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Georeferencing vs. Transform Features

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11-08-2024 03:57 PM
Craig_Eissler_Iceman
Frequent Contributor

Georeferencing vs. Transforming (Edit > Transform)

Question1a: ...Is one method better than the other?

I've tried them both using vector data and am not really noticing any difference, so I'm not toally sure why there are two different tools ...unless it's just convenience depending on your workflow?

The Georeferencing 'Move to Display' button is really convenient and makes things easier to have things on one screen view.
The Edit > Transform (Transform Features) tool does NOT have a similar 'Move to Display' button, so it requires the inconvenience of Zooming back and forth. 

The Georeferencing Move/Scale/Rotate buttons are all there on the same ribbon which is convenient.
The Edit > Transform Move/Scale/Rotate tools have to be accessed independently

Georeferencing is limited to only 2 Control Points.
The Edit > Transform tool allows an unlimited number of Control Points (aka Displacement Links).

Question 1b: ...I understand that Source to Target control point accuracy using either tool is partially dependent on the accuracy of the data and the User's clicked locations -- but all things being equal, wouldn't MORE Control Points (i.e. the Edit > Transform tool) be, at least, potentially more accurate?

 

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2 Replies
RTPL_AU
Frequent Contributor

@Craig_Eissler_Iceman  I think of it as follows: Put simply Georeferencing doesn't change the source data but applies the shift & scale, etc externally to the data when viewed/used. 
Transforming the data creates a derivative dataset with new geometry that has all the shifts etc applied.

Suitability is subject to many factors. Your aversion to having multiple copies of the same data in different coordinate systems and what the impact of on-the fly georeferencing has on your computer are examples. 
I like to have a single point of truth so prefer georeferencing and keeping the source as truth. If editing of CAD data is needed I will import what I need to a FGDB in the correct CS for the task. 


 

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Craig_Eissler_Iceman
Frequent Contributor

Thanks for sharing those thoughts.

Here's a little bit more about the specifics I'm working with:

Yes, I should've mentioned I'm working with CAD data that I ultimately want in GDB format for editing/analysis, etc.

So, on the surface it would seem that Converting to a GDB then Transforming it would be the obvious workflow ...and maybe it is..?

However, like I mentioned above, working with the Displacement Links, and othe Edit tools, can be really awkward when you can't have the data 'Move to Display' like you can when Georeferencing.

...So, would it ever make sense to first Georeference, but only use the 'Move to Display' tool to make things easier once you then Convert and Transform?

...If so, that begs the other previous question I had, which is, if I'm already in the Georeferencing tool, does it make sense to go ahead and set the Control Points here?

...I ask, because I'm not certain if that limit of only 2 Control Points is considered "less accurate" than using the Unlimited Displacement Links in the Transform tool?

 

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