FAQ: Circé
Circé 5 is a geodetic transformation tool used to convert coordinates between different reference systems or projections. It supports transformations between global systems like ITRF, national system like UGRF and historical regional systems such as Arc1960. For example, if you have data in Arc1960 but need it in UGRF, Circé 5 facilitates this transformation seamlessly since it has the 7 transformation parameters and Uganda geoid model embedded in it. Circé 5 ensures consistency and accuracy when working with datasets that use different geodetic frameworks.
Circe 5 transformation software can be downloaded from the UGRF website (ugrf.mlhud.go.ug).
Circe 5 transformation software can be downloaded from the UGRF website (ugrf.mlhud.go.ug).
To transform a set of coordinates, you should use a text (TXT) file. The coordinates in the file should be organized in a tabular format, with each line containing the latitude, longitude, and height (depending on the type of coordinate). Make sure the coordinates are clearly labeled for proper transformation. This file format is compatible with transformation tools like Circé5 which will process the coordinates and output the transformed values in the desired format.
The transformation parameters used to compute transformation between the UGRF datum, and the old ARC 1960 datum have an average accuracy of 1.2m across Uganda. However, the accuracy varies in the different regions of the country as the available control points (most of the old control points were destroyed) used to process these parameters were unevenly distributed across the country.
Therefore, we are advised to start collecting geospatial data based on the ITRF05@epoch2010.0 datum so that we minimize the errors of transformation parameters.
Therefore, we are advised to start collecting geospatial data based on the ITRF05@epoch2010.0 datum so that we minimize the errors of transformation parameters.
Currently, the UGRF system supports transformations for coordinates based on Arc1960 and ITRF05 using the UTM (Universal Transverse Mercator) coordinate system, while TM (Transverse Mercator) and Cassini projections are not directly supported for transformations towards UGRF system.
UGRF is associated with UTM, which is more widely used in modern geospatial applications for accurate positioning and transformation across various regions.
UGRF is associated with UTM, which is more widely used in modern geospatial applications for accurate positioning and transformation across various regions.
Circé uses a 7 parameters transformation model (Helmert) to transform coordinates from Arc1960 to UGRN (ITRF05@epoch2010.0).
Those parameters have been processed by observing in UGRF some points previously known in Arc60.
Additionally, Circé 5 supports conversions between different types of geospatial data such as between cartesian coordinates (X, Y, Z) and geographical coordinates (latitude, longitude, and height), making it easier for surveyors to work with different types of geospatial data in their projects. By offering such transformations, UGRF ensures that users can work with the most appropriate coordinate system for their surveying tasks.
Those parameters have been processed by observing in UGRF some points previously known in Arc60.
Additionally, Circé 5 supports conversions between different types of geospatial data such as between cartesian coordinates (X, Y, Z) and geographical coordinates (latitude, longitude, and height), making it easier for surveyors to work with different types of geospatial data in their projects. By offering such transformations, UGRF ensures that users can work with the most appropriate coordinate system for their surveying tasks.
UGEOID2020A is the geoid model used currently in Uganda, and it has been computed from new gravity data measured during the 2020 DTU-Space/MLHUD airborne gravity survey of Uganda. The UGEOID2020A is based on airborne survey data, the latest satellite data from the ESA GOCE mission, terrain data and as many as available gravity field data in the surrounding countries. It is tailored to match the existing height system of Uganda through precise GPS survey of 7 primary levelling survey markers.
The UGEOID2020A has an accuracy of 3-5 cm across Uganda.
The UGEOID2020A has an accuracy of 3-5 cm across Uganda.