Markers with fewer than three coordinates (x,y,z)

[lefsky]

I am working with historic aerial photography from heavily forested areas where it is often difficult to find ground control points. On the one hand, I can use photo coordinates for that purpose but I don't have vertical coordinates for them (although the terrain is relatively level).  I'd also like to be able to use markers to indicate that points on two photos are at the same elevation, even if I'm not sure of the absolution elevation.

I know that specialized photogrammetric programs can do some of this, but I don't see a method in Photoscan.  Does anyone know if it can be done and if so, how?

[Alexey Pasumansky]

Hello lefsky,

All three coordinates should be input for marker to the Reference pane, however, you can lower the accuracy with which those coordinates would be treated: use Set Accuracy option from the context menu in the Reference pane for marker or several markers and use "slash" separator to input individual accuracy for each coordinate, for example: 10/10/1000 - it means that for X and Y the accuracy would be 10 meters and for Z - 1 km. The same values can be input as 10/1000.

[tutoss]

wow, that is useful, it will be in the GUI, no "hidden"

[n@sk]

Bear in mind though that even if the corresponding residuals are ignored, the input coordinates will be used to initialise the bundle adjustment; if you use many such points and the elevation is unreliable, they will dominate the process and converge to a useless solution.
In any case this will not work for the elevation equality constraint.
I do not think that this is how the other "specialized photogrammetric programs" go about doing this.

Just a reminder of a feature request:
http://www.agisoft.com/forum/index.php?topic=7718.0

regards