APPLIED 3D PHOTOGRAMMETRIC STUDIES FOR THE HISTORICAL HERITAGE OF EXTREMADURA (SPAIN)

The region of Extremadura, in the southwest of Spain, contains three locations that have been declared UNESCO World Heritage Sites: the Old City of Caceres (1986), the Archeological Ensemble of Merida (1993), and the Royal Monastery of Our Lady of Guadalupe (1993). In the Geomatic Engineering and Urban Heritage Research Group of the University of Extremadura, we are working on a Regional Research Project entitled "Precision three-dimensional modeling, study of structural pathologies and virtual walks through the historical and cultural heritage of Extremadura", in which we create 3D models of some emblematic buildings with regard to which actions are proposed for appropriate conservation and restoration. The procedure used to generate this type of model was in two phases: spatial data capture (topographical information using a TOPCON 7005i) and processing of the spatial information (creation of the 3D model, rectification and processing of the images and virtual recreation). For the work presented in this article, a technique was sought that would make use of very inexpensive techniques, namely a conventional digital camera and a reflectorless Total Station. Obviously, the final result is not the same as if we had used laser scanner digitalization or classical photogrammetry. As indicated in this article, the aqueduct of San Lazaro in Merida and the Plaza de Santa Maria (Cathedral Square) in Caceres were mapped in 3D by means of planes, with a precision of +/- 3 cm. Hence, in addition to making photo-realistic representations, it has been possible to determine the magnitudes (linear dimensions and surface areas) of the pathologies of both monuments (cracks, collapses, damp and deterioration of stonework).