Wow that looks very accurate, very small errors. I was looking at the phantom 4 RTK or the Autel Evo II but will likely start with a standard phantom 4 pro with no RTK to keep costs down. Is it challenging measuring accurate GCP and control point coordinates or is that something which can be learned with the proper GNSS equipment?The Phantom 4 Pro V2 is what I use for mapping and its mechanical shutter, 20MP, 1" sensor perform very well especially with dialed in Manual settings. I have a custom aftermarket PPK kit on the drone and also will use both PPK and GCPs but also just GCPs. My map with the best reported accuracy by comparison to control points was a small one with 5 GCPs and 5 Checkpoints, no PPK corrected images and the results were excellent. Actually I cannot state the mm level RMS error as in the X and Y horizontal it is slightly below GSD and accuracy cannot be under GSD.
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The Autel Evo 2 RTK or Enterprise with RTK module is a very interesting new solution. You are basically only NTRIP/VRS (Internet corrections) or a known point with an Emlid Reach RS2 (Also can act as a caster to send out its own NTRIP) away from adding GNSS accuracy.
It has a 1" sensor, long flight times, the ability to swap camera payloads (The connection is not meant to swap payloads an infinite number of times in my opinion) and a stated cm precision in both RTK and PPK workflows, with the PPK workflow using a produced RINEX file.
A sister forum member JMason has been conducting some really interesting tests with this unit and the results have been very good. I am in no way an image expert, but I have read that Autel does a much better job in converting images to JPEG format and that many people claim that this helps with more points in your photogrammetry derived point clouds. It does lack a mechanical shutter which would enable you to conduct missions at a higher speed and help prevent the roller shutter effect, but the desktop applications like Pix4D and Agi Meta both have algorithms that can deal with it. You could also fly at a lower speed, but I would personally like to read more about others experiences and tests.
Link to Evo 2 RTK tests on sister forum. He has several threads on different tests, including thermal mapping and is a wealth of information on this new drone with his tests that he posts for all members to view.
one manual flight and one Shutter P flight. Both 150AGL, 80/80 overlap, 7MPH, 120 photos, same flight with one point. the point was not used on the DD report and it costs $50 per map to add points. MS has the point. Very Impressed with the results.autelpilots.com