A technique for improving webcam precision in biological plant measurement

Chong, Albert K. and Brownstein, Gretchen (2010) A technique for improving webcam precision in biological plant measurement. Photogrammetric Record, 25 (130). pp. 180-196. ISSN 0031-868X

Abstract

In an attempt to harness webcam technology for the biological monitoring of grassland plants, a Microsoft LifeCam-based photogrammetric system was developed for the remote capture of 3D measurements of plants. Research was necessary to determine the metric quality of this webcam imagery for photogrammetric 3D measurement. This paper presents the details of a qualitative evaluation of a LifeCam VX-3000 for indoor and outdoor photogrammetric measurement together with the results of a case study involving two common small grassland plants. In the evaluation, laboratory and in-situ principal distance (PD) determination techniques were performed, thus evaluating the significance of the latter for improving measurement accuracy in an uncontrolled environment despite the ineffective focusing of this imaging sensor. The effect of outdoor ambient temperature on the PD was investigated. Results show that sharp focusing is a problem with this webcam, as shown by the disparity of the laboratory-determined PD of various object distances. However, the determination of the PD using field images improves the measurement accuracy. Using this approach, 3D measurement accuracy of between 0Æ3±0Æ2 and 1Æ7±0Æ4mm was achieved, depending on the type of grass observed and the digitising technique used.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Copyright of Photogrammetric Record is the property of Blackwell Publishing Limited and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Depositing User: Dr Albert Kon-Fook Chong
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Surveying and Land Information
Date Deposited: 13 Feb 2011 09:54
Last Modified: 03 Jul 2013 00:29
Uncontrolled Keywords: ambient temperature; biological plant; camera self-calibration; in-situ principal distance determination; webcam
Fields of Research (FOR2008): 10 Technology > 1099 Other Technology > 109999 Technology not elsewhere classified
08 Information and Computing Sciences > 0801 Artificial Intelligence and Image Processing > 080106 Image Processing
05 Environmental Sciences > 0502 Environmental Science and Management > 050206 Environmental Monitoring
Socio-Economic Objective (SEO2008): D Environment > 96 Environment > 9608 Flora, Fauna and Biodiversity > 960803 Documentation of Undescribed Flora and Fauna
Identification Number or DOI: doi: 10.1111/j.1477-9730.2010.00578.x
URI: http://eprints.usq.edu.au/id/eprint/18328

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