Hi everyone,
We’ve been testing the use of ODM to process DSM from fixed wing drone imagery on a low-lying barrier island environment. Images were collected with a fixed wing ebee drone equipped with RGB camera. We are running ODM through docker on a linux box and everything seems smooth there.
The images are of an undeveloped island with elevations ranging from 0 (shoreline) to about 3-4m dune heights into a somewhat vegetated back barrier but it is fairly sparse. We do not have visual GCPs (no fixed features on the island) but we do have a few on-the-ground survey points taken with RTK-GPS a few days before/after the drone flight that we are using for verification. Only 8 points in two lines from shoreline to the dune so they aren’t well-distributed. We also have a previous DSM for two of the flights created with pix4D that we are comparing to for reference.
We first used ODM with defaults but then (one-by-one) changed the following based on looking through this community:
ignore-gsd: true
orthophoto-resolution: 3
dem-resolution: 3
camera-lens: brown
Those settings gave us our lowest error but our elevations in the DSM still have a mean offset of 16 cm from the sampled points and the pix4D DSM. My next thought was to test the sensitivity to the smrf parameters but I was curious if anyone has worked in these types of environments and has a recommendation for optimal settings. I searched around but may have missed previous posts.
I put a small example of the orthophoto here: Dropbox - masonboro_orthophoto.PNG - Simplify your life
and a difference map of odm-pix4D here: Dropbox - odm_minus_pix4d.PNG - Simplify your life
We aren’t worried about waterways behind the island, our focus is on just the main part of the island. I also don’t expect the differences with pix4D to be zero everywhere – each program has their advantages but we may not have access to pix4D moving forward and I want to be confident I am getting reasonable DSMs with ODM.
Sorry for the long-winded post, any suggestions appreciated!