Contour units

Hi All

Quick piece of advice please? So i have 3 separate drone data capture jobs. All are similar in that I’m flying about 240 - 300m above ground, taking images that overlap by 80% or so etc.

All process sweetly in ODM, ortho looks great, 3D looks great.

When creating contours, two of the jobs return data that looks about right (ie im expecting elevations of 350, to 400m above sea level and thats what I am getting). The third job is returning strange numbers that range in value from -9 to +8m. The site is reasonably flat and a 20m variance would be about right, but above sea level should read about 90m.

Ive processed them exactly the same. Ive also looked at the EXIF and they all contain the same info, as I would expect as I have used the same drone (P4 Pro II).

Any ideas?

Cheers
Tony

1 Like

Sorry I don’t really have an answer as to why. I’ve seen similar results though.
I find the only way to get reliable vertical results is to use ground control points. M

I’m surprised by that lower job, too. Any chance you could share some photos from each job? Maybe there’s something non-obvious in the EXIF. A few extra community eyeballs might help identify a pattern.

I have attached 4 files.
2 from a successful contouring export (prefix “good-”)
2 from non-successful (prefix “bad-”)
good-DJI_0018

I have attached 4 files.
2 from a successful contouring export (prefix “good-”)
2 from non-successful (prefix “bad-”)bad-DJI_0688

PS Ive only attached one of each as I’m not allowed to attach more than one file.

Tonyshep,

what if you create at least 5 GCP??
I’m sure there are sources of elevation data in yout country. Maybe you can use google earth data.

Regards