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  • 1
    Electronic Resource
    Electronic Resource
    Assisting Manual Dolphin Identification by Computer Extraction of Dorsal Ratio (1999)
    Springer
    Annals of biomedical engineering 27 (1999), S. 830-838 
    Details
    ISSN: 1573-9686
    Keywords: Photoidentification ; Image database ; Feature extraction ; Curve representation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Marine biologists use a measurement called the “Dorsal Ratio” in the process of manual identification of bottlenose dolphins. The dorsal ratio denotes the relative distances of the two largest notches from the tip on the dorsal fin. The manual computation of this ratio is time consuming, labor intensive, and user dependent. This paper presents a computer-assisted system to extract the dorsal ratio for use in identification of individual animals. The first component of the system consists of active contour modeling where the trailing edge of the dorsal fin is detected. This is followed by a curvature module to find the characteristic fin points: tip and two most prominent notches. Curvature smoothing is performed at various smoothing scales, and wavelet coefficients are utilized to select an appropriate smoothing scale. The dorsal ratio is then computed from the curvature function at the appropriate smoothing scale. The system was tested using 296 digitized images of dolphins, representing 94 individual dolphins. The results obtained indicate that the computer extracted dorsal ratio can be used in place of the manually extracted dorsal ratio as part of the manual identification process. © 1999 Biomedical Engineering Society. PAC99: 8718Bb, 4230Va
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.235
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  • 2
    Electronic Resource
    Electronic Resource
    A String Matching Computer-Assisted System for Dolphin Photoidentification (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 1269-1279 
    Details
    ISSN: 1573-9686
    Keywords: Dolphin photographic identification ; Computer-assisted system ; Dorsal fin curvature representation ; Syntactic/semantic curve modeling ; String matching ; Dolphin image database
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract This paper presents a syntactic/semantic string representation scheme as well as a string matching method as part of a computer-assisted system to identify dolphins from photographs of their dorsal fins. A low-level string representation is constructed from the curvature function of a dolphin's fin trailing edge, consisting of positive and negative curvature primitives. A high-level string representation is then built over the low-level string via merging appropriate groupings of primitives in order to have a less sensitive representation to curvature fluctuations or noise. A family of syntactic/semantic distance measures between two strings is introduced. A composite distance measure is then defined and used as a dissimilarity measure for database search, highlighting both the syntax (structure or sequence) and semantic (attribute or feature) differences. The syntax consists of an ordered sequence of significant protrusions and intrusions on the edge, while the semantics consist of seven attributes extracted from the edge and its curvature function. The matching results are reported for a database of 624 images corresponding to 164 individual dolphins. The identification results indicate that the developed string matching method performs better than the previous matching methods including dorsal ratio, curvature, and curve matching. The developed computer-assisted system can help marine mammalogists in their identification of dolphins, since it allows them to examine only a handful of candidate images instead of the currently used manual searching of the entire database. © 2000 Biomedical Engineering Society. PAC00: 8780Tq, 4230Sy, 0705Pj
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.1317532
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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