We've been asked to retrace a survey of a buried pipeline, and use that survey to mark on the ground the position of the pipeline. The survey was done with a Trimble R2 GNSS receiver and Trimble RTX correction services. The pipe position was found with a pipe locator. The survey report says the R2/RTX combo gave submeter accuracy. After a little www research I can see that there are various "grades" of RTX correction, ranging from 4cm to submeter. So maybe the survey used one of the lower grades.
We intend to use RTK-GNSS base and rover with SurvCE V5 to try and mark the surveyed pipe points on the ground. The survey report gives horizontal position as decimal Lat and Lon to 12 decimal places and elevation in meters to 5 decimal places. We intend to localise the RTK on a pipe point that is at the surface, or exposed, like a valve. According to Trimble's own FAQ, the RTX uses a ITRF2014, so presumably the report coordinates are ITRF2014 transformed to WGS84 so we can just use WGS84 system in SurvCE for our RTK?
I see also that the coverage map is not quite world wide and we are on an island north of New Zealand, so I can't see if the blue area covers us, and perhaps the original survey wasn't getting corrections and perhaps it was just autonomous.
Presumably there's a logical reason why oceans are not covered.
If you need to accurately mark the position of the pipeline on the ground I'd suggest investing in a pipeline locator such as the Radio Detection RD-8100 and a few probes.
Anytime I use RTX (I have one R10 with a subscription) I transform the results to what the client requests, usually NAD83 (2011), but occasionally ITRF at a different epoch date. Of course you are not using NAD83 down there, my point is that the results can be easily transformed to other datums/epochs, so metadata is needed to know what was done with the coordinates.?ÿ
