difference between geo-referencing by camera position and GCP?

[ahmed KIMOO]

hello,
what is the difference between geo-referencing by camera position and GCP?
thanks,

[SB]

GCPs are consistent coordinates across all photos.  All photos that have a GCP in it will at least use the same coordinates as the others.

Each time the phone, camera, or hand-held gps unit tries to determine gps location it is different, the errors are different, and it is simply unreliable.  A TotalStation or other survey equipment is the most accurate.

Even if you have incorrect gps coordinates, using the same data with GCPs at least prevents the error from compounding from one photo to the next.

Also, GCPs without coordinates are useful with aligning photos, making scale bars, etc.

[GPC]

SB's logic is flawed, although what he is saying can be true.

The GPS in your drone, most likely, is autonomously derived. The coordinates are most likely accurate to a few meters.

GCP, often, will be corrected through some means, either real time or post processed, to achieve an accuracy of a few centimeters.

It is possible to measure GCPs with your phone, which would be no better than your drone. Or your drone could have high accuracy gps. You just have to know what is crap data and what is good.. then use it accordingly.