# Review of Image-Based 3D Reconstruction of Building for Automated Construction Progress Monitoring
## 7 Concluding Remarks  
Construction site images, as instant records of the state of the construction site, contain rich information, which makes them natural materials for automatic construction process monitoring. On the one hand, the popularity of built-in camera equipment makes it feasible to obtain massive free images from the construction site. On the other hand, advanced software and hardware technologies provide powerful tools for extracting useful information from daily images. These make the image-based 3D reconstruction more easily accepted by the market, and it will be the main direction of future development. At present, various image-based technologies are isolated from each other, such as image-based modeling, perspective-based method, time-delay photography, and so on. In practice, due to the particularity of the scene, the progress monitoring of a project may re-quire a combination of multiple methods. However, few scholars have broken and reorganized the relevant methods, which makes many methods unable to be fully grafted and used. Therefore, this paper combines the relevant technologies and methods into a comprehensive technology path. In this process, various technologies are separated and then integrated, which makes various technologies connect with each other and provides guidance for technology selection. This is very important for both researchers and engineering practitioners. In addition, in the AEC field, although many methods and technologies have been proposed, the research on image-based construction progress monitoring is still in its infancy. The technology applied to practice is still very few. The knowledge gap and challenges still need to be further explored, such as occlusion, light problems, integration of emerging technologies, etc. Conceptualization, J.X. ; investigation, J.X., X.H. and Y.Z. ; writing--original draft preparation, J.X. ; writing--review and editing, J.X. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Not applicable. Not applicable. Data Availability Statement: Data are contained within the article. The authors declare no conflict of interest. * [PERSON] (2004) [PERSON] Distinctive image features from scale-invariant keypoints. _Int. J. Comput. Vis._**2004**, _60_, 91-110. [CrossRef]
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