An Application of Close Range Photogrammetry In Dolphin Studies

Bräger, Stefan; Chong, Albert K.

doi:10.1111/0031-868x.00139

Cited by 24 publications

(17 citation statements)

References 9 publications

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“…The distance estimation might be limited due to difficulties of correctly pointing the reticule of the laser range finder on the target. For close range photogrammetry of primates it is important to use more accurate laser range finders together with digital photographs, or alternatively apply stereo-photogrammetry (van Rooij and Videler, 1996;Brä ger and Chong, 1999), use scaling poles (Deschner et al, 2004;Ireland et al, 2006), or a laser-pointer mounted to a lens (Durban and Parson, 2006). Applying photogrammetic methods to measure body length differences in similarly sized individuals Test results for sex differences (MWU) and within-sex variation (ln-transformed data) (F-test).…”

Section: Feasibility Of Digital Photogrammetry and Application To Primentioning

confidence: 99%

Using photogrammetry and color scoring to assess sexual dimorphism in wild western gorillas (Gorilla gorilla)

Breuer

Robbins

Boesch

2007

American J Phys Anthropol

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Investigating sexual dimorphism is important for our understanding of its influence on reproductive strategies including male-male competition, mate choice, and sexual conflict. Measuring physical traits in wild animals can be logistically challenging and disruptive for the animals. Therefore body size and ornament variation in wild primates have rarely been quantified. Gorillas are amongst the most sexually dimorphic and dichromatic primates. Adult males (silverbacks) possess a prominent sagittal crest, a pad of fibrous and fatty tissue on top of the head, have red crest coloration, their saddle appears silver, and they possess a silverline along their stomach. Here we measure levels of sexual dimorphism and within-male variation of body length, head size, and sexual dichromatism in a population of wild western gorillas using photogrammetry. Digital photogrammetry is a useful and precise method to measure sexual dimorphism in physical traits yielding sexual dimorphism indices (ISD), similar to those derived from traditional measurements of skeletal remains. Silverbacks were on an average 1.23 times longer in body length than adult females. Sexual dimorphism of head size was highest in measures of crest size (max ISD: 60.4) compared with measures of facial height (max ISD: 24.7). The most sexually dimorphic head size measures also showed the highest within-sex variation. We found no clear sex differences in crest coloration but there was large sexual dichromatism with high within-male variation in saddle coloration and silverline size. Further studies should examine if these sexually dimorphic traits are honest signals of competitive ability and confer an advantage in reproductive success.

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Section: Feasibility Of Digital Photogrammetry and Application To Primentioning

confidence: 99%

Using photogrammetry and color scoring to assess sexual dimorphism in wild western gorillas (Gorilla gorilla)

Breuer

Robbins

Boesch

2007

American J Phys Anthropol

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“…The use of 3D imaging techniques in underwater applications is increasing, in fields such as the survey of submerged artefacts [1], the monitoring of marine flora and fauna [2,3] or the mapping of large areas [4]. Multi-view 3D reconstruction is gaining popularity in underwater photogrammetry [5], as it requires just an off-the-shelf camera (movie or still) to acquire a sequence of overlapped pictures of the scene under ambient or artificial lighting (passive technique).…”

Section: Introductionmentioning

confidence: 99%

A Comparative Analysis between Active and Passive Techniques for Underwater 3D Reconstruction of Close-Range Objects

Bianco

Gallo

Bruno

et al. 2013

Sensors

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In some application fields, such as underwater archaeology or marine biology, there is the need to collect three-dimensional, close-range data from objects that cannot be removed from their site. In particular, 3D imaging techniques are widely employed for close-range acquisitions in underwater environment. In this work we have compared in water two 3D imaging techniques based on active and passive approaches, respectively, and whole-field acquisition. The comparison is performed under poor visibility conditions, produced in the laboratory by suspending different quantities of clay in a water tank. For a fair comparison, a stereo configuration has been adopted for both the techniques, using the same setup, working distance, calibration, and objects. At the moment, the proposed setup is not suitable for real world applications, but it allowed us to conduct a preliminary analysis on the performances of the two techniques and to understand their capability to acquire 3D points in presence of turbidity. The performances have been evaluated in terms of accuracy and density of the acquired 3D points. Our results can be used as a reference for further comparisons in the analysis of other 3D techniques and algorithms.

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“…For example stereo-photography has been used in situ to measure the recruitment, growth and mortality of coral colonies (Done, 1981), the length of free-swimming sharks (Klimley and Brown, 1983) and dolphins (Brager and Chong, 1999). Stereo-videography has been used for measuring aquacultured salmon (Petrell et al, 1997) and reef fish (Harvey et at., 2001, a, b).…”

Section: Introduction C Onventional Still Photography and Videomentioning

confidence: 99%

A Comparison of the Accuracy and Precision of Measurements from Single and Stereo-Video Systems

Harvey¹,

Shortis²,

Stadler³

et al. 2002

mar technol soc j

100

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Underwater tests using plastic silJwuettes of fish were used to compare the accuracy and precision of measurements made with a single video camera system to tJwse made from two stereo-video systems (one using digital camcorders, the other using Hi8 camcorders). Test measurements made across a variety of ranges and angles ofsilJwuette orientation in thejields of view showed the length estimates from both the digital and HiS stereo-video systems were substantially more accurate and precise than those obtained by the single video camera system, and had the great advantage that the position (range and bearing) and orientation of a fish target could be measured directly. Measurements made with stereo-video were much less restricted by range and subject orientation than those made with singte video. The data resulting from these trials are used to propose a set of guidelines to optimize the accuracy and precision of underwater measurements offish length using single and stereo-video systems. Seager, Department of Geomatics, University of Melbourne, for their contributions to software

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An Application of Close Range Photogrammetry In Dolphin Studies

Cited by 24 publications

References 9 publications

Using photogrammetry and color scoring to assess sexual dimorphism in wild western gorillas (Gorilla gorilla)

Using photogrammetry and color scoring to assess sexual dimorphism in wild western gorillas (Gorilla gorilla)

A Comparative Analysis between Active and Passive Techniques for Underwater 3D Reconstruction of Close-Range Objects

A Comparison of the Accuracy and Precision of Measurements from Single and Stereo-Video Systems

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