Alexey,
Thanks for the reply. Hitting Update then Build Orthomosaic still doesn't let me select geographic. If I select all the cameras then update they do show up, but I'd like to use the marker data rather than the camera data... as the camera data is quite inaccurate.
I haven't bothered much with altitudes and didn't seem to notice much of a difference in the output. I'm not necessarily interested in any DEM or models, just really stitching many photos together and georeferencing the result. But I can try adding that information if it'll increase the quality of matching.
Could I use the altitude from a tool like
http://www.mapcoordinates.net/en for the markers and then that number plus estimated flight altitude for the camera altitudes?
Thanks!
Kevin