How to weigh an elephant seal with one finger : a simple three-dimensional photogrammetric application

Show simple item record De Bruyn, P.J. Nico Bester, Marthan Nieuwoudt Carlini, Alejandro R. Oosthuizen, Wessel Christiaan 2010-02-01T07:35:09Z 2010-02-01T07:35:09Z 2009-03
dc.description.abstract Several studies have developed photogrammetric techniques for indirect mass estimation of seals. Unfortunately, these techniques are often narrowly delineated for specific field scenarios or species. Many require sophisticated, custom-designed equipment or analytical tools, limiting their applicability. We aimed to devise a photogrammetric technique for accurate volume/mass estimation of seals under a variety of field scenarios without manipulation of the animal and with minimal equipment. We used Photomodeler Pro 3-dimensional modelling software to estimate the mass of 53 weighed southern elephant seals Mirounga leonina. The method is centred on animal volume estimation in relation to the 3-dimensional area around it, rather than features of the animal itself, an approach that liberates limitations associated with earlier studies. No morphometric body measures are required for such volume/mass estimation. We offer predictive equations that allow high confidence in mass estimates relative to measured mass (95% confidence interval of mean deviation from measured mass is from ±1.34 to ±3.83% depending on the field scenario). A single photographer with a measuring stick and non-customised digital photographic equipment can use this technique to determine the mass of an elephant seal anywhere in the field with the push of a button. en
dc.identifier.citation De Bruyn, PJN, Bester, MN, Carlini, AR, Oosthuizen, WC 2009, ‘How to weigh an elephant seal with one finger: a simple three-dimensional photogrammetric application’ Aquatic biology, vol. 5, pp. 31–39. [] en
dc.identifier.issn 1864-7782
dc.identifier.other 10.3354/ab00135
dc.language.iso en en
dc.publisher Inter-Research en
dc.relation.ispartofseries 1864-7782 en
dc.rights Inter-Research. This article is embargoed by the publisher until March 2013. en
dc.subject Mass estimation en
dc.subject Volume estimation en
dc.subject Life history en
dc.subject Phocids en
dc.subject.lcsh Southern elephant seal -- Size en
dc.subject.lcsh Body size en
dc.subject.lcsh Photography en
dc.subject.lcsh Weight (Physics) -- Measurement en
dc.subject.lcsh Photogrammetric pictures en
dc.subject.lcsh Estimation theory -- Computer programs en
dc.title How to weigh an elephant seal with one finger : a simple three-dimensional photogrammetric application en
dc.type Article en

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