When you position a marker it turns green and photoscan's inferred position (grey flag) disappears. I would like an option to leave it visible or some other way of showing the disparity i.e. error bars, numeric x,y pixel error etc.
If I am right in thinking (in my ever simplistic way) that the error values shown in ground control are based on the difference between where the markers have been placed and where photoscan thinks they should be, then it would be really useful to know where it thinks they should be.
Sometimes I stare at a project far too long trying to work out where an error is originating from and eventually realise it is because I put a marker in a stupid place. Most of the time photoscan's estimated positions are more accurate than me!
Maybe this is because I vary rarely work with printed targets and more often building features that are surveyed using scanning and total station so is too easy to put markers in the wrong place...