Abstract: A method and apparatus for the generation of a three-dimensional image representing structures detected within a volume. Two dimensional differential phase measurements are made on backscatter signals. Azimuth, elevation and range are calculated over a statistically large number of spatially diverse backscatter returns and used to construct a histogram of backscatter data. The histogram of backscatter data can be processed with standard image processing techniques to produce terrain maps or volumetric models of the volume of water. A system constructed according to the methods of this invention is capable of producing a three-dimensional map of the volume insonified without mechanical array scanning or electronic beam scanning. A combination of two or more volumetric scanning systems can be used to increase the resolution achievable in modelling the volumetric area.