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dc.contributor.authorRío Fernandez, Joaquín del
dc.contributor.authorAguzzi, Jacopo
dc.contributor.authorCosta, C.
dc.contributor.authorMenesatti, Paolo
dc.contributor.authorSbragaglia, Valerio
dc.contributor.authorNogueras Cervera, Marc
dc.contributor.authorSardá Amills, Francesc
dc.contributor.authorManuel Lázaro, Antonio
dc.contributor.otherUniversitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica
dc.identifier.citationDel Rio, J. [et al.]. A new colorimetrically-calibrated automated video-imaging protocol for day-night fish counting at the OBSEA coastal cabled observatory. "Sensors", 30 Octubre 2013, vol. 13, núm. 11, p. 14740-14753.
dc.description.abstractField measurements of the swimming activity rhythms of fishes are scant due to the difficulty of counting individuals at a high frequency over a long period of time. Cabled observatory video monitoring allows such a sampling at a high frequency over unlimited periods of time. Unfortunately, automation for the extraction of biological information (i.e., animals’ visual counts per unit of time) is still a major bottleneck. In this study, we describe a new automated video-imaging protocol for the 24-h continuous counting of fishes in colorimetrically calibrated time-lapse photographic outputs, taken by a shallow water (20 m depth) cabled video-platform, the OBSEA. The spectral reflectance value for each patch was measured between 400 to 700 nm and then converted into standard RGB, used as a reference for all subsequent calibrations. All the images were acquired within a standardized Region Of Interest (ROI), represented by a 2 × 2 m methacrylate panel, endowed with a 9-colour calibration chart, and calibrated using the recently implemented “3D Thin-Plate Spline” warping approach in order to numerically define color by its coordinates in n-dimensional space. That operation was repeated on a subset of images, 500 images as a training set, manually selected since acquired under optimum visibility conditions. All images plus those for the training set were ordered together through Principal Component Analysis allowing the selection of 614 images (67.6%) out of 908 as a total corresponding to 18 days (at 30 min frequency). The Roberts operator (used in image processing and computer vision for edge detection) was used to highlights regions of high spatial colour gradient corresponding to fishes’ bodies. Time series in manual and visual counts were compared together for efficiency evaluation. Periodogram and waveform analysis outputs provided very similar results, although quantified parameters in relation to the strength of respective rhythms were different. Results indicate that automation efficiency is limited by optimum visibility conditions. Data sets from manual counting present the larger day-night fluctuations in comparison to those derived from automation. This comparison indicates that the automation protocol subestimate fish numbers but it is anyway suitable for the study of community activity rhythms.
dc.format.extent14 p.
dc.rightsAttribution 3.0 Spain
dc.subjectÀrees temàtiques de la UPC::Enginyeria de la telecomunicació::Processament del senyal::Processament de la imatge i del senyal vídeo
dc.subjectÀrees temàtiques de la UPC::Enginyeria agroalimentària::Ciències de la terra i de la vida::Biologia
dc.subject.lcshUnderwater imaging systems
dc.subject.lcshFish populations -- Mediterranean Sea
dc.subject.lcshBiological rhythms
dc.subject.lcshMarine species diversity
dc.subject.lcshBiodiversity research
dc.subject.lcshOcean bottom--Research
dc.subject.lcshColorimetry--Data processing
dc.subject.otherCoastal fishes
dc.subject.otherCables observatories
dc.subject.otherAutomated video-imaging
dc.subject.otherColorimetric calibration
dc.subject.otherSwimming rhythms
dc.subject.other3D Thin-Plate Spline warping
dc.titleA new colorimetrically-calibrated automated video-imaging protocol for day-night fish counting at the OBSEA coastal cabled observatory
dc.subject.lemacComunicacions subacuàtiques
dc.subject.lemacEcosistemes marins
dc.subject.lemacFons marins -- Investigació
dc.subject.lemacColorimetria -- Aplicacions científiques
dc.contributor.groupUniversitat Politècnica de Catalunya. SARTI - Centre de Desenvolupament Tecnològic de Sistemes d'Adquisició Remota i Tractament de la Informació
dc.description.peerreviewedPeer Reviewed
dc.rights.accessOpen Access
dc.description.versionPostprint (published version)
dc.relation.projectidinfo:eu-repo/grantAgreement/EC/FP7/211816/EU/European Multidisciplinary Seafloor Observation/EMSO
local.citation.authorDel Rio, J.; Aguzzi, J.; Costa, C.; Menesatti, P.; Sbragaglia, V.; Nogueras, M.; Sarda, F.; Manuel, A.

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Attribution 3.0 Spain
Except where otherwise noted, content on this work is licensed under a Creative Commons license : Attribution 3.0 Spain