Documentation of Nantou City Wall in Shenzhen by Digital Close Range Photogrammetry and Surface Fitting

Traditional architectonic heritage elements are fragile and irreplaceable resources, signs of the ancient ways of life and the history of the modern societies, and essential valuable elements of the own landscape of a region. Accurate updated documentation might be the basis for any conservation or restoration intervention over architectonic heritage in order to ensure the conservation in its original appearance and in a collapse risk-free state, with the minimum intervention. The paper deals with the conservation of Nantou city wall. Close-range photogrammetry are proposed as a preventive method which allows to measure the city wall. The photos have been referred to each other, and then precise coordinates of control points on the city wall have been measured. After analysis of the coordinates we find the situation of the wall surface which deviated from the original two-dimensional plane. Then finite element model was generated and structural analysis has been finished.