Help in identifying fiducial position Fairchild camera

[danielf]

Dear Metashape users,

I am processing some very old historical aerial photos, and while I have the fiducial mark coordinates, the calibration certificate is too schematic when showing the exact position of the fiducial marks. I could not find any similar examples on the internet. Have you come across these fiducials as in the attachment and do you know where to flag them?

[JMR]

I think Fairchild fiducials used to be a white small dot inside the outer black frame in the center of each side. The additional dents closer to the corners are intended for srinkage control.
Regards

[danielf]

I think Fairchild fiducials used to be a white small dot inside the outer black frame in the center of each side. The additional dents closer to the corners are intended for srinkage control.
Regards

Thanks for your feedback. Yes, I have seen those fiducials elsewhere, but my photos don´t feature that type of fiducials. NO small dot there.

[vineg]

Hi!

Metashape can detect middle poins of black exterior frame as an artificial fiducials. It is not that accurate, but may help to process dataset alongside with autocalibration.
It is available in Tools menu -> Markers section -> Detect fiducials -> Detection type: Frame

Egor

[danielf]

Hi!

Metashape can detect middle poins of black exterior frame as an artificial fiducials. It is not that accurate, but may help to process dataset alongside with autocalibration.
It is available in Tools menu -> Markers section -> Detect fiducials -> Detection type: Frame

Egor

Thanks for the suggestion Egor.

Unfortunately the automatic detection of fiducials doesn´t work at all in my case. Photos are very old and not in the best preservation quality.

[vineg]

Hi!

You can place fiducials at the tip of a triangle at the top and the black triangle at the bottom of the image and either at the tips or at the lower base of the middle triangles from the sides.

It is worth to try alignment on the part of the project first.
And if it is incorrect positions, you can still run Calibrate Finducials like an article suggests:

https://agisoft.freshdesk.com/support/solutions/articles/31000159531-processing-scanned-images-with-fiducial-marks

If there is no camera certificate with fiducial marks coordinates information for the data set in question, then it is necessary to Calibrate Fiducials. For the purpose in the Camera Calibration dialog box run Calibrate Fiducials... command from the context menu of the selected images. All the images from the respective calibration group should be selected.

Egor