what GNSS fields are needed to calculate accuracy?

[Kevin_MacLeod]

@ColinLawrence 

I ran the Create GPS Metadata Fields tool, to add all the GNSS fields on some layers in an editing service on SDE for use in Field Maps with Trimble R2s.

My boss asked if we can delete any of the GNSS fields, and still be able to record GPS receiver accuracy.  In other words there are a lot of fields added to the layers, and she was wondering if any are actually unnecessary. I know of course PDOP, HDOP, VDOP, and perhaps Number of satellites, Perhaps Std Dev are necessary for the Horiz and Vert accuracy fields.

But what about these fields? Can they be deleted? Are they needed to calculate horizontal and vertical accuracy? In other words if I delete these fields, will Field Maps still record data into the other fields, and populate a Horizontal Accuracy and Vertical Accuracy number in those two fields? If we are using a Trimble R2.

ESRIGNSS_DIRECTION

ESRIGNSS_SPEED 

ESRISNSR_AZIMUTH 

ESRIGNSS_AVG_H_RMS

ESRIGNSS_AVG_V_RMS 

[ColinLawrence]

Hi @Kevin_MacLeod , the GPS metadata fields are simply that, just metadata and therefore are not required in the collection of features or calculation of accuracy etc. You can remove these as you see fit however I would lean more towards hiding them instead of deleting them in case you need to come back and review previously collected data. Is there a reason your organization wants to delete them?

[BillFox]

hi Kevin,

short answer = keep them

long answer...

are you more concerned with accuracy or precision?

collecting x,y and z coordinates?

requiring US Feet or Meters?

requiring ellipsoidal or ortho-metric elevations?

some links here you probably already found and it can be a deep rabbit hole to understand it all

my eyes get blurry just thinking about it

• https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/add-xy-coordinates.htm
• https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/calculate-geometry-attribute...
• https://pro.arcgis.com/en/pro-app/latest/tool-reference/data-management/add-gps-metadata-fields.htm
•  

[DavidSolari]

There's a lot of "it depends" here but the RMS fields are the must have fields, there's virtually no reason to bother with GNSS metadata without them. ESRIGNSS_POSITIONSOURCETYPE is also a big one, this is what confirms that your users are using the equipment. The DOP data is less useful in my experience, but I'm sure someone who's spent more time with GNSS workflows can correct me here.

[Kevin_MacLeod]

Oh I wouldn't drop PDOP. I read the Trimble manual long ago and like my Canon DSLR manual, it was well-written. I know what each field means. I'm not a PLS but I've gone down the geodesy rabbit hole. I use current realizations, epochs, geoid, correction network, etc.  But end of the day I just want RMS, just horizontal; and DOP. What I'm wondering is does it need weird fields like direction or speed.  It would be nice if it could calc RMS but not require those fields to be in the layer's schema and permanently there; in other words calc it on the fly in the Field Maps app in-memory but I don't care the speed or direction or azimuth etc as permanent fields. Nor the vertical stuff.  @BillFox  Do you see what I mean?  Even if fields are used for calc, I was hoping they could be deleted and it would still calculate. I am guessing 'no' at present, but that would be a nice ENH as there are just so many metadata fields.

[BillFox]

see some early 2008 GPS rabbit holes here

Official U.S. government information about the Global Positioning System (GPS) and related topics 

( rabbit hole 1 )

(  rabbit hole 2 )

and the list of fields keeps on going as you include "Safe" field editing GPS options such as:

• Laser range finders: distance, angle, height, ...
• Underground infrastructure locating
• Drone flights / post processing
• Military
• Aviation
• Maritime
• Space
• NG911
•