Trying to understand Georeferencing behavior - vanishing control points

Question

Hello all,

Wondering if anyone can help me understand how control points should behave when Georeferencing in Pro 3.4.3 - it seems to unpredictable (i.e. buggy) for me, but maybe there is a consistent logic to it that I am not aware of.

In short, it seems like sometimes the control points for a georeferenced image disappear at random, while other times they persist indefinitely across multiple sessions. Generally, I am able to georeference and save a raster, close georeferencing, then e.g. georef another image, close Pro, etc., and when I open georeferencing for that raster in a subsequent session the points are all still present - so I can modify them if needed. However, other times, when I reopen a previously referenced raster, the image stays correctly stretched, rotated, and referenced, but the control points are gone.

Which of these behaviors is the default that I should expect consistently? Is there something I should be doing to ensure that points always persist?

Thanks in advance for any clarification folks can provide!

VenkataKondepati · Answer

You have hit the nail on the head. You can generally infer that if the raster and its sidecar files stay put, those points should be there when you re-open the session—but in the world of Pro, "should" isn't a guarantee.

The reality is that Pro treats the Control Point Table as session metadata; while it tries to re-link that table to the raster's .aux.xml file, any slight hiccup in the file path or a crash can break that bond. Saving your points to a .txt file is the only way to move from "hoping it works" to a bulletproof workflow.

JasperRomero · Answer

@VenkataKondepati thanks for the response - is it correct to infer that in general, if files aren't moved, the control point table will usually (but won't necessarily always) persist between sessions?

In any case, sounds like I'll be saving all my control points from here on out.

VenkataKondepati · Answer

The short answer is that the "disappearing" act happens because of how Pro handles Auxiliary Files vs. the Control Point Table.

Here is the reality check on the logic:

The "Locked-In" State: When you hit Save, Pro writes the transformation into an .aux.xml file. At that point, the raster is "referenced," but the actual Control Point objects are often flushed from the active session memory to keep the project light.

The Persistence Trick: If you want those points to survive every single time, you must Export Control Points to a .txt file. Think of the .aux.xml as the final "baked" result and the .txt file as your "source code."

Why they vanish: If you move the raster to a new folder or rename it, Pro loses the link to the hidden metadata file. The image stays "stretched" because the header was updated, but the points are gone because the sidecar file didn't follow it.

Don't rely on Pro to "remember" the session. Always manually Save Control Points before closing the Georeferencing tab. This ensures you can always Load them back in if the UI decides to wipe the slate clean.