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Author Topic: GCPs with no elevation value?  (Read 2734 times)

jazzyj

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GCPs with no elevation value?
« on: May 03, 2019, 10:50:17 PM »
What if I have only X/Y values for my GCPs and no elevations values?  How do you incorporate those?  (I'm only needing to build a 2D orthomosaic map.)

Can I click "Add Marker" at the GCP in the photo and then just edit the X/Y values to correct the coords and thereby default to the elevation value in the photo?

JMR

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Re: GCPs with no elevation value?
« Reply #1 on: May 06, 2019, 04:02:06 PM »
You can add GCP with XYZ using precise XY and guessed Z taking it from google earth, for example, then set accuracy accordingly, for example an accuracy of 0.005/10 would mean 5mm in horizontal positioning and 10 meters in vertical.
Also, if you are using a drone geo-tagged images, you can use 10/10/0.2 for camera accuacy. So the drone altitude measuered by the baro altimeter (which is often quite accurate in relative) will make your model to be properly leveled while GCP will put it into right XY

Regards

jazzyj

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Re: GCPs with no elevation value?
« Reply #2 on: May 06, 2019, 06:13:55 PM »
The workflow published by Agisoft has the user uncheck all photos and only check the GCP markers when performing camera optimization.  It seems to me, this may be recommended if cameras have no geolocation data in the EXIF?

What about this workflow?

Use "ADD Marker" function to identify visible GCP in one photo.

Edit Marker X and Y coordinates to correct, do not edit Z (altitude) as it will use altitude from EXIF in that photo which is a good estimate within 10m.

PLACE Marker (with corrected X Y coordinates) in at least two other photos

Optimize cameras (which have geolocation in EXIF) with photos and markers checked?  Or optimize with only markers checked?

There are SO many options (check boxes) on optimize cameras screen. Which ones to turn ON/OFF?