VIDEO MEASUREMENT OF LINEAR DISPLACEMENT ALONG AN OBLIQUE LINE USING THE CROSS-RATIO

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  • Mark Colpus
  • Mark Goss-Sampson

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cross-ratio##common.commaListSeparator## camera##common.commaListSeparator## calibration##common.commaListSeparator## perspective

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The purpose of this study was to rediscover the cross-ratio and assess its effectiveness for measuring linear displacement when the image plane is not parallel to the object plane. In the laboratory a fixed, 4m object length was reconstructed with a mean absolute error of 2.6mm (s.d. = 1.6mm, maximum = 4.9mm). In the field, two cameras filmed a fixed, 8m object length with a mean absolute error of 13mm (s.d. = 5mm, maximum = 20mm). The method is very accessible to non-specialists in projective geometry and the results are both valid and reliable.

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2016-05-05

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33 International Conference of Biomechanics in Sports (2015)

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Methodology

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Authors can retain copyright, while granting the International Society of Biomechanics in Sports (ISBS) the right of first publication.