Step in elevations?

Data Processing - Discussion and Q&A
1

I’ve just processed a fairly large map of a Tailings storage facility. I just wanted volumes of stockpiles around the edge, so left a gap in the middle, leaving a ring shaped map area.

It all looks great except there is about a 5 m step in the contours on one side.

Could this be caused by the stitching working its way around the ring building errors and leaving a step when it comes back to the start point?
I will try again with a gap in the ring.
Any way to avoid this happening other than leaving a gap?

2

Could you share a link to the map?

3

It is this one
http://www.dronedeploy.com/app2/data/5a867c7d3c15b832f2a4bb56;jwt_token=eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJ0eXBlIjoiUmVhZE9ubHlQbGFuIiwiaWQiOiI1YTg2N2M3ZDNjMTViODMyZjJhNGJiNTYiLCJleHAiOjI1MzQwMjMwMDc5OX0.R3xZZqgE6FL2hYJ2CVBrFZWCvoBjOhy9g7I9eo5Cw1r9uk35Iepm2pxgGYElVxS5pRijQ7IzoymomhitLWHj-g

The step is to the northwest

1 Like
4

I tried again with a gap, and it doesn’t have the step in that spot.

http://www.dronedeploy.com/app2/data/5a88436efdee656e5a4c4c06;jwt_token=eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJ0eXBlIjoiUmVhZE9ubHlQbGFuIiwiaWQiOiI1YTg4NDM2ZWZkZWU2NTZlNWE0YzRjMDYiLCJleHAiOjI1MzQwMjMwMDc5OX0.RruDMLHNV1AH2uRr46gtoAQzJQf9ZY-hZK21Y6u-Z6Z8dqTsYceB-t2zUigFsOBiv_lDhtZRRA4QN3337As6gg

1 Like
5

What does your flight plan look like? Was it setup in DroneDeploy or maybe manually in another app? This is a very interesting one!

6

I did it as 5 separate flight plans with the same parameters, If setting it up as a single plan it kept wanting to map the water in the middle, which I didn’t have time for. It really looks like it has stitched the images around in a circle and ended up with a discontinuity when it reconnected, which I can see being a problem with any ring shaped set of images.

I used the dronedeploy app, with import kml/shapefile plug in.

7

I have never seen anything like that before for sure. I have flown sites over several days in different rows and columns without much noticeable merge lines at all. Especially strange since cutting the loop fixes the stitch.

8

Hi @Michael_Dufty,

If the Kml/shapefile is a complex shapefile we do not have the logic to adjust the flight parameters to exclude one or the other. By complex, I mean a polygon within a polygon. If you would like to crop out part of the geotiff this can be done within QGIS by using this tutorial. Please let us know if we can help with anything moving forward.

9

The kmls were simple polygons, I just used 5 of them to make 5 separarate flights to get the ring coverage.

I don’t mind the inner part of the ring being mapped, just didn’t have the time to spare on site to fly it all, when it is just water anyway - doesn’t give useful information, and doesn’t produce proper elevation results.

10

At what point to the east does the bad map tie back in to proper grade? Is that whole section one of the flights?
If you take out a different section does the map still look good or is it just that section removed make it work?
Were all the flights done on the same day?
Can I message you so you can upload your images to me?

I’m super interested in this case now! Thanks for posting.