Do you need to tag a GCP in every image in which it appears?

Do you need to establish the GCP ground/photo match in every image in which it appears?
Or is collecting it in one of the images enough to have it mapped by the pixel ray mapping into all the others?
If a GCP appears in 6 or 8 images depending on your overlap it seems silly to collect it in all of them if it is not necessary.

It can help to refine the reprojection. I used to make sure my GCPs were tagged in every photo for Agisoft and Pix4D, and manually adjusted them.

I would think you should target at least three images per GCP if possible.

I’m not sure if you need that level of precision, though.

So the pixel match between the photos is somehow affected if I don’t tag GCPs in all of them?
That doesn’t make any sense to me. Sorry.

No, I was referring to the refinement workflow Agisoft and Pix4D have for tagging GCPs.

We don’t have that (I don’t think), but I would still try to target at least three images per GCP, as per Pix4D’s guidance.

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That’s our recommendation too.

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