IRT-photogrammetry procedure fro 3D rendering

The combination of terrestrial laser scanner survey, photogrammetric imagery and IRT allows the generation of 3D multispectral models useful for localization, visualization, and analysis of anomalies in buildings. The proposal of research focuses on the emerging need of more effective images for gathering the thermal anomalies where the geometry of the object strongly affects the thermal behaviour. Such conditions can be due to reflecting materials, non planar surfaces, geometrical pattern of surface decoration and finishing, partial shadows, reflection effects due to fixed objects close to the surface which are under investigation, and places where movement is restricted for data acquisition.A more rigorous approach to obtain a 3D rendering of a complex building is based on the use of photogrammetric ortho-projection. This requires a 3D model of the surface to be mapped and a coverage of the images to be projectec. Different kinds of data can be used to this purpose with different results (RGB, IRT, near-infrared images). 3D models can be obtained from different sources: existing drawings and projects, photogrammetric or terrestrial laser scanning surveying (see Alba et al. 2011). An alternative procedure based on the use of a ‘bi-camera’ system integrating an RGB and an IRT camera is proposed in Alba et al. (2011). This exploits the possibility of using the RGB images for easier registration. At the current state-of-art, no solution seems to show an overwhelming potentials, but the best option has to be sought for each practical case. However, good results can be obtained by using these approaches in the case of buildings showing not too much complex surfaces.