Reconstruction of Historical Buildings using Structure from Motion (SfM) Applications. An Operational Evaluation and Graphic Analysis

Automatic photogrammetry is based on new theoretical foundations. We must remember that the onset of digital photogrammetry just 30 years ago was entirely manual, and the evaluation of results was only possible in a line format. Subsequently, photo-modelling techniques added the possibility of photo-texturing surfaces using a methodology that was initially manual. Processes were automated in parallel with developments in artificial vision. During the first decade of this century, semiautomatic applications were launched that handled with a high level of automation the two basic phases of a project: namely, the construction of a camera model and its subsequent use. The construction of the model was handled using coded or backlit targets for the identification of orientation points, and the use of these applications was facilitated with techniques of linear correlation using image pairs (as supported by the principles of epipolar geometry) to initially obtain deep recovery or a point cloud model–and then a meshed model or DSM (digital surface model) (Figure 1).