Concerns about camera calibration

[birdofprey]

When I load into PhotoScan a set of photos taken by a Phantom 4 during a photogrammetric flight, just the NA symbol appears while the NC symbol does not appear.

I assume that the NC symbol does not appear because each picture already contains all the calibration data in the form of EXIF DATA. Its right ?

So... in this condition can I simply proceed to "Align Photos" and to "Build Dense Cloud" without entering in calibration menu or doing manual stuff about calibration ? Why if I do so, in the final report, in the Survey Data tab, "Precalibrated" field is marked with NO ?

[Alexey Pasumansky]

Hello birdofprey,

NC mark indicates that PhotoScan wasn't able to extract sensor pixel size and focal length from the image EXIF header.

Precalibrated label appears in the report when you input or change the initial tab values in the Camera Calibration window. Otherwise the initial parameters are automatically recalculated from the EXIF - actually, only focal length is converted to pixels, while other values are set to zeros, when Auto option is used.

[birdofprey]

Thanks for the reply.

So, in my case, PhotoScan can extract the data it needs from the photos and then all calculations are automatic... so, I have to do nothing inside the calibration menus.

Correct ?

[birdofprey]

I've read several old topics on this issue.

The common conclusion (especially for a "consumer" UAV such as the Phantom) is to avoid any pre-calibration process and take advantage of the calibration that the program performs during the alignment of the pictures.