New Measurement Methods for Structure Deformation and Objects Exact Dimension Determination

Abstract

The current rapid development of technologies enables new procedures for deformation and the detecting of construction defects and their modelling and monitoring in BIM. New instruments were developed for fast and sufficiently accurate mapping like personal mobile laser scanners (PLS). In the world of photography, the size of camera sensors is bigger, and the photographs are sharper. The rapid development of computer performance enables automatic and complex calculations, which lead to large sets of detailed 3D data and a high degree of automation. This influences photogrammetry and its methods. The results are more detailed and more accurate. Deformation, defects and exact dimensions (metrology) of different structures or objects can be currently measured by digital close-range photogrammetry. Cracks and cavities are monitored for structure status detection. This is important for planning reconstruction and for financial reasons. For structures like cooling towers, chimneys, or bridges can be created on a 3D model with a high texture resolution for finding and monitoring cracks and cavities. Deformations or defects that were found must be in scale, and measurable for the calculation of the scope of repair work and its price. The generated 3D object model can then be used for further measurements, for the price estimation of renovation, and for the creation of a BIM, in which all processes can be modelled and watched. Deformation can be monitored over time by creating additional models after a defined period. Captured 3D models from different periods can be compared in software like CloudCompare to determine the progress of degradational changes. The trend of the aging of the structure can be traced, which will be helpful for the reasonable planning of reconstruction. Based on the rapid development and miniaturization of measuring devices, new, smaller, easier to use, and more perfect devices are constructed. This also applies to the new group of laser scanners constructed for basic measurement and structure modeling for BIM. Conventional laser scanners can be accurate, but they are relatively large and heavy, difficult to transport and measuring with them is relatively slow (stop and go type). If the project goal is the classic construction, documentation of the object, data transfer to BIM or basic documentation of objects, PLS is the ideal device. Thanks to the development of accurate IMU (inertial measurement unit) and SLAM (simultaneous localization and mapping) technologies, these devices are on the rise. The forthcoming article will inform about the methods of accurate close-range photogrammetry and mobile laser scanning and will show their advantages with specific examples.