How to interpret accuarcy/errors if there are no markers/GCP's

[MoWo]

Hi guys

I am not an expert in aerial photogrammetry, so I have a question about the accuracy and error values given by Metashape.

I have a composite of overlapping aerial photographs. Each image has meta information that can be used for referencing (i.e. timestamp, easting, northing orthometric height, omega, phi, kappa, lat, lon).
I load the images in my chunk, import the reference file, and then run MatchPhotos/AlignPhotos. There are no GCP's or markers for my data.

I read in another post (https://www.agisoft.com/forum/index.php?topic=6271.0) that the error sizes should be interpreted as follows:

X, Y, Z error (m) - difference in the corresponding direction between source (measured) value and estimated by PhotoScan for marker,
XY error (m) - planar error for marker,
Total error (m) - the distance between source and estimated location for marker,

But how should I interpret the accuracy and error values if there are no measured values/markers?