hey there.
When measuring roofs with a non-RTK drone using GCP’s in a PPK workflow, what is the best practice, where to put the GCP’s? I did some non-roof related measurements and I always put the GCP’s in the corners and in the middle - depending the area sometimes more than 5. But with roof measurements, I can’t put them on top of the houses 
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Sounds like a great excuse to get an octocopter and drop your GCP mat on the roof 
This is a fascinating question… I’m imaging that the four corners of the structure would likely help, even without one in the center.
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Not sure if its a silly question, but if you have to go on a roof to place GCP’s then why not just make the measurements of roof while up there?
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