dc.contributor.author |
De Bruyn, P.J. Nico
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dc.contributor.author |
Bester, Marthan Nieuwoudt
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dc.contributor.author |
Carlini, Alejandro R.
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dc.contributor.author |
Oosthuizen, Wessel Christiaan
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dc.date.accessioned |
2010-02-01T07:35:09Z |
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dc.date.available |
2010-02-01T07:35:09Z |
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dc.date.issued |
2009-03 |
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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. |
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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. [http://www.int-res.com/journals/ab] |
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dc.identifier.issn |
1864-7782 |
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dc.identifier.other |
10.3354/ab00135 |
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dc.identifier.uri |
http://hdl.handle.net/2263/12817 |
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dc.language.iso |
en |
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dc.publisher |
Inter-Research |
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dc.relation.ispartofseries |
1864-7782 |
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dc.rights |
Inter-Research. This article is embargoed by the publisher until March 2013. |
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dc.subject |
Mass estimation |
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dc.subject |
Volume estimation |
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dc.subject |
Life history |
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dc.subject |
Phocids |
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dc.subject.lcsh |
Southern elephant seal -- Size |
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dc.subject.lcsh |
Body size |
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dc.subject.lcsh |
Photography |
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dc.subject.lcsh |
Weight (Physics) -- Measurement |
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dc.subject.lcsh |
Photogrammetric pictures |
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dc.subject.lcsh |
Estimation theory -- Computer programs |
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dc.title |
How to weigh an elephant seal with one finger : a simple three-dimensional photogrammetric application |
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dc.type |
Article |
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