Multibeam sonar image processing and three‐dimensional analysis of fish schools

1998 ◽  
Vol 103 (5) ◽  
pp. 2939-2939 ◽  
Author(s):  
Chafiaa Hamitouche ◽  
Valerie Fracasso ◽  
Carla Scalabrin
Keyword(s):  
Image Processing ◽  
Dimensional Analysis ◽  
Three Dimensional ◽  
Multibeam Sonar ◽  
Fish Schools ◽  
Sonar Image

Three-dimensional analysis of alveolar bone resorption by image processing of 3-D dental CT images

2006 ◽  
Author(s):  
Jiro Nagao ◽  
Takayuki Kitasaka ◽  
Kensaku Mori ◽  
Yasuhito Suenaga ◽  
Shohzoh Yamada ◽  
...  
Keyword(s):  
Image Processing ◽  
Bone Resorption ◽  
Dimensional Analysis ◽  
Alveolar Bone ◽  
Three Dimensional ◽  
Ct Images ◽  
Dental Ct

scholarly journals An operational system for automatic school identification on multibeam sonar echoes

2009 ◽  
Vol 66 (5) ◽  
pp. 935-949 ◽  
Author(s):  
Vasilis Trygonis ◽  
Stratis Georgakarakos ◽  
E. John Simmonds
Keyword(s):  
Three Dimensional ◽  
Beam Width ◽  
Multibeam Sonar ◽  
Operational System ◽  
Fish Schools ◽  
Fish School ◽  
School Identification ◽  
Detection And Identification ◽  
Spatio Temporal ◽  
Sonar Echoes

Abstract Trygonis, V., Georgakarakos, S., and Simmonds, E. J. 2009. An operational system for automatic school identification on multibeam sonar echoes. – ICES Journal of Marine Science, 66: 935–949. A system for identifying and tracking fish schools is demonstrated, based on the analysis of multibeam sonar data obtained by a Simrad SP90 long-range sonar. Fish-school detection and identification techniques are similar to those commonly used for vertical echosounders, further enhanced with innovative processing algorithms applied to successive multibeam echograms, increasing the certainty that the identified objects are fish schools. Additionally, analysis of school dynamic parameters facilitates the classification of targets into certain groups, here discriminating the fish aggregating device-natant fish complex from tuna. Statistical analysis of selected tracks quantifies the spatio-temporal variability of the school descriptors, which are used retrospectively to select appropriate analysis thresholds. The algorithms are implemented in an acquisition, visualization, and processing software platform that is flexible regarding sonar characteristics (beam width and number of beams) and can be extended easily to track school echotraces in a three-dimensional mode.

From two dimensions to three: the use of multibeam sonar for a new approach in fisheries acoustics

1999 ◽  
Vol 56 (1) ◽  
pp. 6-12 ◽  
Author(s):  
François Gerlotto ◽  
Marc Soria ◽  
Pierre Fréon
Keyword(s):  
Three Dimensional ◽  
Two Dimensions ◽  
School Structure ◽  
Fish Behaviour ◽  
New Approach ◽  
Multibeam Sonar ◽  
Fish Schools ◽  
Fisheries Acoustics ◽  
Working Frequency ◽  
School Classification

We present a methodology applying multibeam sonar for three-dimensional (3D) observation of fish schools that enhances the conventional use of vertical scientific echo sounders. The sonar we employ has 60 beams of 1.5° each. Its working frequency is 455 kHz. It is applied on a vertical plan normal to the vessel route, observing from the surface line to the bottom with a range set to 100 m. The sampled volume is 14 times larger than the volume observed with vertical echo sounding. The contribution of this new methodology to fisheries acoustics is detailed for school classification, internal school structure, spatial distribution of schools, fish behaviour, and biomass estimates. For each of these points, we present some preliminary results with the aim of defining the real progress in fisheries acoustics research as a result of 3D acoustics. Finally, we present a list of technical and methodological improvements that we are developing in order to make multibeam sonar fully adapted to fisheries acoustics.

scholarly journals Validating two-dimensional leadership models on three-dimensionally structured fish schools

2017 ◽  
Vol 4 (1) ◽  
pp. 160804 ◽  
Author(s):  
Isobel Watts ◽  
Máté Nagy ◽  
Robert I. Holbrook ◽  
Dora Biro ◽  
Theresa Burt de Perera
Keyword(s):  
Dimensional Analysis ◽  
Three Dimensional ◽  
Interaction Networks ◽  
Three Dimensions ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
Fish Schools ◽  
Astyanax Mexicanus ◽  
Pairwise Interactions ◽  
The Individual

Identifying leader–follower interactions is crucial for understanding how a group decides where or when to move, and how this information is transferred between members. Although many animal groups have a three-dimensional structure, previous studies investigating leader–follower interactions have often ignored vertical information. This raises the question of whether commonly used two-dimensional leader–follower analyses can be used justifiably on groups that interact in three dimensions. To address this, we quantified the individual movements of banded tetra fish ( Astyanax mexicanus ) within shoals by computing the three-dimensional trajectories of all individuals using a stereo-camera technique. We used these data firstly to identify and compare leader–follower interactions in two and three dimensions, and secondly to analyse leadership with respect to an individual's spatial position in three dimensions. We show that for 95% of all pairwise interactions leadership identified through two-dimensional analysis matches that identified through three-dimensional analysis, and we reveal that fish attend to the same shoalmates for vertical information as they do for horizontal information. Our results therefore highlight that three-dimensional analyses are not always required to identify leader–follower relationships in species that move freely in three dimensions. We discuss our results in terms of the importance of taking species' sensory capacities into account when studying interaction networks within groups.

In situ investigation of the primary recrystallization of alpha titanium in HVEM

1978 ◽  
Vol 36 (1) ◽  
pp. 634-635
Author(s):  
S. Naka ◽  
R. Penelle ◽  
R. Valle
Keyword(s):  
Dimensional Analysis ◽  
Texture Evolution ◽  
Cold Work ◽  
Three Dimensional ◽  
Primary Recrystallization ◽  
Thin Foils ◽  
In Situ Investigation ◽  
Grain Growth Model ◽  
Alpha Titanium

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.

EMCAT: An automatic image-processing system for electron-microscopic tomography

1994 ◽  
Vol 52 ◽  
pp. 418-419
Author(s):  
Weiping Liu ◽  
John W. Sedat ◽  
David A. Agard
Keyword(s):  
Image Processing ◽  
Structural Information ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Processing System ◽  
Electron Microscopic ◽  
Data Set ◽  
Ordered Structures ◽  
Automatic Image Processing ◽  
Em Tomography

Any real world object is three-dimensional. The principle of tomography, which reconstructs the 3-D structure of an object from its 2-D projections of different view angles has found application in many disciplines. Electron Microscopic (EM) tomography on non-ordered structures (e.g., subcellular structures in biology and non-crystalline structures in material science) has been exercised sporadically in the last twenty years or so. As vital as is the 3-D structural information and with no existing alternative 3-D imaging technique to compete in its high resolution range, the technique to date remains the kingdom of a brave few. Its tedious tasks have been preventing it from being a routine tool. One keyword in promoting its popularity is automation: The data collection has been automated in our lab, which can routinely yield a data set of over 100 projections in the matter of a few hours. Now the image processing part is also automated. Such automations finish the job easier, faster and better.

Sign in / Sign up

Export Citation Format

Share Document