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: 180-196. doi:10.1111/j.1477-9730.2010.00578.x

Author Chong, Albert K.
Brownstein, Gretchen
Title A technique for improving webcam precision in biological plant measurement
Journal name Photogrammetric Record   Check publisher's open access policy
ISSN 0031-868X
Publication date 2010-06
Sub-type Article (original research)
DOI 10.1111/j.1477-9730.2010.00578.x
Open Access Status
Volume 25
Issue 130
Start page 180
End page 196
Total pages 17
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Language eng
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 0·3±0·2 and 1·7±0·4-mm was achieved, depending on the type of grass observed and the digitising technique used.
Keyword Ambient temperature
Biological plant
Camera self-calibration
In-situ principal distance determination
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Mined Land Rehabilitation Publications
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Created: Tue, 12 Nov 2013, 08:12:09 EST by Gretchen Brownstein on behalf of Centre For Mined Land Rehabilitation