Error in SNAP GCP Tool

snap
#1

Dear SNAP-Team,

I want to report an issue with the GCP-Tool in SNAP.

In my Remote Sensing class I am teaching Reprojection using the GCP tool together with the Reprojection wizard.

The problem is as follows:

  1. My students have to reproject a satellite scene (Landsat 7) without Geo-Coding to a Landsat 7 scene with Geo-Coding

  2. My students have to place GCPs in the scene with the geocoding and at exact the same location in the scene without the geocoding

  3. Now they copy the Lon and Lat Information from one GCP-Manager to the other (Is there a better way how to assign the Lat and Lon to the scene without the Geo-Coding? For example automized via the Label? It is such a pain to copy the Lat and Lon by hand)

  4. Now the Problem: When Attaching / Detaching GCP Geo-Coding, the X and Y values change when clicking on the table -WHY?

Here the GCP after attaching GCP Geo-Coding without a click on the table:

GCP_without
GCP_without1083×370 45 KB

And Here after clicking on the GCP 1 and GCP 3 in the table afterwards. X and Y coordinates change to something totally different and don’t make any sense. This is confusing my students a lot!

GCP_with
GCP_with1197×361 46.3 KB

I hope this problem can be fixed, because my students have to use the X and Y coordinates to calculate the RMSE of their Geo Coding afterwards and several students had problems with the unintuitive change of values.

Best regards,
Geo

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