Error in GCPs with regards to Historic Airphoto

[matson]

Hello,

I am currently trying to generate a DEM from historic air photos. I am currently following the "Orthomosaic and DEM generation with Agisoft PhotoScan Pro 1.3 (with ground control points)" tutorial online, but I am having difficulty when it comes to referencing the model with GCPs. At first the GCP referencing worked in my first model with minimal errors. I could generate a DEM and the orthophoto looked great. Then I tried again with multiple models including the first one again and I am getting average errors of about 1000 meters with upside down DEMs and dense point clouds that don't look like the model. Some things to note:

I am getting my coordinates for the GCPs from a LiDAR image (UTM zone10)
I do not have any flight path to reference the cameras because they are old orthophotos, so I am aligning the cameras based on the points Agisoft recognizes from the images, and the GCPs
Prior to uploading the coordinates the model looks good and if I generate a dense cloud or orthophoto without the GCPs the model looks great
I used the same coordinates when re-trying the first model

Any help would be much appreciated!

Thanks,
Kelsey

[Alexey Pasumansky]

Hello Kelsey,

Probably the coordinate information for some markers has been mixed up. You can leave only a few markers checked on in the Reference pane, then press Update button on the pane's toolbar, and if the model is oriented correctly, then look on which markers in the pane the large errors are observed.