conversion form WGS84 Web Mercator (auxiliary sphere) to NAD 1983 (2011) StatePlane New York East FIPS 3101 (US Feet)

[Suedietrich]

Hi everyone,

We have been collecting data with a GPS unit in NAD 1983 (2011) StatePlane New York East FIPS 3101 (US Feet). Then the Collector for ArcGIS App were converting this to WGS84 Web Mercator (auxiliary sphere) as it was using ESRI basemaps. Now I am trying to project the GPSd data to NAD 1983 (2011) StatePlane New York East FIPS 3101 (US Feet). What would be the best practice to revert back to its original state. Thanks,

[RPGIS]

You can either define its projection using the Define Projection tool or the Projection Tool.

[Suedietrich]

Hi @RPGIS ,

thank you for your reply. When I use projection, the data doesn’t align perfectly with the orthoimagey which uses NAD 1983 (2011) StatePlane New York East FIPS 3101 (US Feet).

[RPGIS]

Your welcome @Suedietrich 

Then it sounds like you may have to use the define projection tool in conjunction with the project tool, or you could try to copy the data over using that projection. This is a pretty common issue with when it comes to converting projections.

Or another option is to convert it to WGS 1984 Web Mercator and then re-project the data to the projection that you want.

Try these options to see if either of these works. If not, then either I or someone in the community can give you some other options to try.

[DanPatterson]

A caution...

Define Projection should only be used for a data source that does not have a defined coordinate system.

If your data has a defined coordinate system (as confirmed within the properties with Pro or ArcMap), then you can project it to whatever you want.

However, "projection-on-the-fly" is supported by both software packages and it will automagically be projected to the coordinate system that is used by the map (data frame).

If you have a preference for working in a particular coordinate system, then "Project" the original data to produce a new dataset in the desired coordinate system.  You will then have the original and desired variants of the data.

Again... don't "Define" anything that is already defined... bad things happen if you do

[JoelCusick1]

Hi Dan (who is sort of retired),

I zeroed in on your comment that "don't define anything that is already defined.... bad things happen".

We use Define projection, even when the dataset is defined, to alter what we know is the projection/datum of the data.  We have not experienced issues.  

We get this is not projecting, but its a powerful method when consuming data, say from a Trimble workflow that inappropriately assigned a non-ESRI or EPSG projection but we "know" what it should be.   I think your referring to bad things if you start using Define over Projection to "move" data which Define does not do.  Just clarifying thats all.

thanks Dan for the help over the years.   Can't wait till 2025 eh?   This new datum is going to be a shaker.

[BojanŠavrič · Accepted solution]

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@Suedietrich wrote:

When I use projection, the data doesn’t align perfectly with the orthoimagey which uses NAD 1983 (2011) StatePlane New York East FIPS 3101 (US Feet).

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If your data does not align perfectly, sounds to me that there was/is missing (or different) transformation path in your workflows.

Add your GPS data and the orthoimagey to your map in ArcGIS Pro and set Map's coordinate system to NAD 1983 (2011) StatePlane New York East FIPS 3101 (US Feet). Go to Transformation tab and try the first three possible transformation paths (<None>, WGS 1984 (ITRF08) To NAD 1983 2011, WGS 1984 (ITRF00) To NAD 1983 2011) and see if any of them aligns your data perfectly. The one that does is probably the path that was used by the Collector when converting your data to WGS84 Web Mercator (auxiliary sphere). My guess would be that the Collector probably used WGS 1984 (ITRF00) To NAD 1983 2011 or <None>.

Then use Project tool, as @DanPatterson suggested, to convert your GPS data back to NAD 1983 (2011) StatePlane New York East FIPS 3101 (US Feet) and use the same transformation path that the Collector used.

I hope this helps,
Bojan

[Suedietrich]

Thank you so much @BojanŠavrič , @DanPatterson  and @RPGIS .  Everything aligned perfectly now. The Collector app applied WGS 1984 (ITRF08) To NAD 1983 2011 transformation.

Have a great day.