I'm a student studying surveying and analysis. I have gathered coordinates data on the same point via VRS, RTK, and Thingstream's PPP.

It seems like VRS and RTK goes similar, but PPP keeps getting coordinates that are transitioned by similar distances.(~0.8m)

I have heard that when RTK surveying, one must know the coordinates of the stations. And I know for a fact that RTK(We use our school's stations) and VRS were using coordinates from 2000, and PPP is using coordinates from 3 months ago.

What could be the leading factor of this error?

During this period, My country's Datum(South Korea, ITRF2000 -> KGD2002) has changed. Alongside the drifting of the continents(~1.7cm/year). Can this change in the datum be the leading cause?

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1 Answer 1


Tectonic plate movement definitely has to be taken into account. But if you multiply your 1.7 cm/year plate movement by 23.5 years that only gives 40cm of drift and you say you're seeing a shift of about 0.8M.

When you say "RTK(We use our school's stations) and VRS were using coordinates from 2000", do you know what datum these coordinates were in? If these were in the older KTN1987, there's a good possibility that the change from KTN1987 to KGD2002 explains some of the shift.

The article here gives a history of South Korean Geodetic reference systems, KTN1910, KTN1957, KTN1987, and KGD2002, but I can't find anything which gives the difference in positions between KTN1987 and KGD2002.

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