Vd 
cite 
ctére 
nages 
le en 
Le de 
conef 
e se 
7). et 
ls de 
[tion 
ar Lo 
nc à 
les 
re 
sion 
nces 
tème 
des 
des 
Les 
  
  
  
A System for Underwater Stereo Video Image Processing 
and Its Application in Fisheries 
R. Lil, T. Curran?, R. Smith2, H. Li! 
Department of Geomatics Engineering, The University of Calgary, Calgary, AB T2N 1N4 
?Institute of Ocean Sciences, Sidney, B.C. V8L 4B2 
Abstract 
Underwater video images are mostly used for visualizing objects in the underwater 
environment. Quantitative analysis, such as measuring objects and reconstruction of 3D 
object shapes, still needs to be researched. In this paper, a system for underwater stereo video 
image preprocessing is presented, which includes modules of Graphical User Interface 
(GUI), preprocessing, camera calibration, photogrammetric processing and graphic display. 
Some geometrical, optical and electrical properties of CCD-camera and images in the 
underwater environment are investigated, for instance, lens distortion, noise 
elimination/reduction, ray bending etc. Based on these, a photogrammetric model can be 
established for determining object space coordinates from measured image coordinates. This 
allows to calculate positions and shapes in the 3D object space as long as the objects to be 
measured can be seen in stereo images. The GUI makes the modules involved transparent to 
users and provides a convenient, efficient and user-friendly environment for object-oriented 
measuring procedures. Results of a water tank test for the camera calibration and fisheries 
applications are presented. Other potential applications of the system could be precise 
seafloor mapping, underwater target tracing, object monitoring and others. 
255