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Geographic Transformation Warning

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10-13-2023 05:27 PM
Craig_Eissler_Iceman
Occasional Contributor III

See attached.

It is not totally clear to me how these two settings relate: Options > Map and Scene: Transformation Warning AND Map Properties > Transformations

Even with the Transformation Warning option checked, I do not receive a warning when I add a layer requiring it; the layer's datum is different than the map's datum.

However, ArcGIS does automatically perform the transformation (because I can see that it aligns properly) AND I will now see it in the Map Properties > Transformations list.

Can someone explain?
Thanks

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DanPatterson
MVP Esteemed Contributor

1 yes

2 convenience option or preparation for data one is going to get


... sort of retired...

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DanPatterson
MVP Esteemed Contributor

Even with a brand new map?

Did you by chance store a transformation?

Specify a datum transformation—ArcGIS Pro | Documentation (see Store additional transformations in a map )

The warning, I suspect, should happen the first time at least if the map and file datums are different.

Did you test with an empty map ( no basemap), define its coordinate system, then add a single featureclass with a different datum to it?  If so, report the result.  If no success, ... Tech Support. I don't see any bug on the tech support site.


... sort of retired...
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Craig_Eissler_Iceman
Occasional Contributor III

Thanks, Dan. OK, upon trying things again, I see the Transformation Warning. Evidently, my previous observation was when I was adding a second layer with the same datum as a layer that had already been added. Apparently the Warning only occurs the first time there is a difference in datum between the first layer and the map. 

So, when that first layer is added (with a different datum than the map), ArcGIS automatically applies the most suitable transformation to complete the projection on-the-fly process. Then, that specific transformation gets added to the Transformation list and the Warning is no longer provided for that same datum difference situation.

Q1: ...Am I correct about above?

Q2: Regardless, what's the purpose of manually adding a transformation to the Transformation list?

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DanPatterson
MVP Esteemed Contributor

1 yes

2 convenience option or preparation for data one is going to get


... sort of retired...
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