## 2 Materials and Methods
### Surveying Equipment and Data Acquisition  
The in-situ TLS survey was realized during the kiln shutdown and its overhaul--the so-called \"cold state\". The measurement was carried out in the local coordinate system used across the whole factory. The positive direction of the axis Y is parallel to the nominal axis of the RK. The survey was connected to the points of the local survey net of the plant in the vicinity of the RK. The location of all survey points distinguished by color is shown in Figure 5. Given its size, this net is established as planar, i.e., the net scale factor is 1. The connection points are marked by nails in the concrete foundations of buildings and technological objects. Leica TCRA 1201+ total station (TS) and the method of the temporary station for the connection measurement were used (Figure 6a). The horizontal (X and Y directions) and vertical (Z-direction) RMSD of these points and coordinates of free station derived from the reference network points is less than \(\pm\)1 mm. Figure 4: The rotary kiln—the object of research. Figure 5: An overview of the location of all survey points distinguished by color: 1—connecting points of the survey net; 2—ground control points (GCP); 3—scanning stations; 4—total stations (TS) survey station. Ground Control Points (GCP) for the TLS were marked temporarily. Leica circular HDS targets on geodetic tripods and mini-tripods and magnetic targets (Figure 6b) were used to connect the TLS survey to a common coordinate system. The spatial polar method with reflectorless distance measurement from a single set-up was used to determine the center of the targets' coordinates. The measurement was done in two faces of instruments' telescope. Total station's selected technical specifications include an angular accuracy (horizontal and vertical) of 0.3 mgon, and the distance measurement accuracy, which is according to ISO 17123-4 1 mm + 1.5 ppm in the standard measurement mode. A red laser with a 633 nm wavelength may be used in the phase measurement configuration when accuracy reaches 2 mm + 2 ppm [54]. For measurement of the orientations, Leica GMP 111 mini prism was used. Automatic Target Recognition (ATR) was applied. The ATR accuracy 0.3 mgon (standard deviation), according to ISO 17123-3. The horizontal accuracy of GCP determination is expressed by the standard deviation \(\mathrm{m_{p}}\) of the measured point according to Equation (2):  
\[m_{P}^{2}=m_{pA}^{2}+\sin^{2}z.m_{S}^{2}+s^{2}.\cos^{2}z\left(\frac{m_{z}}{ \rho}\right)^{2}+s^{2}.\sin^{2}z\left(\frac{m_{\omega}}{\rho}\right)^{2} \tag{2}\]  
where:  
\(m_{pA}\)--standard positional deviation of the connection points,  
\(s\)--slope distance,  
\(z\)--zenith angle,  
\(m_{\omega}\)--standard deviation of the horizontal angle,  
\(m_{z}\)--standard deviation of the zenith angle,  
\(m_{s}\)--standard deviation of the distance,  
\(\rho\)--coefficient of angular conversion  
The vertical accuracy of GCP is determined by the standard deviation \(m_{h}\) derived for trigonometric height measurement by Equation (3):  
\[m_{h}^{2}=m_{hA}^{2}+\cos^{2}z.m_{S}^{2}+s^{2}.\sin^{2}z\left(\frac{m_{z}}{ \rho}\right)^{2} \tag{3}\]  
where:  
\(m_{hA}\)--standard height deviation of the connection points. For the GCP internal accuracy for the furthest measured points from the standpoint, where \(s\) = 80 m, \(z\) = 105 g; the values of standard deviations were calculated \(m_{P}\)\(\leq\) 2 mm and \(m_{h}\) = \(\leq\) 2 mm. For the TLS survey, Leica ScanStation C10 laser scanner instrument (Figure 6c) was used. The technical parameters of the scanner are described in [55]. The TLS survey was performed from five survey stations with a direct connection to GCPs by the resection method. The mutual registration of scans was performed directly in the field. The total accuracy of scan registration was up to 2 mm. This  
Figure 6: Surveying equipment (**a**) Leica TCRA 1201+, (**b**) 6.5 inch HDS target, (**c**) Leica Scanstation C10. corresponds to the value of RMSD in determining a temporary station.