## 1 Introduction
Next is the measurement of the spatial relationships of the longitudinal axis of the kiln and axes of rollers (measurements of position, height, additional, and special measurements) and eventually of determination of the rectifying parameters [12]. In the traditional method used to determine RK's geometric parameters, the sight/alignment line method is used for positional measurement. Precise optical theodolites are usually used. In such a case, the reference system points have the shape of one or two shifted alignment lines stabilized by markers on RK's basements. The local coordinate system is generally chosen so that one of its axes' direction is identical with the alignment line's direction and the RK's longitudinal axis. For height measurements, the method of leveling is used. The height measurement aims to determine the absolute or relative heights of the radial rollers' axes and the height of the carrier tire of RK shell. Precision analysis of geometric parameters for the RK's alignment in the cold state is described in [12]. The use of total stations (TS) and especially TLS are currently the preferred technologies of geodetic measurements of spatial objects [13; 14; 15]. Lots of experts also make achievements using TLS in several areas of research in construction and industry [8]. [PERSON] in [11] used a TLS method for the determination of the boiler geometry. [PERSON] [16; 17; 18] assessed the applicability of terrestrial laser scanning for ovality monitoring of newly built tunnels. [PERSON] applied the TLS method for tunnel measurements in [19]. Stability monitoring of architectural structure using laser scanning technique deals [PERSON] in paper [20]. TLS method has also been used in the monitoring of bridges [21; 22]. TLS was applied for the measurement of defects on concrete surfaces in [23]. For the deformation measurement of objects, the TLS method was used in works [24; 25; 26]. TLS is also a proven method of collecting spatial data; it is used as a reference for verification of reliability for other methods [27]. There are only a few current articles dealing with the rotary kiln geometry. Mostly older articles are available as [28; 29; 30]. Many online commercials confirm the importance of research of options for RK measurement, such as [31; 32; 33; 34; 35]. In doing so, companies use standard classical measurement methods. Only in [36] the TLS approach to determine the parameters of the RK is indicated. The accuracy of scan registration using the planar target is shown in [37; 38; 39]. The accuracy of the TLS method is dealt with in the works [40; 41; 42] with excellent results. We have therefore decided to apply it to the measurement of a rotary kiln. An integral part of the processing of the acquired point cloud is segmentation, which is laborious. Point cloud segmentation groups points with similar attributes with respect to geometric, colorimetric, radiometric, and/or other information. There are different methods and approaches. Segmentation of points based on geometry, intensity, or color is described, for example, in [43; 44; 45; 46]. Automated and semi-automated procedures are listed in [47; 48; 49; 50; 51; 52; 53]. Due to the specific shape of the object and the purpose of the work, we designed and tested a new procedure based on an analytical solution of the RK shell's geometry in correlation with the number of points in the histogram intervals. The aim of our research is the application of TLS measurement and verification of the analytical solution for the selection of relevant points on the RK object to determine its geometry and rectification parameters. According to the scope of this study, a workflow scheme (Figure 3) was prepared.