Remote Sensing for structure and infrastructure monitoring: a review.
Alicandro Maria, Sara Zollini, Donatella Dominici, Nicole Pascucci
Inspection and maintenance of structures and infrastructures are, nowadays, hot topics. Extreme weather events and ageing stock, mainly, deteriorate the network infrastructure. Their structural performance should be checked periodically, but this is not always possible, both because of the difficulty to practically carry it out and because, sometimes, insufficient funds are allocated to infrastructure management. In most of the western countries, a highly percentage of bridges, roads, viaducts were built between the 1950s and the 1970s, so the detection plays a fundamental role for their proper functioning. Traditionally, instruments such as levels and total stations have been used to perform high accuracy Structural Health Monitoring (SHM). These can provide highly reliable real-time data on structural condition but, both because of economic reasons and of the difficult-to-access areas, not all the structures and infrastructure can be monitored with traditional techniques. Remote sensing can provide numerous advantages for structures and infrastructures monitoring, because the information can be extracted “from distance” with high reliability and relatively low costs. A comprehensive review on the remote sensing techniques used for structure and infrastructure monitoring is presented in this paper, focusing the attention especially on satellite remote sensing and UAV photogrammetry techniques. Nowadays, SAR (Synthetic Aperture Radar) and optical images are widely used for the aforementioned purpose. From one side, the PSIn-SAR (Permanent Scatterer SAR Interferometry) has been exploited to extract information on ground and infrastructure movements; on the other side, optical images allowed to understand the changes occurred in areas of interest by performing a change detection analysis with different algorithms. UAV photogrammetry outputs have been used for more detailed surveys on specific structures or infrastructures, both to metrically model the objects and, consequently, to detect the degradation phenomena. The main results and consideration obtained by the state of art are discussed and compared and the main advantages and limitations are, finally, outlined in order to provide general achievements within this field.