# Automated Data Acquisition in Construction with Remote Sensing Technologies
## 4 Integration of Various RS Technologies
### Integration of the Vision-Based Technologies Together and with Other RTLS
#### 4.3.1 Photogrammetry Integration with Laser Scanning  
Due to the computational complexity of photogrammetric surveying, construction management researchers have attempted to decrease the number of required photos by imposing geometric constraints and automating the modeling process based on pattern recognition and feature detection [7]. Moreover, a solution based on the integration of the photogrammetry data with the data acquired by a 3D laser scanner is also investigated aiming to reduce the effort required for 3D modeling [25]. In fact, due to the geometric stability of digital images, they are very suitable references for inspection \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Method**} & **Data Acquisition** & **Processing** & \multirow{2}{*}{**Affordability**} & **Data Accuracy** & \multirow{2}{*}{**Scalability**} \\  & **Effort** & **Time** & & & **and Reliability** & \\ \hline Photogrammetry & \(\surd\) & \(\surd\surd\) & \(\surd\surd\) & \(\surd\) & \(\surd\) \\ \hline Laser scanning & \(\surd\surd\) & \(\surd\surd\surd\) & \(\surd\) & \(\surd\surd\) & \(\surd\surd\) \\ \hline Photogrammetry + laser scanning & \(\surd\) & \(\surd\surd\) & \(\surd\surd\) & \(\surd\surd\) & \(\surd\surd\) \\ \hline Photogrammetry + RTS & \(\surd\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\surd\) \\ \hline Photogrammetry + UWB & \(\surd\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\surd\surd\) \\ \hline Laser scanning + RFID & \(\surd\) & \(\surd\surd\) & \(\surd\) & \(\surd\) & \(\surd\surd\) \\ \hline Laser scanning + UWB & \(\surd\) & \(\surd\surd\) & \(\surd\) & \(\surd\surd\) & \(\surd\surd\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Capabilities of individual and integrated vision-based technologiesof the data acquired by laser scanners for 3D modeling. There are two approaches to integrating these two technologies. In one approach, the photos and scanned data are taken from the same positions, for example, the camera is installed on the laser scanner. In this approach, the extra process for coordination of different photos with scanned point cloud data is not needed, however, the photos are taken from the same distance and angle of view as scanning data which would decrease the details in photos. In another approach, photos are taken separately from scanned data but in a closer range and from different angles. Saying that in this configuration, an extra step for the orientation of the digital images with the scanned data is required [33]. This orientation can be done by choosing some common points or features in both data formats and then trying to merge them together, or by measuring the coordinates of several common points (tie points) available in both data formats in different positions [33; 50]. According to the literature, the new capabilities provided by this integration have brought new applications in construction management. For instance, through a case study in [50] the quantity of an excavation work accomplished was rapidly tracked for automated progress reporting. By using this integration, they proposed a more robust and timely data acquisition procedure in which fewer images and less scanning time is required to produce acceptable results during the 3D modeling process. They could also overcome limitations in photogrammetry technique associated with modeling objects with unclear geometrical shapes (e.g., excavation work) [25; 50]. Another application for this integration is the crack detection in an object or structure. In fact, this integration helps to improve the geometry and visual quality of the final 3D model. During the data collection phase, the information about the edges and linear features in the surface such as cracks are achieved by analysis of the images, while the information about the object geometry is provided by the scanning data. In this way, a more complete 3D model of the scene can be generated with sufficient and clear details about the color, texture, and material of various objects [33; 34].