Slope deformations, i.e., all types of landslides of rock masses (flow, creep, fall down, etc.), caused by gravitational forces, are the most widespread implementation of geological hazards and a negative geomorphological phenomenon that threatens the security of the population, destroy all utility values of the affected regions, negatively affects the environment, and cause considerable economic damage. Nowadays, the Global Navigation Satellite Systems (GNSS) provide accurate data for precise observations around the world due to the growing number of satellites from multiple operators, as well as more powerful and advanced technologies and the implementation of mathematical and physical models more accurately describing systematic errors that degrade GNSS observations such as ionospheric, tropospheric, and relativistic effects or multipath. The correct combination of measurement methods provides even more precise, i.e., better measurement results or estimates of unknown parameters. The combination of measurement procedures and their significant evaluations represent the essential attribute of deformation monitoring of landslides concerning the protection of the environment and the population’s safety in the interest areas for the sustainable development of human society. This article presents the establishment and use of a local geodetic network in particular local space for various needs. Depending upon the specific conditions, it is possible to use GNSS technology to obtain accurate observations and achieve the results applicable to the deformation survey for subsequent processing of the adjustment procedure.

The article presents the results of research on the development of a method for improving the positioning accuracy of an UAV equipped with a single-frequency GPS receiver for determining the linear elements of exterior orientation in aerial photogrammetry. Thus, the paper presents a computational strategy for improving UAV position determination using the SPP code method and the products of the IGS service. The developed algorithmswere tested in two independent research experiments performed with theUAVplatform on which an AsteRx-m2 UAS single-frequency receiver was installed. As a result of the experiments, it was shown that the use of IGS products in the SPP code method made it possible to improve the accuracy of the linear elements to the level of about ±2.088 m for X coordinate, ±1.547 m for Y coordinate, ±3.712 m for Z coordinate. The paper also shows the trend of changes in the obtained accuracy in determining linear elements of exterior orientation in the form of a linear regression function. Finally, the paper also applies the SBAS corrections model for the improvement of UAV position calculation and determination of linear elements of exterior orientation. In this case, the improvement in the accuracy of determining the linear elements of exterior orientation is about ±1.843 m for X coordinate, ±1.658 m for Y coordinate, ±7.930 m for Z coordinate. As the obtained test results show, the use of IGS products and SBAS corrections in the SPP code method makes it possible to improve the determination ofUAVpositions for the use in aerial photogrammetry. Keywords: UAV, GNSS measurements, linear elements of exterior orientation, accuracy.

The article discusses the applicability of a novel method to determine horizontal curvature of the railway track axis based on results of mobile satellite measurements. The method is based on inclination angle changes of a moving chord in the Cartesian coordinate system. In the presented case, the variant referred to as the method of two virtual chords is applied. It consists in maneuvering with only one GNSS (Global Navigation Satellite System) receiver. The assumptions of the novel method are formulated, and an assessment of its application in the performed campaign of mobile satellite measurements is presented. The shape of the measured railway axis is shown in the national spatial reference system PL-2000, and the speed of the measuring trolley during measurement is calculated based on the recorded coordinates. It has been observed that over the test section, the curvature ordinates differ from the expected waveform, which can be caused by disturbances of the measuring trolley trajectory. However, this problem can easily be overcome by filtering the measured track axis ordinates to obtain the correct shape – this refers to all track segments: straight sections, circular arcs and transition curves. The virtual chord method can also constitute the basis for assessing the quality of the recorded satellite signal. The performed analysis has shown high accuracy of the measuring process.