Triangulation methods in engineering measurement
Industrial surveying and photogrammetry are being increasingly applied to the measurement of engineering objects which have typical dimensions in the range 2-100 metres. Both techniques are examples of the principle of triangulation. By applying photocrammetric concepts to surveying methods and vice-versa, a general approach is established which has a number of advantages. In particular. alternative strategies for constructing and analysing measurement networks are developed. These should help to strengthen the geometry and simplify the analysis. The primary results concern the use of non-levelled theodolites, which have applications on board floating objects, and three new suggestions for controlling and computing relative orientations in photogrammetry. These involve reciprocal observations with theodolites. the photographing of linear scales defined by three target points and employing cameras which have been levelled. As a secondary result, some consideration Is given to automation, and instrument design. It is suggested that polarimetry could be successfully applied to improve the transfer of orientation in confined situations, such as in mining. In addition, the potential use of electronic cameras as photo-theodolites is discussed.