Mapping areas with significant elevation changes vs drone altitude

OpenDroneMap Desktop
1

Hi All,
I am enjoying great success with WebODM for mapping fields/orchards, but I have difficulties when during mapping some area is considerably higher than the rest, while the drone altitude during mapping stays the same.
As an example, when flying the drone at 25M (I like low for extra safety), when the terrain had a 10M elevation change (so drone was 15 M above this part instead of 25M) the reconstruction there failed.
This is easy to explain - the drone moves at a constant speed, and hence the overlap ratio you get when the terrain is closer to the camera is lower than in other areas. One can cleary see it when looking patiently at the images.
This can easily happen when you have a row of tall trees (15M or so) separating two flat fields. WebODM could not over come this and reconstruct the second field, even though the tree area was very narrow .
My questions:

  1. Is there a way to make WebODM take this into account post processing so it will succeed?
  2. Any good rule of thumb about altitude vs terrain height variations to get a good reconstruction? I know I can go to 50M (higher is not allowed here), but I’d like to stay lower.
    thanks in adance!
    treeline
    treeline1659×979 402 KB
2

Some easy solutions,

  1. add overlapp for the whole flight and go for 80/80 or 85/85
  2. use terrain following … add a DSM/DGM to your flight planning, usualy restrictions refer to hight above ground not starting point
  3. do a sepperate flight in the higher areas with plenty of overlapp
3 Likes
3

Thanks,

  1. will slow down scan significantly/reduce effective scan area.
  2. Definitely a good idea, will require using more advanced S/W and planning
  3. Seems like the easiest one - I’ll just separate the field scans.
    thanks DvM
2 Likes
4

Mind if I ask how you, specifically, add DSMs/DGMs to your flight planning?
I’ve been using DroneLink for a few months and am looking to get some more control of my mission-planning.

5

you can do it using he flight planning in pilot2 (enterprise).

1 Like
6

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