Coordinates transfo
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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.
Transformation parameters have been calculated in 2019 between Arc60 and UGRF, using the best repartition of points known in both systems (18 points).
The following transformation parameters have therefore been adopted from the UGRF reference frame to Datum Arc 1960:
| From | To | Tx (m) | Ty (m) | Tz (m) | D (mm/km) | ∈x (") | ∈y (") | ∈z (") |
|---|---|---|---|---|---|---|---|---|
| UGRF | Datum Arc 1960 | +136.7231 | +87.8654 | -20.1215 | -7.86009 | -4.966933 | +9.010010 | +2.724860 |
The accuracy of this transformation is about 50 cm to 1 meter (according to the RMS of the residuals). Adding more points would enable the improvement of transformation parameters. For example, the measurement of around 100 points known in both systems could lead to the calculation of a full transformation grid.
IAG GRS 80 is the ellipsoid associated with the UGRF geodetic reference system. The IAG GRS 80 ellipsoid is defined by the following constants (exact value for a, derived value for f):
| semi-major axis: | a = 6,378,137.0 m |
| flattening: | f = 1/298.257 222 101 |
The geodetic reference frames in Uganda are associated with the UTM projection. Uganda is covered by 4 different zones: UTM North zone 36, UTM North zone 35, UTM South zone 36, and UTM South zone 35. Please be aware of the UTM zone you are working with when using UTM-projected coordinates.
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 systems 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 the Uganda geoid model embedded in it. Circé 5 ensures consistency and accuracy when working with datasets that use different geodetic frameworks.