Getting conflicting info on this. Some people say RTK means you don't need any GCPs, others say you still need them. Just did my first RTK flight on a 40 acre site and didn't use any ground control. Results looked good but now I'm second guessing myself.
What's the actual best practice here?
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Sign inOK this is my favorite topic so buckle up.
RTK gives you accurate camera positions. That's it. It doesn't magically make your photogrammetry perfect. You should ALWAYS use checkpoints to validate your results, even if you're not using GCPs for processing.
My workflow: RTK flight, then I set 3-4 checkpoints (not used in processing) to verify accuracy. If checkpoints are within spec, I'm good. If not, I know something went wrong.
For client deliverables where accuracy matters, I still use 4-5 GCPs on a 40 acre site plus 2-3 checkpoints. Belt and suspenders.
40 years doing this with total stations and chains before that. The fundamentals haven't changed - always have independent checks on your work. RTK is a tool, not a magic wand. Trust but verify.
Anna's right about checkpoints. The thing people miss is that RTK reduces how many GCPs you need, it doesn't eliminate the need to verify.
For internal use or progress monitoring? RTK only is fine. For deliverables going to a client or engineer? Use checkpoints at minimum. For legal/boundary work? Full GCP network, period.
One thing nobody mentions - RTK accuracy depends on your base/network. If you're using NTRIP and your connection drops mid-flight, you might not even know it. That's why PPK is sometimes better for remote sites. At least you can verify the corrections were applied to every photo.
Checkpoints catch these issues. Don't skip them.
@NewbieNate I use 12" checkerboard targets from Amazon. Like $30 for a pack of 10. Spray paint works too but targets are easier to pick in the photos. Just make sure they're visible at your flight altitude.
This is super helpful. So for my subdivision work where I'm tying into existing control, sounds like I should be setting a few checkpoints to verify even if I'm not using GCPs in processing. Makes sense.
How are you guys physically marking checkpoints? Painted targets?