Contour Duplicate Lines when using Simplify?

[coreysnipes]

I’m seeing what appears to be duplicate contours when “simplify” is enabled (simplify > 0). It’s possible I’m just reading this incorrectly, but it looks like the contour function is rendering two, slightly-different lines at the same elevation.

I’m just viewing in WebODM orthophoto view. I have not tried exporting the data and viewing elsewhere. Dataset it Brighton Beach.

[coreysnipes]

I’m just looking for a sanity check on this, to make sure I’m not missing something obvious. I will file as an issue in github if I’m not being daft.

[smathermather]

That is odd and looks like a bug.

[uplanddog]

I tried it on one of my datasets with 1M interval and .2m (normal) simplify.

below on the interpolated area of the DTM there is plenty of craziness with lines splitting and overlapping.

However on the on the main area of the site, lines do appear to be normal.

[coreysnipes]

Cool, thanks for confirming guys. I will file in github.

[smathermather]

Corey: can you confirm you’re seeing this in the nearest neighbor interpolated portion of the elevation model like uplanddog?

[coreysnipes]

Checking this; I will report back.

[coreysnipes]

Added WebODM issue in github: Contour line duplication · Issue #1368 · OpenDroneMap/WebODM · GitHub

Some additional observations:

• Most easily observed near the edges of the ortho, but not always limited to that region. It’s not clear to me whether this is limited to the interpolated region. Possibly?
• Behavior seems to be limited to contours which do not extend all the way to the edge of the orthophoto region. i.e., drawing of contour turns back before reaching the edge of the ortho and continues drawing in the reverse direction

[coreysnipes]

Here’s some additional analysis from Paul Veisze @ American River College, who observed the issue and brought it to my attention.
WebODM Contouring Test.pdf (1.4 MB)