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Author Topic: Set ground control points in model or photos?  (Read 3448 times)

LCB

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Set ground control points in model or photos?
« on: July 06, 2017, 12:13:49 PM »
I see that it's possible to register ground control points both in the model and in the individual photos. Anyone know the difference between the two? It can take forever going through the photos, while it's fast and easy in the model.

Lars

Alexey Pasumansky

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Re: Set ground control points in model or photos?
« Reply #1 on: July 06, 2017, 12:20:07 PM »
Hello Lars,

You can place the marker on model and then review it's projections on the individual photos and adjust the projection, if necessary, manually. Doing that you'll see how accurate it model-based marker placement.
Best regards,
Alexey Pasumansky,
Agisoft LLC

SAV

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Re: Set ground control points in model or photos?
« Reply #2 on: July 06, 2017, 01:07:55 PM »
Hi Lars,

The placement of markers on the pictures is more accurate, hence I wouldn't do this on the model.

In case you are processing geotagged images (i.e., acquired by a UAV/drone), run the photo alignment first and then import the marker locations (both have to use the same coordinate reference system). This should place the markers very close to their actual location. Manually move them to their real location (matching the GCPs) and you will see that the 'flag' turns green. Repeat for each marker on 4-5 pictures. You don't need to manually adjust a marker on all images. Use the FILTER PHOTOS BY MARKER option which accelerates this step. Then run optimization (magic wand icon in reference pane). Don't forget to adjust the accuracy settings before running the optimisation though.

Hope this is helpful.

Regards
SAV