Field Maps and data transformation

Question

Hi all

Requiring some reassurance regarding some workflow I have established for Field Maps data collection. This is building upon lots of stuff I have read on this forum and in the ESRI blogs, but require a hard-and-fast answer.

I need to know if the following process ends up with quality, high-accuracy data, or something that has been transformed into an ugly mess.

1. Field Map set up, creating feature layers based in GDA2020 Zone 56 (an Aussie system), using high accuracy GPS metadata

2. Basemap is ESRI world imagery (for export), making entire Field Map have a CRS of WGS84

3. GNSS set up to collect in GDA2020

4. Field Map location profile is performing a transform GDA2020_To_WGS_1984_2

5. Data collection occurs

I would like to know if I am losing anything in this process, particularly as it reads to me like the data is going GDA2020 > WGS 84 > (then presumably back to) GDA2020 z56. In particular, is the transform happening from the basemap CRS to the required CRS of the feature layers (GDA2020 z56)

Generally I don't have capacity to create my own basemap (therefore avoiding the WGS84) and the feature layers have to be set up in GDA2020 z56.

Anybody got thoughts on this process? Any insight appreciated.

Cheers

TanithLives · Answer

G'day @MarkWILSON_LLS . Errr, not really I am afraid. I've reverted to setting up the maps/Field Maps job in WGS 84. Establishing them in a different CRS feels like you're fighting the ESRI ecosystem - unless you want to set your own basemaps up with the required CRS. Also, it means it limits the number of transformations that occur. In our case it will be GDA2020 (RTK unit) > WGS 84 (Field Maps and Feature Layer), then I can export and transform as required. This removes one step in the transformation process, which was formerly: GDA2020 (RTK unit) > WGS 84 (Field Maps) > GDA2020 (Feature Layer).

Having said that, we are conducting a test of both these setups next week to see if we are getting any differences in survey. This should tell us if the extra transformation is actually causing any issues.

MarkWILSON_LLS · Answer

gday there @TanithLives , did you ever get any resolution on this process.

Im staring at the same problem for the first time and trying to work out what datum to create the dataset in and how to load/extract data from AGOL correctly pre and post survey.

Im using an Arrow100 with CorsNet (gda2020) feed.

thanks

mw

TanithLives · Answer

G'day @RTPL_AU . Thanks again for the reply. That all sounds promising. Yeah, the data is being collected using the full GNSS attribute metadata. I hadn't thought to actually use this to compare any transformation issues. That's a good idea. I had indeed buried myself in the available documentation about the issue - but getting a straight answer as to what might be going on was always difficult. The Location Profile is also set up correctly, running from GDA2020 > WGS84.

I think I might be unduly worrying about the data accuracy, is it sounds like the collection is happening as it should. The differentiation between what's happening with the transformation and how accurately the data is being collected is an important distinction I had not cottoned-on to. Cheers