Yes- if you're using "REFERENCE" without lat/lon it would probably confuse Photoscan no end - I missed that
Good catch, Stihl
And upon further review, I take back my suggestion about manually setting the altitude to the known mission height.
If you had lat/lon values, as in from EXIF, that would help, but since you don't, you would have to create an import file that includes lat/lon and altitude.
If there is a way to only set ALT and leave Lat/lon unknown I don't know how to do it.
Which means you would have to set the lat lon values to zero or some estimated value.
Having the lat/lon for every image set at 0, or even an estimated value would probably confuse Photoscan more than the good that you would get from having a set altitude value
From the shape of your turns it look like you're using some sort of fixed wing platform?
No hope of a flight log with Lat/Lon/Alt?
I recently came up with a way to extract the gimbal directions for every image based upon it's time code as compared to the associated values in the flight log file of a Phantom Pro 3. In addition to pitch and yaw, I also can get more accurate lat/lon/Alt values by interpolating between flight log entry lines than seem to come in from the P3P EXIF values.
Once you include pitch and yaw, as well as increase the accuracy of the Lat/Lon/Alt values, you don't have to delete the cross-grid first and last leg images anymore, and everything stitches every time.