The application of real time 3D acoustical imaging

The advent of real time 3D acoustical imaging makes entirely new sensing capabilities available to the ocean community. This paper presents the fundamentals of this new technique and explains the differences between this method and conventional type imaging methods like video and sonar. 3D real time acoustical imaging is characterized by a number of important features like the ability to image a moving object, image presentation in a 3D environment, extraction of x,y,z coordinates, the possibility of adding virtual objects to the 3D scene as well as imaging in turbid water with practically zero visibility. 3D real time acoustics generate an “acoustic movie” with an update rate of between 2 and 10 images per second. Hence an object moving in any direction can be shown real time. All acoustic 3D data are known with respect to reflection intensity and x,y and z co-ordinates and can thus be shown in a 3D environment, i.e. the observer can change observation point in the 3D scene in order to acquire the best possible information. Moreover, knowledge of the 3D geometry allows for extraction of x,y,z co-ordinates for any pixel in the 3D image. Size and distance data are thus easy to obtain. The 3D presentation method allows for addition of virtual objects in the scene. The virtual objects can be described in VRML-format. The detection range of acoustical imaging systems extends to at least 100 metres, a range that exceeds the capabilities of any optical system. Also, even in near zero visibility environments, an acoustical system will generate images