Drone recorded incorrect elevation value in the EXIF data, Having difficulty building 3D model

#1

Docker on Win10, Chrome

My drone recorded incorrect altitude data in the EXIF info (I fly Autel Robotics and I currently have an open support ticket with them for this). I am trying to generate a 3D model. However, WebODM is having difficulty building the entire model. The task completed but the resulting 3D model was only the bottom 3’ of the object. Issue #497 may also have relevance here. My best guess is that the incorrect GPS altitude EXIF information is throwing things off during processing.

These are the steps I took: open WebODM, uploaded images (find them here: https://drive.google.com/open?id=1g9IQ_caq9sVVeE6N0MuievcDWzqii27x on Google Drive), select the 3D Model preset, start processing.

Side note, I’m only trying to capture the front of the sign not the back. If there is a better way to capture the images please help me out.

Thanks in advance!

#2

First thing I noticed about the dataset is that there’s a lot of sky in the photos. I’ve never had good results with a lot of sky in them. I also don’t think there are enough photos of this to make it perfect, but we’ll see how we go.
I pumped this through the servers with a handful of presets that I have and the best one came out like this (see 3D tab): https://dashboard.aerosurvey.co.nz/public.cgi?S=320&T=31597698-0dff-45be-9a32-4a7f281139a9

Options: fast-orthophoto: false, use-hybrid-bundle-adjustment: false, use-fixed-camera-params: true, resize-to: -1, dsm: false, dtm: false, crop: 10, use-3dmesh: true, dem-resolution: 2, orthophoto-resolution: 2, depthmap-resolution: 2000, opensfm-depthmap-min-patch-sd: 1, min-num-features: 18000, matcher-neighbors: 0, texturing-data-term: gmi, use-opensfm-dense: true, mesh-size: 600000, mesh-octree-depth: 11, texturing-nadir-weight: 16

The textured model has a few holes in it, so the scene could benefit from more photos I think. I don’t think the altitude makes that much difference for 3D models; at least not that I’ve noticed.

There are some tasks that haven’t finished processing yet. I’ll keep going until I get what I think is as good as it can be.

Also those overhead wires look tantalisingly close on the map!

#3

@ITWarrior

Thanks for the help! I will shoot this one again and will keep the sky shots to a minimum. I felt pretty good with regard to overlap horizontally and vertically, but next round I’ll try to get more shots. And yes, the wires were very close, including the service drop to the sign itself. I had to fly carefully man.

I figured that the software should stitch the images together regardless of the altitude value, but I really couldn’t explain the results I was getting. Your result was much better than what I was seeing.

I really appreciate the time you took to check this out. Thanks for the insight.