Hi Anders !

Don't know if you'll see this answer somehow, so I'll not make a long and detailled one

I have thinking about calibrate our DJI Phantom 4 Pro UAV before handle surveys. But

*there is a huge problem*:

The calibration should have been made with

**exactly the same parameters than the survey will !!!**So, as you have to always take pictures (your whole survey) with

**exactly the same focus** (basically with UAVs, focus on infinity for lots of surveys), you have to calibrate your camera while focusing on infinity...

And, with a simple calculation of depth of field, you quickly understand your calibration has to be made more than 10-15m far from your chessboard...which is ensuing a huuuge chessboard

As a conclusion, I would say your calibration will be almost useless as it looks you took pictures only a few meters far from the chessboard, and maybe in autofocus.

And there is the moment I may need help:

**How to calibrate that kind of cameras ?**I've thinking about handling a georeferenced survey of an ideal place (ideal for matching) with autocalibration, and then iterate the alignment while using calculated camera parameters...

Have somebody even handle that ? Or have another solution to calibrate cameras focusing on infinity ?

Thanks