VRML visualization of pelagic fish movement in the echosounder beam

During over thirty years of development of echosounders, the acquisition software has developed different kind of charts for data visualization. In the paper the concept of creation of dynamic echograms from the data acquired in acoustical surveys is presented. As the modern split-beam echosounders allow for nonambiguous localization of targets in the water column, it is possible to visualize them in 3D coordinate system. Virtual Reality Modeling Language VRML is a popular language used in modeling of virtual reality. Using its build-in properties, it is relatively easy to visualize movement of fish treated as an object in any coordinate system. VRML despite the typical application in computer graphics is also used in other various fields. For instance in chemistry it is used for visualization of atom particles, in medicine for modeling of human organs, in astronomy for visualization of trajectories of the stars and in geography and navigation for creation of 3D maps. Hence, in this paper we describe its application in fisheries. Additionally, as the any WWW browser can be equipped with VRML plugin 3D fish visualization can be redistributed in the Internet.