Hi, I am using LocusGIS with Polaris S100 (Android app Polaris Connect with NTRIP) and when i trying to check accuracy of my equipment on some point (CUZK geodetic point) i have approx. 0,6m deviation.
After some digging, when i try to change projects reference coordinates system a layer coordinate system i found, that deviation could be made by missing transformation from ETRS89 (EPSG3045) to KROVAK (EPSG5514).
When i get coordinates of geodetic point from LOCUS GIS and manualy transform to Krovak, it seems ok (2-5cm deviation).
What settings of LOCUS GIS is responsible for tranformation coordinates from external GPS? Project reference coordinate system? Will change RefCS on existing project take effect?
Am I missing something? Is it possible to get coordinates from LOCUS in krovak?
Regards, Jan
Best Answer
P
Petr Voldan
said
over 2 years ago
Hi Jan, thank you for the message. The problem is caused due to in-accurate transformation between WGS84/ETRS89 to Krovak. The default definition of EPSG:5514 by international EPSG database uses the global Czechoslovak parameters when transformation has accuracy about 1 meter. This inaccuracy is caused by local errors in the S-JTSK network (due to historical reason when coordinate system was created). For precise transformation is required transformation with grid (apply local corrections). But mentioned Grid transformation isn't used in LocusGIS because it would brake the definition of EPSG:5514 and relation to other GIS SW.
Anyway the possible workarounds: - to set project CRS to WGS84 or ETRS89 and collect data in ETRS89 (btw: I think that the correct ESPG code for ETRS89 should be EPSG:4258) - use GeoGIS. it's more focused on Czech republic usage, the grid transformation is used and the accuracy in transformation is about 10 cm
Please feel free to describe me your use-case (even in Czech language at [email protected]) and I consider the best solution for you Thanks, Petr
1 Comment
Petr Voldan
said
over 2 years ago
Answer
Hi Jan, thank you for the message. The problem is caused due to in-accurate transformation between WGS84/ETRS89 to Krovak. The default definition of EPSG:5514 by international EPSG database uses the global Czechoslovak parameters when transformation has accuracy about 1 meter. This inaccuracy is caused by local errors in the S-JTSK network (due to historical reason when coordinate system was created). For precise transformation is required transformation with grid (apply local corrections). But mentioned Grid transformation isn't used in LocusGIS because it would brake the definition of EPSG:5514 and relation to other GIS SW.
Anyway the possible workarounds: - to set project CRS to WGS84 or ETRS89 and collect data in ETRS89 (btw: I think that the correct ESPG code for ETRS89 should be EPSG:4258) - use GeoGIS. it's more focused on Czech republic usage, the grid transformation is used and the accuracy in transformation is about 10 cm
Please feel free to describe me your use-case (even in Czech language at [email protected]) and I consider the best solution for you Thanks, Petr
Jan Krejčí
Hi,
I am using LocusGIS with Polaris S100 (Android app Polaris Connect with NTRIP) and when i trying to check accuracy of my equipment on some point (CUZK geodetic point) i have approx. 0,6m deviation.
After some digging, when i try to change projects reference coordinates system a layer coordinate system i found, that deviation could be made by missing transformation from ETRS89 (EPSG3045) to KROVAK (EPSG5514).
When i get coordinates of geodetic point from LOCUS GIS and manualy transform to Krovak, it seems ok (2-5cm deviation).
What settings of LOCUS GIS is responsible for tranformation coordinates from external GPS? Project reference coordinate system? Will change RefCS on existing project take effect?
Am I missing something? Is it possible to get coordinates from LOCUS in krovak?
Regards, Jan
Hi Jan,
thank you for the message. The problem is caused due to in-accurate transformation between WGS84/ETRS89 to Krovak. The default definition of EPSG:5514 by international EPSG database uses the global Czechoslovak parameters when transformation has accuracy about 1 meter. This inaccuracy is caused by local errors in the S-JTSK network (due to historical reason when coordinate system was created). For precise transformation is required transformation with grid (apply local corrections). But mentioned Grid transformation isn't used in LocusGIS because it would brake the definition of EPSG:5514 and relation to other GIS SW.
Anyway the possible workarounds:
- to set project CRS to WGS84 or ETRS89 and collect data in ETRS89 (btw: I think that the correct ESPG code for ETRS89 should be EPSG:4258)
- use GeoGIS. it's more focused on Czech republic usage, the grid transformation is used and the accuracy in transformation is about 10 cm
Please feel free to describe me your use-case (even in Czech language at [email protected]) and I consider the best solution for you
Thanks, Petr
Petr Voldan
Hi Jan,
thank you for the message. The problem is caused due to in-accurate transformation between WGS84/ETRS89 to Krovak. The default definition of EPSG:5514 by international EPSG database uses the global Czechoslovak parameters when transformation has accuracy about 1 meter. This inaccuracy is caused by local errors in the S-JTSK network (due to historical reason when coordinate system was created). For precise transformation is required transformation with grid (apply local corrections). But mentioned Grid transformation isn't used in LocusGIS because it would brake the definition of EPSG:5514 and relation to other GIS SW.
Anyway the possible workarounds:
- to set project CRS to WGS84 or ETRS89 and collect data in ETRS89 (btw: I think that the correct ESPG code for ETRS89 should be EPSG:4258)
- use GeoGIS. it's more focused on Czech republic usage, the grid transformation is used and the accuracy in transformation is about 10 cm
Please feel free to describe me your use-case (even in Czech language at [email protected]) and I consider the best solution for you
Thanks, Petr
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