<p><strong>Abstract.</strong> Monitoring of cracks and deformation joints of buildings and engineering constructions can be performed effectively using contemporary methods of photogrammetry. Our study allowed us to design the technology for such a monitoring. This technology is adapted for use by building operation and building inspection specialists and does not require special knowledge in photogrammetry. The monitoring equipment includes two blocks of photogrammetric deformation marks, a digital camera and processing software. Each block of deformation marks is designed as a plate of 60 by 40&amp;thinsp;mm size where several dozens of marks are fixed (size of the plate and number of marks may vary). The relative positions of the marks on the plate are determined while block calibration with an accuracy of several microns. While monitoring is performed, two blocks of deformation marks are fixed on both sides of the crack or deformation join. Then marks are photographed. Almost any digital camera is suitable, beginning with smartphone camera and ending with specialized photogrammetric camera. Further processing of collected imagery is performed on the basis of rigorous methods of photogrammetry (specialized software were developed). The processing assumes automatic identification and measurement of marks on digital photographic images with sub-pixel accuracy. Additionally, the photogrammetric calibration and distortion correction are performed for each image. Three-dimensional spatial solution is possible both in the case of single image processing, and in the case of stereopair processing. The dynamics of crack development in three dimensions is determined by the results of several cycles of observations collected over period. Our technology allows to ensure the accuracy of the coordinates and deformations at the level of 0.005&amp;ndash;0.020&amp;thinsp;mm for the photographing distances from 0.1 to 40&amp;thinsp;m.</p>

Abstract. The article presents a simple technological solution PMC (PhotoMicrometer Contrast) for monitoring cracks and deformation joints in buildings and structures. The solution is based on the methods of image processing and photogrammetry. The monitoring equipment includes a special marker, a digital camera and specialized processing software. The marker consists of two thin plastic plates where Aruco marks and special measuring areas are printed. There are two types of markers – for monitoring in one or two directions of crack development. While monitoring is performed, two plates are fixed on both sides of the crack or deformation joint. Then the plates are photographed with a digital camera as often as the observation cycle requires. Any conventional modern digital camera is suitable for photographing after successfully passing the distortion effect test described in the article. Image processing in the software includes automatic identification of the marker in the image, binarization of the image, determination of its scale and dimensions of measuring areas in the current observation cycle. For processing images made at large angles of inclination and rotation, a preliminary solution of the resection in space and the images rectification to the found angles is provided. The dynamics of crack development is determined by the results of several cycles of observations collected over period. Our technology ensures the accuracy of the determination of coordinates and deformations at the level of 0.05 mm and higher for photographing distances from 0.3 to 50 m.