IMPROVEMENT OF FISHFARM PEN DESIGN USING COMPUTATIONAL STRUCTURAL MODELLING AND
LARGE-SCALE UNDERWATER PHOTOGRAMMETRY (COSMOLUP)
Heinrich Schewe, technet GmbH, Königstr 53, D-78628 Rottweil
Erik Moncrieff, technet GmbH, MaaRenstr.14, D-10777 Berlin
Prof. Dr.-Ing. Lothar Grundig, Institut fur Geodasie und Photogrammetrie, Technische Universitat Berlin
Comission V, Working Group 3
KEY WORDS: Digital, Close Range, Underwater, CCD, Bundle, Calibration, Reconstruction
ABSTRACT
The paper presents first results of an ongoing collaborative CRAFT action under the European Union's BRITE/EURAM
programme. The aim of the presented research programme is to improve the structural performance of the net systems
used in fishfarm pens. In particular, it is hoped that the level of pen volume loss due to current can be reduced, as well
as improving resistance to sea mammal predation. Both these goals will be of significant economic benefit to the entire
European fishfarming industry. A key element of the project is the measurement system for determining the underwater
3D geometry of the pen nets. A underwater CCD camera system and the photogrammetric software package PICTRAN
are used. The various topics and special problems of underwater photogrammetry such as hardware choice, camera
calibration, and working procedures are described. The project is being executed in a series of sequential stages;
evaluation of the functionality and suitability of the components, and acquisition of geometrical data for the actual
computational modelling calibration and design improvement in the final stage. The statical analysis suite of the EASY
lightweight structure design system is being used for the computational modelling.
KURZFASSUNG
Erste Ergebnisse eines laufenden CRAFT-Projektes der Europaischen Union werden prasentiert. Das Ziel dieses Pro-
jektes ist es, die Netzsysteme fur Fischfarmgehege zu verbessern. Insbesondere soll der Volumenverlust der Käfige
aufgrund von Strömung reduziert und der Schutz vor Meeressäugern verbessert weden. Beide Ziele bedeuten entspre-
chenden wirtschaftlichen Nutzen für die gesamte europäische Fischfarmindustrie. Wichtiger Bestandteil des Projektes
ist die Erfassung der Netzgeometrie unter Wasser. Hierfür wird eine CCD-Unterwasserkamera und das Photogramme-
triesystem PICTRAN eingesetzt. Spezielle Probleme der Unterwasserphotogrammetrie wie Spezialhardware, Kalibrie-
rung und Vorgehensweise werden angesprochen. Das Projekt wird in mehreren Stufen durchgeführt, wobei zunächst
Funktionsfähigkeit und Eignung untersucht werden und erst im letzten Schritt die Geometriedaten für die computerge-
stützte Modellierung und Designverbesserungen gewonnen werden. Die rechnerische Modellierung wird mit Hilfe der
statischen Analyse des Programmsystems EASY zum Design von Flächentragwerken durchgeführt.
1 BACKGROUND INFORMATION e To develop and calibrate a non-linear computational
model capable of predicting the structural behaviour
1.1 Objectives and expected results of pen systems.
The ultimate aim of the research programme is to im- © To propose modifications to existing pen designs
prove the structural performance of the net systems used which improve structural and economic perform-
in fishfarm pens. Given the comparative lack of scientific ance.
research directed at this problem, significant improve-
ments can be expected. In particular, it is hoped that the
level of pen volume loss due to current can be reduced,
as well as improving resistance to sea mammal preda-
tion. Both these goals will be of significant economic
benefit to the entire European fishfarming industry.
e To propose completely novel pen systems with im-
proved structural and economic performance.
1.2 Economic and Industrial Benefits
Over the past decade, the development of fish farming in
Europe has been spectacular. In particular the north-west
of Scotland, Shetland and Ireland have experienced very
large levels of investment in salmon farms. The Euro-
pean industry is, however, not restricted to Atlantic
salmon and extends to the commercial cultivation of
species such as trout, bream and sea bass in areas in-
cluding the Aegean. Experimental farming of fish such as
e To measure underwater cage net geometry using 3D halibut is also currently being investigated.
photogrammetric reconstruction.
A main part is the measurement system for determining
the underwater 3D geometry of the pen nets. The photo-
grammetric system PICTRAN is used, which reconstructs
the 3D data from multiple 2D images.
The specific project goals are,
At present the salmon industry is experiencing a period of
slump due to short term overproduction causing low
524
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
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