time stereovision system
Kiyoshi Kiyokawa, Yoshinori Kurata and Hiroyuki Ohno
Computers & Graphics Volume 25, Issue 5, October 2001, Pages 765-779

Bimber, O., Fröhlich, B., Schmalstieg, D., and Encarnação, L. M. 2005.
The virtual showcase. In ACM SIGGRAPH 2005 Courses (Los Angeles, California, July 31 - August 04, 2005). J. Fujii, Ed. SIGGRAPH '05. ACM, New York, NY, 3. DOI= http://doi.acm.org/10.1145/1198555.1198713

Bimber, O., Wetzstein, G., Emmerling, A., and Nitschke, C. 2005.
Enabling View-Dependent Stereoscopic Projection in Real Environments. In Proceedings of the 4th IEEE/ACM international Symposium on Mixed and Augmented Reality (October 05 - 08, 2005). Symposium on Mixed and Augmented Reality. IEEE Computer Society, Washington, DC, 14-23. DOI= http://dx.doi.org/10.1109/ISMAR.2005.27

Cotting, D., Naef, M., Gross, M., and Fuchs, H. 2004.
Embedding Imperceptible Patterns into Projected Images for Simultaneous Acquisition and Display. In Proceedings of the 3rd IEEE/ACM international Symposium on Mixed and Augmented Reality (November 02 - 05, 2004). Symposium on Mixed and Augmented Reality. IEEE Computer Society, Washington, DC, 100-109. DOI= http://dx.doi.org/10.1109/ISMAR.2004.30

Ehnes, J., Hirota, K., and Hirose, M. 2004.
Projected Augmentation - Augmented Reality using Rotatable Video Projectors. In Proceedings of the 3rd IEEE/ACM international Symposium on Mixed and Augmented Reality (November 02 - 05, 2004). Symposium on Mixed and Augmented Reality. IEEE Computer Society, Washington, DC, 26-35. DOI= http://dx.doi.org/10.1109/ISMAR.2004.47

Arango, M., Bahler, L., Bates, P., Cochinwala, M., Cohrs, D., Fish, R., Gopal, G., Griffeth, N., Herman, G. E., Hickey, T., Lee, K. C., Leland, W. E., Lowery, C., Mak, V., Patterson, J., Ruston, L., Segal, M., Sekar, R. C., Vecchi, M. P., Weinrib, A., and Wuu, S. 1993.
The Touring Machine system. Commun. ACM 36, 1 (Jan. 1993), 69-77. DOI= http://doi.acm.org/10.1145/151233.151239

Gupta, S. and Jaynes, C. 2006.
The universal media book: tracking and augmenting moving surfaces with projected information. In Proceedings of the 2006 Fifth IEEE and ACM international Symposium on Mixed and Augmented Reality (Ismar'06) - Volume 00 (October 22 - 25, 2006). Symposium on Mixed and Augmented Reality. IEEE Computer Society, Washington, DC, 177-180. DOI= http://dx.doi.org/10.1109/ISMAR.2006.297811


Klein, G. and Murray, D. 2007.
Parallel Tracking and Mapping for Small AR Workspaces. In Proceedings of the 2007 6th IEEE and ACM international Symposium on Mixed and Augmented Reality - Volume 00 (November 13 - 16, 2007). Symposium on Mixed and Augmented Reality. IEEE Computer Society, Washington, DC, 1-10. DOI= http://dx.doi.org/10.1109/ISMAR.2007.4538852

Neubert, J., Pretlove, J., and Drummond, T. 2007.
Semi-Autonomous Generation of Appearance-based Edge Models from Image Sequences. In Proceedings of the 2007 6th IEEE and ACM international Symposium on Mixed and Augmented Reality - Volume 00 (November 13 - 16, 2007). Symposium on Mixed and Augmented Reality. IEEE Computer Society, Washington, DC, 1-9. DOI= http://dx.doi.org/10.1109/ISMAR.2007.4538830

posted by maetel