A program to compute geographical positions of underwater artifact based on linear measurements

Abstract

While carrying out underwater positioning in shallow waters, the Diver Archaeologists measure lengths and bearings from a base line of the well-established control network to each and every corner of the artifact. A program in Basic language (GWBASIC) is presented in this technical report, which can compute the geographical positions of all the comers of the submerged artifact, based on the underwater range measurements. The main advantage of using this program is that it requires only linear measurements thereby eliminating the uphill task of measuring bearings and azimuth between the comers, using an underwater compass. The three dimensional output (X, Y, Z) derived from this program would be of great use to marine archaeologists to represent the submerged artifact in three dimensions (3-D view), in its true form with greater speed and accuracy than the normal method, while making the maps. The output being in digital form with geographical co-ordinates, using either GIS (Geographic Information System) or any hydrographic post processing software, excellent site plans and other related maps can be prepared on any convenient scale. This user friendly program enables the marine archaeologists to process their field measurements much faster and easier with geographical co-ordinates than the manual method of plotting the comers of the artifact, which were often on plain rectangular co-ordinates. As the final maps are prepared in geographical grid, they can be directly super imposed on hydrographic charts of the same scale, to get quick idea about the location of the survey area, the depth contours in that area, etc. for further studies