# Review of Photogrammetric and Lidar Applications of UAV
## 7 Conclusions  
This review has discussed and analyzed approaches for documenting, mapping, surveying, and monitoring diverse natural or artificial objects based on non-contact laser scanning and photogrammetric sensors on UAV carriers. Studies of terrain and land surface, buildings and technical objects, archeological and agricultural localities, and many other areas were included. The advantage of both methods is that they can quickly provide results with a large number of spatial data, with high accuracy and detail. The basic principles of laser scanning, photogrammetry, and the main principle of the SfM method, one of the most modern and advanced methods, were briefly explained. Nowadays, the use of non-contact methods using UAV vehicles is very popular. They are used for tracking and monitoring objects on the Earth's surface in many different applications and fields, such as research, military, agriculture, architecture, the monitoring of natural processes and phenomena, and commercial purposes. In this review, the principle of the operation of UAVs and the control of UAVs have been explained. When choosing the data collection method and the type of UAV, a surveyor must consider the size of the area to be mapped, the required point density, positional and height accuracy, the time required, and the cost. We have also addressed the advantages and disadvantages of using GCP points in surveying and using UAV with an on-board GNSS RTK/PPK module. In the next sections, we examined the use of UAV technology from a historical perspective and classified UAVs according to size, range and endurance, weight, wings, number of rotors, and purpose. The development of UAV technology also leads to its misuse, so in a separate section, we emphasized legislation and regulatory rules in selected countries. The last part of the article compared different types of UAVs in different specific conditions, with varying flight heights, types, and settings of sensors and environment. In addition, we compared the results based on GSD and RMSE.  
In this review, we adopted the terminology according to [205], and we tried to adhere to it. In the literature cited in the text, the names of UAV carriers and sensors have been kept in their original notation.  
Conceptualization L.K., B.T., P.P. and P.B.; methodology L.K., B.T., P.P., M.B. and P.B.; software, L.K., B.T. and P.F.; validation, L.K., B.T., P.P. and M.B.G.; formal analysis, L.K., B.T., P.P., P.B. and M.B.G.; investigation, L.K.; resources B.T. and P.P.; data curation, L.K., B.T., M.B. and P.P.; writing--original draft preparation, L.K., B.T. and P.P.; writing--review and editing, L.K., B.T., P.P., P.B. and M.B.G.; visualization, L.K., B.T., P.P. and M.B.G.; supervision, L.K. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Slovak Research and Development Agency under contract KEGA grant no. 055 TUKE-4/2021, KEGA 003 TUKE-4/2023 grant no. APVV-18-0351, APVV-20-0281, grant no. VEGA 1/0588/21, and project Mobile Monitoring System for the Protection of Isolated and Vulnerable Population Groups against Spread of Viral Diseases, ITMS code 313011 AUP1, co-funded by the European Regional Development Fund under the Operational Programme Integrated Infrastructure.  
Not applicable.  
The authors declare no conflict of interest.