We have a project where 1) the circumstances make it prohibitively expensive to use GPS equipment to collect GCP coordinates, and 2) we have no need for georeferenced outputs.
We’re only going to be using the orthomosaic to draw linework, no elevations needed.
The plan is to collect the coordinates for the GCPs in an arbitrary coordinate system, but I see that the AutoGCP functionality does not support arbitrary systems.
I was thinking maybe I could download some georeferenced satellite imagery of our area of interest, and “transform” our arbitrary coordinates so that the GCP coordinates approximately line up with their real-world locations. My understanding is that the absolute accuracy of those “transformed” GCP coordinates would be terrible obviously (or unknown at best), but the relative accuracy should remain unchanged, correct?
The only thing I can think of is that the Quality Report might show some very high error values in the geolocation section, but I’m wondering if that actually matters when we aren’t concerned about georeferencing the outputs.
I’m planning on testing this idea using a georeferenced dataset that we already have good outputs for, and then comparing the results. I was going to take the GCP coordinates (collected with GPS) from this old job, and just shift/rotate the points slightly in CAD to simulate me “faking” projected coordinates, then export the “faked” coordinates and try to process the dataset again.
If anyone else has tried this before or actually knows enough to know that it won’t work, please let me know! Maybe I’m not seeing an obvious flaw in this plan lol. Thanks!