Corridor mapping

Imagine a corridor with a length of 20 km and a width of 400 meters, how many segments can you divide it into to keep the data quality high? How many GCPs per segment?

Imagine that there are no line of sight regulations, or imagine that you have been granted for BVLOS.
You are using a M300 with a L1 sensor over hilly to flat terrain, flight altitude 70 meters AGL, accuracy expected 7 cm on Z axes and 14 cm on XY.

Looking forward to hearing your thoughts.

The real question here is what your definition of “high” is. Do you have a desired point density per square meter?

Are you just trying to capture ground data or are you trying to capture structures as well? If so how tall are the structures?

What equipment are you using to capture the GCPs or would they be shot by a surveyor?

What type of GCP Aerial Targets would you be using?

Happy to help, just need some more info first.

Thanks for your interest, trying to reply to your questions:

  • point density 100 pt/m2

  • need to capture only ground data

  • GCP will be shot by a surveyor in RTK

  • Classic GCP, 40 cmx40cm chessboard-like

  • Accuracy 7 cm (Z), 14 cm (XY).

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Taken directly from this page Zenmuse L1 - Lidar + RGB Surveying Solution - DJI

“Over 30 minutes, at a speed of 13 m/s, a flight altitude of 100 m, with a side overlap rate of 10%, point cloud density > 100 points/m2.”
During that time 2 square kilometers were captured.

So with that in mind you should have no issues capturing at your defined parameters.

(20 km) x 400 m = 8 km²

Simple math:

30min per 2 km²

~2+ hour capture at 13m/s and 100m AGL w/ 10% overlap

You could estimate 3+ for doing it at 70m AGL

The one thing that I question from your post is the size of your aerial targets. That seems pretty small for those flight parameters. It might be worth using larger ones, or flying lower/slower when you pass those targets.

We just finished a 5 mile corridor in the middle of nowhere, Alberta.
We flew at 60m AGL with a speed of 8m/s.
This produced more than enough data for contours and engineered survey data for our client.

For GCPs, we shot 3- 5 points every 1/2 mile (virtual control) and we used two targets for alignment and position.

Mind you, our ROW was only 100m.

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Thanks for your reply,

can you give further insights about the following topics?

  • Did you use RTK or PPK for data correction?
  • Did you fly the corridor just at once or with multiple segments?
  • What was the maximum lenght of your segment?
  • What was the maximum distance from your base station?
  1. We use PPK for our data correction. It is the best method and the most accurate.
  2. For this particular job, I set up in the “middle” so I can fly out and back for each segment. For this job, the ROW was small enough that one pass “up” and one pass “down” captured all the data very well.
  3. The maximum length of a segment is as long as you want to make it. Consult your location’s flight regulations in regards to VLOS/BVLOS flight.
  4. Our max distance from the base station, for this flight, was 6.4km (4miles). You must watch the distance your “rover” goes from the “base”… there are limits! You will know you have reached these limits when your data looks like it is “delaminating” or you have multi-surfaces everywhere.
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