Various Improvements / Feedback

I've tested the interface, so far I've found these issues (tested on Chrome):

Dragging control points around the left panel, when zoomed in, makes them disappear as soon as they are dragged.
Dragging control points around the left panel, when zoomed out, does not align with the position of the pointer.
Once a point is added to the map, and a new point is being edited, the previous point cannot be interacted with (perhaps this is by design?).

Also these things perhaps could be improved from a user experience perspective:

Make left panel larger (at least 40% of screen), so that it's easier to navigate the images.
Avoid having to manually press the "Ground Control Point" link/button to add a new ground control point. Clicking on an image, where there is no existing GCP, should automatically add a new point.
Instead of having buttons on the left side panel to add/delete GCP, clicking on an existing GCP should bring up a dialog/popup (leaflet style) with options to delete/interact with the GCP.
Consider using left mouse button to add/drag around a new GCP, middle/right mouse click to delete a GCP. Dragging a GCP outside a picture/map could also be a way to remove a GCP.

OpenDroneMap / posm-gcpi