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1. What is KSA-GRF17?
Kingdom of Saudi Arabia Geodetic Reference Frame 2017 (KSA-GRF17) is the latest realization of the National Geodetic Reference System (KSA-GRF) developed in 2019 at General Autharity for Survey and Geospatial Information  (GASGI), KSA.
The KSA-GRF17 is based on the ITRF2014 reference frame, and the epoch of 2017.0 is the epoch when both reference frames coincide. At that epoch, the coordinates are the same in both reference frames, but they diverge with respect to each other at any epoch different from 2017.0 due to the Arabian plate rotation.

2. How KSA-GRF17 is realized?
The KSA-GRF17 is realized by the values of Cartesian coordinates of 332 stations in KSACORS, MOMRA, ARAMCO and KACST CORS (Continuously Operating Reference Station) Networks in KSA. These values have been computed at the GASGI during processing of GPS observations from the listed Networks.

3. What Reference Frame (RF) type is the KSA-GRF17?
The KSA-GRF17 is plate-fixed RF, which attempts to “affix” the coordinate frame (longitude and latitude only) to the Arabian tectonic plate so that to maintain unchanged coordinates w.r.t the plate.

4. What ellipsoid shall I use to relate Cartesian coordinates in KSA-GRF17 to geodetic coordinates (latitude, longitude, ellipsoidal height)?
GRS 1980 ellipsoid.

5. Who is responsible of maintaining the KSA-GRF17?
General Authority for Survey and Geospatial Information (GASGI, former GCS).

6. What other RFs are the most used in KSA?
Ain Al Abd 1970 (AAA), ARAMCO-AAA, ARAMCO-WGS84 (ITRF1994 at epoch 1998.0), MTRF2000 (ITRF2000 at epoch 2004.0), GDMS (ITRF2000 at epoch 2003.1998).
7. How different are the coordinates in KSA-GRF17 in comparison with coordinates in other RFs used in KSA?

​Reference System
​Horizontal shift  [m]​
ARAMCO-AAA​93
ARAMCO-WGS84​0.80​
GDMS​0.60
MTRF-2000​0.60
8. What are the benefits of using KSA-GRF17?
The KSA-GRF17 is the most accurate RF available in KSA. All important geospatial activities in the Kingdom require one unified National Geodetic Reference System.
Moreover, it allows: 
  • To simplify processes: GNSS measurements (processed in appropriate way) will give a position in KSA-GRF17 directly (post-processing or RTK, static or kinematic, local or countrywide).
  • To improve data quality – no transformation will be needed between different RFs, therefore, no accuracy degradation will occur.
  • To avoid mistakes which might happen because of use of different RFs for different tasks and by different institutions.
  • To save money and time because it will be no need in coordinate transformation and making additional observations required to compute transformation parameters.
9. How can I get access to KSA-GRF17?
10. How can I transform coordinates from the Reference Frame I am using to KSA-GRF17?
Use Online Coordinate Transformation Tool to transform coordinates from the Reference Frame you are using to KSA-GRF17.

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