Point clouds and orthomosaics from photographs their use in a Civil Engineering Laboratory

Abstract

Generating point clouds or orthomosaics from photographs can be a very affordable and easy way of access to valuable information of an object or a surface. Close range photographs, good acquisition geometry, allows that one can achieve high quality point clouds and othomosaics, sometimes reaching sub-millimetre accuracy. The authors of this paper, the three working in the National Laboratory for Civil Engineering of Portugal, are identifying within the Laboratory, applications where point clouds and orthomosaics can be useful to studies performed by their colleagues, being that this paper presents the first results. The “objects” that were under study, and here presented, are: a sample of a rock joint, where the point clouds will help to characterize the surface roughness and the orthomosaic will support the studies or the variation of the colour of the surface of the specimen during shear tests; a scaled model of a breakwater, where point clouds will be used to support the evaluation of the stability of the structure to the impact of waves; walls of concrete dams, as a support to visual inspections; a timber beam under stress, where photos can be used to measure the displacements.