Using Trimble Mobile Manager with Field Maps

Question

Hello,

We have created a workflow for high-precision data collection in Field Maps using Emlid Reach GNSS. So far it works good and the measurements flow into our system smoothly. However, we can only measure coordinates using national coordinate system with corresponding vertical datum. Because Field Maps does not allow to select the geoid, we have to do postprocessing to receive the ortho height. All good, but most of the contractors are using local grid that was created long time ago using tons of measurements done with the total station. The Trimble devices can easily take that calibration file for "local site" and measure in the local site coordinates but there is no such option in Field Maps.

I am wondering is anyone tried to do the GNSS measurements in Field Maps using local grid and how was it done? I am thinking if there is a way to use Trimble Mobile Manager with GNSS receivers other than Trimble because TMM allows for local grid calibration file input.

mykola · Answer

Interesting.. so I can try somehow to transform the local site data into the geoid-like surface and use that as my geoid? Not sure if I follow... I will look for more regarding this option. We do not need very high precision from total stations, RTK is enough.

The thing about our "local" site is that this local site is actually the entire city. It was measures with total stations long time ago and the local vertical and horizontal coordinate systems were constructed. So finding the way to implement the ability to accept some kind of a calibration file in the Field Maps would be great but I doubt anything like that is coming to FM any time soon.

mykola · Answer

Yeah I have tried to use TMM before with our own geoid model and it worked fine. The thing is that we need to jump between two apps and do some adjustments here and there which is not the best solution for someone who knows little about surveying. Our goal is to provide the teams with GPS devices so they can do utility survey themselves without calling the other contractors.

It might be wise for us to ask for integration of GIS and survey. Yeah, we get improvements in drips and drops but why not integrate Trimble Access with ArcGIS Online?

Having the ability to do more in field maps with the high-precision measurements would be very helpful. Own geoid, stakeout option, localization, etc. It would significantly simplify the workflow.

JoelCusick1 · Answer

Sounds like you need a surveyor!.  Post your GRID coordinate system parameters to this surveying community, "DISCUSSION" BETWEEN NEIGHBOURS - Strictly Surveying - RPLS.com and see about asking "the keepers of the coordinate systems" to build a translation from satellite based positioning to go from Grid to Ground for you local site.  You have both horizontal and vertical components to deal with in real-time.  Take into consideration the precision of your instrument and the augmentation on site. If this site was built with a total station, its going to be part of the equation in error that you can "live with" and the obstructions overhead on site that GNSS positioning always struggles with.   You may need to resort to Total station for very high precision.  Robotic total stations and surveying software can handle jobs like this if you have extremely tight requirements.  Good luck.