{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T21:30:30Z","timestamp":1772055030713,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2023,5,22]],"date-time":"2023-05-22T00:00:00Z","timestamp":1684713600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The spatial accuracy of unmanned aerial vehicles (UAVs) and the images they capture play a crucial role in the mapping process. Researchers are exploring solutions that use image-based techniques such as structure from motion (SfM) to produce topographic maps using UAVs while accessing locations with extremely high accuracy and minimal surface measurements. Advancements in technology have enabled real-time kinematic (RTK) to increase positional accuracy to 1\u20133 times the ground sampling distance (GSD). This paper focuses on post-processing kinematic (PPK) of positional accuracy to achieve a GSD or better. To achieve this, precise satellite orbits, clock information, and UAV global navigation satellite system observation files are utilized to calculate the camera positions with the highest positional accuracy. RTK\/PPK analysis is conducted to improve the positional accuracies obtained from different flight patterns and altitudes. Data are collected at altitudes of 80 and 120 meters, resulting in GSD values of 1.87 cm\/px and 3.12 cm\/px, respectively. The evaluation of ground checkpoints using the proposed PPK methodology with one ground control point demonstrated root mean square error values of 2.3 cm (horizontal, nadiral) and 2.4 cm (vertical, nadiral) at an altitude of 80 m, and 1.4 cm (horizontal, oblique) and 3.2 cm (vertical, terrain-following) at an altitude of 120 m. These results suggest that the proposed methodology can achieve high positional accuracy for UAV image georeferencing. The main contribution of this paper is to evaluate the PPK approach to achieve high positional accuracy with unmanned aerial vehicles and assess the effect of different flight patterns and altitudes on the accuracy of the resulting topographic maps.<\/jats:p>","DOI":"10.3390\/rs15102700","type":"journal-article","created":{"date-parts":[[2023,5,23]],"date-time":"2023-05-23T01:36:48Z","timestamp":1684805808000},"page":"2700","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Improving the Spatial Accuracy of UAV Platforms Using Direct Georeferencing Methods: An Application for Steep Slopes"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8640-1443","authenticated-orcid":false,"given":"Mustafa","family":"Zeybek","sequence":"first","affiliation":[{"name":"Guneysinir Vocational School, Selcuk University, Konya 42490, T\u00fcrkiye"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4290-3684","authenticated-orcid":false,"given":"Selim","family":"Ta\u015fkaya","sequence":"additional","affiliation":[{"name":"Department of Architecture and Urban Planning, Artvin Coruh University, Artvin 08100, T\u00fcrkiye"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9766-779X","authenticated-orcid":false,"given":"Ismail","family":"Elkhrachy","sequence":"additional","affiliation":[{"name":"Civil Engineering Department, College of Engineering, Najran University, Najran 55461, Saudi Arabia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0043-5226","authenticated-orcid":false,"given":"Paolo","family":"Tarolli","sequence":"additional","affiliation":[{"name":"Department of Land, Environment, Agriculture and Forestry, University of Padova, Viale dell\u2019Universit\u00e0 16, 35020 Legnaro, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2023,5,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"834923","DOI":"10.3389\/feart.2022.834923","article-title":"Assessment of the Applicability of UAV for the Creation of Digital Surface Model of a Small Peatland","volume":"10","author":"Czapiewski","year":"2022","journal-title":"Front. 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