Improve rendering of pine forest in orthomap?

[Totallygatsby]

I love the results I get from the orthomap and OpenDroneMap in general, but I’m finding that the pine trees in my mountainous area tend to resolve a bit more… impressionistic and swirly than pines.

Here’s an uploaded example:

High level orthomap:

High altitude photo.PNG

Point Cloud:

Point Cloud.PNG

What I’m wondering is what I should be tuning or testing to improve how the trees look.

My current settings with the ~570 photos I took (which I downscaled to 4000px).

Options: dem-gapfill-steps: 6, dem-resolution: 2, dsm: true, dtm: true, feature-quality: ultra, mesh-octree-depth: 12, orthophoto-kmz: true, orthophoto-png: true, orthophoto-resolution: 2, pc-quality: high, pc-rectify: true, pc-tile: true, rerun-from: odm_postprocess, tiles: true, use-exif: true
Average GSD: 2.54 cm
Area: 412,877.31 m²
Reconstructed Points: 46,354,467

Improvements I think I’ll need to make:

1. Fly a more even grid (I’m flying my Air 2S manually because there’s no automated flight planning tools yet)
2. Point the camera at -80 or -85 rather than -90 degrees
3. Fly multiple grids, offset at 20 degrees (I flew one grid)
4. Adjust the altitude of the drone as I go up/down over areas (the terrain is quite mountainous, I thought I needed to keep a consistent height above sea level, but consistent height above ground might be better?)

But other than improving the flight characteristics, what settings should I mess with to try and get cleaner looking trees in the orthomap?

Also, any tips for mapping hundreds of acres of mountainous forests?

[Gordon]

@Totallygatsby

Adjust the altitude of the drone as I go up/down over areas (the terrain is quite mountainous, I thought I needed to keep a consistent height above sea level, but consistent height above ground might be better?)

If you fly at a constant altitude above sea level but the height above ground level varies significantly, you’ll end up with areas of smaller GSD but insufficient overlap, and other areas with larger GSD but more overlap.

Trees will look very swirly when it is windy, as they move between images, especially around the outer edges of the foliage.

[Totallygatsby]

Yeah, definitely something I’ll keep in mind for next time. In this case, the day was pretty still – not much wind at all. (There was probably some, but I don’t recall having to pay attention to it as my flying position was pretty exposed.)

[pierotofy]

Try:

--use-3dmesh --mesh-octree-depth 6

[Saijin_Naib]

If you have the processing capability, maybe up --pc-quality a notch as well as what was suggested above?

[Totallygatsby]

Will do! I’m pushing into the upper limits of my 40GB of RAM on my box, but maybe I can split and merge (though, when I tried that last time I ended up with a point cloud that had three distinct layers at differing altitudes).

[Saijin_Naib]

I’ve seen nicer tree reconstruction with --pc-geometric, so maybe test that first?

[Totallygatsby]

Will do, though when I tried that it crashed with a message about a missing ply file? (I’ve lost the logs.) Could just been a transient failure though.