Align with GPS coordinates: should images be checked or not?

[FIFER]

Hello,

I have a big dataset of images (>26k) taken with a lawn mower pattern and roughly facing down.

I have estimated the GPS position for the majority of them and imported it in the hope to speed up the alignment.

To do so I understand I need to set the Reference preselection to "Source". However it is not specified if the cameras with the GPS coordinates need to be "checkec" or "unchecked".
I have been taught to leave images, markers and scale bars unchecked images  before Gradual Selection for Reprojection Error, and thus not during alignment.

So, I am wondering if the position of unchecked images is still used to speed up the matching and image pairing during alignment with preselection set to Source.

Otherwise, Should the cameras be checked during alignment and then unchecked (to avoid constrainig) during the first steps of the gradual selections?

Thank you
Filippo

[Alexey Pasumansky]

Hello Filippo,

For the reference preselection is does not matter, whether you have cameras checked on or unchecked in the pane - the coordinates from the source values tab of the Reference pane will be considered in any case. But it is important to have coordinate system properly selected in the Reference pane settings dialog to fit the coordinate values input for the cameras.

In case the coordinates of the cameras are more or less correct (according to the Accuracy value), you can leave the cameras checked on, in this case the result of the alignment will be also referenced in the selected coordinate system. Otherwise you would need to check on cameras or markers and press Update button to apply the Referencing prior - this is suggested prior to applying the gradual selection filtering or running optimization.