Coded Targets as Markers in Aerial Surveying - Exxperiences?

[photogrammetrix]

Hi everybody,

we use coded targets as standard in close range photogrammetry, for which they work also fine in PS.

But I was wondering, if they may be also usefull  - time-saving - in aerial surveying with UAS and UL aircraft up to mid altitude like 700 to 1000 metres a. Gr.

I ran some simple tests with a 12 bit scheme and came to the conclusion that the coded targets should be imaged at least with 40x40 pixel, otherwise they are not recognized by the search algorithm.

Can somebody confirm this or has other experiences?

Thanks