Mapping and GIS Solutions Community

Hello,

I learned that Exports from TerraFlex assigns shapefiles with a WGS84 PRJ (Datum Tag).  If this is the case, and a user is receiving augmentation NOT in WGS84 (say NAD83 (2011) epoch 2010., what is TerraFlex doing upon export.

Is it.

A) Calling any export regardless of augmentation "WGS84".  Similar to a shapefile export from TerraSync at the device

or

B) Shifting the Datum internally to WGS84 FROM ether Map or augmentation system to WGS84.  If B., what is the shifter?

I suspect that the answer is A.  If that is the case, its impossible to be "IN" WGS84, and what I am hearing alot of these days is VRS, NTRIP, RTX and other augmentations that many are feeding off of.  This could be a real kick in the pants for someone consuming said shapefile in ArcMap. ArcMap listens to PRJ's (like the ring that Gollum wants) and its very, very powerful.

Joel

Hi Joel

All this is addressed and resolved in the Positioning section of your Map Workspace document (where you configure the real time option for Terraflex mobile)

In the Map workspace > select the hamburger menu option > Positioning menu

Here you can add a real-time option to be used by the field worker in Terraflex mobile

Terraflex will apply the correction datums used by the RTX and SBAS services so there's nothing to configure here other than to choose RTX or SBAS service from the drop down.

If you are using VRSNow (or any other NTRIP provider) you will need to define the correction datum this service is using for this to be applied correctly.

This is done using the DATUM options we provide when you are setting up the NTRIP

Providing this is done correctly there will be no positional errors associated with datums.

Thanks Tom for the reply.

Good steps to follow.   See if I get this right (and from a different angle).  If you could answer this at a deeper level, the user community could use this information.  The GIS community is, for most of us, use to transformations, and, we understand that transforms, when applied correctly today, are 7 parameters, and when worked in forward or reverse directions, the math zero's out.  But we would like to hear from the team what exactly is going on.

Assume for this example, i'm using NTRIP with NAD83 (2011) streaming incoming data, and my final output, I want in NAD83 (2011) for consumption in, say an ESRI world.  Take us thru this will you?

From the Field to the Map.....

Assume I set properly the datum for NTRIP to NAD83(2011).   TerraFlex, on the fly transforms the incoming positions to the Map Space in Terraflex,? or does it move the basemap to the assigned incoming datum.? The former shifts the data TO WGS84, the latter shifts the data FROM WGS84

Next, in Map Workspace, I am assuming the basemap remains always in WGS84.  Is that correct?

If so, then from the field is workspace shifting the stored positions that are synced to WGS84 for display?

I am loosely referring to WGS84, which is not the correct datum (ITRF, IGS08), but for simplicity, this bear with that term.

thanks for your time.

Hi Joel

Terraflex only operates in WGS84 at the moment

• This means on import your dataset will be transformed to WGS84
  • For shapefile/gdb this means the workspace reads the WKT out of PRJ and matches this with our own lookup list
• In the Map Workspace your imported data will be in WGS84
• Any collected field data in Terraflex will be in WGS84
  • As above - If your real-time source is based on another correction datum, then this needs defining as the example above, Terraflex will then 'zero' the transformation, as you put it, and shift the data to WGS84 to compensate for the shift.
  • The WMS used by Terraflex is in WGS84 so there is no need to define this like you do in ESRI
• On Export your data will be in WGS84

The only exception to this is If you are using the free Terraflex Add-In for ESRI ArcMAP which is recommended for ESRI users 

In this case, as the Add-In operates inside ArcMAP, so you have the ability to work in your local Coordinate system and define the transformation as part of the Terraflex Project setup

• The Terraflex Add In - User guide includes more detail on this.

The latest version of the TerraFlex add-in for ArcMap v4.02 which you can download and start using for free providing you have a valid Terraflex subscription

Tom,

Okay, thanks for the reply.

We will be using the TerraFlex Add in, and I get that scenario quite well.

One more question, please confirm on the Export from Terraflex (from the workspace "map" when returning to the office.

Q. Is the data defined with a PRJ file *.prj ?  If so, is that PRJ 4326 (WGS84).   WGS 84: EPSG Projection -- Spatial Reference 

thanks for your time in this matter of Shifts.

Joel

No problem Joel

Yes you are correct - it's EPSG 4326
The *prj file for shapefile exports are defined as GCS_WGS_1984 (WKID: 4326 Authority: EPSG)