Working on a 3-mile corridor survey for a proposed road alignment. 200ft wide corridor. Flying at 250ft AGL with 75/70 overlap.
How do you guys handle GCP placement on long linear sites? Every 500ft on alternating sides? Or cluster them differently?
Also, how many checkpoints vs control points on something this long? I'm thinking 15-20 GCPs and 8-10 checkpoints.
Sign in to join the discussion
Sign inFor corridors I do GCPs every 300-400ft, staggered left-center-right. So roughly every 1000ft you get a full cross-section of control. Checkpoints every 4th GCP location.
With RTK you can cut this in half but with standard PPK/GCP workflow, more control = better accuracy on long strips where error can accumulate.
20 GCPs over 3 miles sounds about right but make sure you have them at both ends and at any elevation changes. Road corridors tend to have subtle grade changes that can fool the processing.
I'd go 18 GCPs and 10 checkpoints. The checkpoints are where you prove your accuracy to the client.