Full text: XVIIIth Congress (Part B5)

  
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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