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Unstable Projection? Data not lining up, why?

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03-26-2019 05:15 AM
JacquelineAlessi
Occasional Contributor II

I have several FDS that are set to Nad State Plane South (WKID: 2253) that I want to project to WGS 84 WEb Mercator (WKID: 3857). I have been using the NAD_1983_to_WGS_1984_5 transformation. This was working for a while but now my WGS datasets are drawing about 3 feet off of where the points were. I didn't change any of the parameters in my GP tool. I can run the Projection in catalog, pull the FC into an MXD with Imagery and they are fine, but once I save the map and reopen it the imagery and FC no longer align. The imagery and the FC are the same Coordinate system. Please help! 

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11 Replies
MatthewDriscoll
MVP Alum

Sounds like it might be a meter-feet issue.  Check to make sure they are using the same type of units.

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JacquelineAlessi
Occasional Contributor II

Of Course they dont, State plane is feet and WGS is in meters. But that still doesnt adress the issue. this projection process has worked Since December without issue. NOW, as of yesterday it doesnt work. 

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MatthewDriscoll
MVP Alum

Sorry I meant does the map have the same units as the imagery and FC?  I agree this should not matter, trying to narrow it down.    

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JacquelineAlessi
Occasional Contributor II

Yes once projected to WGS 84 they are set to the same units. 

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MatthewDriscoll
MVP Alum

Does the same thing happen if you use WGS_1984_(ITRF00)_To_NAD_1983?

According to this article NAD_1983_To_WGS_1984_5 has an accuracy of 2 meters where WGS_1984_(ITRF00)_To_NAD_1983 is 0.10.

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JacquelineAlessi
Occasional Contributor II

Yeah it is identical either way. 

That was my first ditch effort, also as a side note it was the Transformtion that I argued for in the first place but in my work place the the microsoft developers know more, and we dont get much of a say... 

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MatthewDriscoll
MVP Alum

Sorry, I am out of ideas.  Hopefully someone else with better knowledge on this behavior chimes in.  Not sure if there is a size limit for uploading here, but if you are able to attached the imagery and feature class to the thread please do so.  

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JacquelineAlessi
Occasional Contributor II

Haha No I cant its all confidential. 

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MelitaKennedy
Esri Notable Contributor

Hi Jacqueline,

Is the same transformation set in the map? Are you using ArcGIS Desktop or Pro? Which version?

As I think you know, 3 feet / 1 meter is a classic sign that a transformation isn't being applied  for data that's in NAD83 versus WGS84 so it is certainly something to do with a transformation.

Melita

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