Surface Reconstruction of Maltese Cisterns Using ROV Sonar Data for Archeological Study

We present a methodology and algorithm for the reconstruc­ tion of three dimensional geometric models of ancient Maltese water stor­ age systems, i.e. cisterns, from sonar data. This project was conducted as a part of a four week expedition on the islands of Malta and Gozo. During this expedition, investigators used underwater robot systems ca­ pable of mapping ancient underwater cisterns and tunnels. The mapping included probabilistic algorithms for constructing the maps of the sonar data and computer graphics for surface reconstruction and visualization. This paper presents the general methodology for the data acquisition and the novel application of algorithms from computer graphics for surface reconstruction to this new data setting. In addition to reconstructing the geometry of the cisterns, the visualization system includes methods to enhance the understanding of the data by visualizing water level and texture detail either through the application of real image data via pro­ jective textures or by more standard texture mapping techniques. The resulting surface reconstructions and visualizations can be used by ar­ chaeologists for educational purposes and to help understand the shape and history of such water receptacles.