Michael,
Very helpful, thank you very much! Have you ever used OPUS…if so, is it reliable and accurate? thanks again!
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I have used OPUS and it is great but I prefer NRCAN. For whatever reason they seem to match what our network says better. They do use GPS and GLONASS instead of just GPS so that may be part of it. They also use the Rinex data rate whereas OPUS uses a 30-second processing. I don’t know if that really matters when you’re collecting a point for a couple of hours but I bet it sure cuts the data they have to deal with down. Either of those solutions are as good as you are going to get with GNSS for absolute global positioning.
Since that term came up think about what kind of accuracy you need. In my experience there are 3 methods of rectifying drone geographic information. The first would be just relative accuracy. If you are doing something like a construction site that just needs progress and map overlays you probably don’t need to integrate with their coordinate system. In that case you could just single-average in a point and manually set to it every time you come out. Your data would be relative to itself each flight and there is quite a bit of good you can do with that scenario.
The second would be when you do need to integrate with their coordinate system. For this you would need to get control from them. They may be on a formal coordinate system but my experience in the US is that there is always a localization or site calibration that manipulates the coordinates just enough to throw the data out of tolerance in alignment. This can also apply to when you are working with a Registered Surveyor. You just need to match their data. The good part about this scenario is that Surveyors use Grid or Surface coordinates that you drone data can be directly transformed to instead of some arbitrary shift like you would see in construction.
The third would be the absolute global positioning where you need to either PPP or have some other official source of data tied to your region’s geodetic society. In the US it’s NGS. Sometimes I can get lucky and have one of their benchmarks nearby but a lot of my work is out in the middle of nowhere so I either Reach 
the network, PPK the network, PPP or get control from someone else.
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Thanks Michael…all great info. I realize I have a much to digest and learn…
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