Geomatic and thermografic techniques for the inspection and diagnosis of historic structures towards their introduction in integrated management systems

Resumo

This research project proposes a novel approach to the integral inspection of historical structures consisting on the conjoint exploitation of the thermographic and the geometric information contained in the images aimed at the quantification of the thermographic inspection through the measurement of areas and lengths. This approach would allow, for example, the measurement of heat lost in a region with an insulation flaw, or the length of a crack in the structure ignored when subjected to visual inspection. The introduction of geometric information in the thermographic survey can be done by resorting to geomatic techniques, either through the application of photogrammetry principles to the thermographic images themselves or through its combination with information acquired through laser scanning. The use of geomatic techniques for the documentation of historic structures is justified by their capacity of representing the as-built reality with accuracy and detail"; while the validity of infrared thermography for the inspection of the as-built condition of any structure has been widely tested by its capacity of detecting both thermal faults such as air infiltrations, thermal bridges or humidity areas, and defects associated to the structure as cracks, voids and delamination. Several methodologies for the integral inspection of historical structures, mainly focused on buildings, using a combination of geomatic and thermographic techniques have been developed and tested in this thesis. The results of the proposed methodologies validate the employment of geomatic techniques as accurate and complete tools for the geometric survey of as-built structures together with the use of infrared thermography for the analysis of their condition state: three approaches for the generation of thermographic 3D models and their associated orthothermograms, or rectified images directly from thermographic images by applying the principles of terrestrial photogrammetry;" one methodology for the fusion of thermographic images with geometric data from a laser scanning point cloud, whose evolution towards automation is also shown in this thesis. Furthermore, a methodology to enable the exploitation of the geometric information available in thermographic images is presented through the design and manufacturing of a special geometric calibration field.