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Proceedings Paper

Scale artifact length dependence of videogrammetry system uncertainty
Author(s): Scott C. Sandwith
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Paper Abstract

Testing has shown significant dependence between the length of the scale artifact and the achievable system uncertainty for high accuracy industrial videogrammetry on high aspect ratio objects. Shop practice traditionally allows scale artifacts under 1/5 the object length. This practice can lead to higher than expected uncertainties because the uncertainty of the metric defining the physical scale must be multiplied by the ratio of object length to scale artifact length. This relationship is incorporated into the U95 uncertainty relationship. Test cases validating the uncertainty model are also presented. A network of scale reference points can also be integrated on an object using a laser tracking interferometer. Testing results show a significant reduction in total uncertainties when using this network to define the scale for videogrammetry applications. Measuring a 500-inch (12.7 meters) object and scaling the survey with a 130-inch (3.3 meters), scale bar produced an uncertainty of 22-ppm. When the 500-inch object survey was scaled with laser tracker data, the system yielded an uncertainty of 9-ppm.

Paper Details

Date Published: 10 December 1997
PDF: 12 pages
Proc. SPIE 3204, Three-Dimensional Imaging and Laser-based Systems for Metrology and Inspection III, (10 December 1997); doi: 10.1117/12.294464
Show Author Affiliations
Scott C. Sandwith, Boeing Commercial Airplane Group (United States)

Published in SPIE Proceedings Vol. 3204:
Three-Dimensional Imaging and Laser-based Systems for Metrology and Inspection III
Kevin G. Harding; Donald J. Svetkoff, Editor(s)

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