FAQ: CORS - Datum and Coordinate
The UGRF network is the realization of the UGRF reference system, the official Uganda Reference system. It is aligned to ITRF2005@epoch2010.0 as its geodetic datum. This global, earth-centered datum ensures high accuracy and consistency for geospatial applications, aligning Uganda's geodetic infrastructure with international standards.
The Uganda Geodetic Reference Framework (UGRF) is based on the ITRF2005@epoch2010.0 datum, which ensures that Uganda's geodetic data aligns with global standards for positioning and navigation. By adopting this globally recognized reference frame, UGRF provides a reliable foundation for integrating geospatial data with international systems. This compatibility facilitates accurate measurements using GNSS technologies, seamless data sharing across borders, and alignment with regional and global geodetic initiatives. Additionally, the UGRF's alignment with ITRF supports various applications, including surveying, mapping, infrastructure development, and scientific research, while enhancing the accuracy of geospatial products in Uganda and beyond.
UTM (Universal Transverse Mercator) is a map projection that transforms the curved surface of the Earth into a flat surface. It divides the Earth into 60 zones while minimizing distortions for accurate mapping. Uganda lies in zone 35 and Zone 36.
UTM coordinates can be computed in both UGRF (aligned with ITRF) and ARC60, but the results differ due to the underlying datums. Transformation model (Circe 5) is available to transform coordinates from one datum to another.
UTM coordinates can be computed in both UGRF (aligned with ITRF) and ARC60, but the results differ due to the underlying datums. Transformation model (Circe 5) is available to transform coordinates from one datum to another.
UGRF was designed and processed from 9 'zero-order' points that were measured in 2010, while the latest and most accurate ITRF was ITRF05.
Switching to ITRF2020 would create an offset of about 30cm without increasing serious accuracy and would probably create a source of disorder among users.
Switching to ITRF2020 would create an offset of about 30cm without increasing serious accuracy and would probably create a source of disorder among users.
Arc 1960 is a regional geodetic datum established in the 1960s for East Africa, based on older terrestrial survey methods and on the Clarke 1880 ellipsoid. It is less precise and primarily suited for traditional mapping and surveying. Its precision is about 1cm/km.
In contrast, the International Terrestrial Reference Frame (ITRF) is a dynamic, global geodetic reference system regularly updated using advanced techniques like GNSS, VLBI, and SLR. ITRF offers sub-centimeter precision, accounts for tectonic movements, and uses modern ellipsoids like GRS80 or WGS84, making it ideal for global positioning, navigation, and scientific applications.
Its accuracy is better than 0.1mm/km and can reach 1cm /1000 km.
Transitioning to ITRF ensures more accurate and consistent geospatial data for modern needs.
In contrast, the International Terrestrial Reference Frame (ITRF) is a dynamic, global geodetic reference system regularly updated using advanced techniques like GNSS, VLBI, and SLR. ITRF offers sub-centimeter precision, accounts for tectonic movements, and uses modern ellipsoids like GRS80 or WGS84, making it ideal for global positioning, navigation, and scientific applications.
Its accuracy is better than 0.1mm/km and can reach 1cm /1000 km.
Transitioning to ITRF ensures more accurate and consistent geospatial data for modern needs.
Due to the high differences in precision between the two systems, there is no doubt that using UGRF is the only solution to keep the accuracy obtained with GNSS measurements and to be consistent with orthophotos and all GIS data.
Anyhow, old data cannot be deleted, and a way has to be found to get the most possible intimations from this old data. The only way to use it is to transform ARC60 into UGRF, remembering that the inconsistencies that may happen are coming only from the inaccuracy of the ARC60 data. The only way to improve the transformation parameters from ARC60 to UGRF would be to increase the number of points known in both systems.
Transforming UGRF data into Arc60 means degrading the quality of the data initially obtained in UGRF.
It is highly recommended to use only UGRF data and leave apart all Arc60 coordinates.
Anyhow, old data cannot be deleted, and a way has to be found to get the most possible intimations from this old data. The only way to use it is to transform ARC60 into UGRF, remembering that the inconsistencies that may happen are coming only from the inaccuracy of the ARC60 data. The only way to improve the transformation parameters from ARC60 to UGRF would be to increase the number of points known in both systems.
Transforming UGRF data into Arc60 means degrading the quality of the data initially obtained in UGRF.
It is highly recommended to use only UGRF data and leave apart all Arc60 coordinates.