Terrain from Contour Lines Spikes


I have been methodically tracing and separating contours to create a terrain but when I use DRAW-SANDBOX-FROM CONTOURS to make a terrain I am getting these strange spikes (which are surely in the original contour lines but its hard to find them…) Any suggestions!
Feb-21-2022 TOPO

Hard to tell from just the images. Can you upload the SketchUp file (.skp)?

If it’s too big for the forum (more than about 15MB) upload it to a file sharing service like Dropbox or OneDrive, and share a link here.

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Looks like from your screenshot you have some tiny stray lines above your contour base. Delete those and re-run Sandbox and you should be good.

There are also other extensions like TopoShaper that might work as well or better than Sandbox depending on your needs. Good luck!.

Thank you! I found those two points you found - thx!! and it helped but I can’t find many more… I can’t find other lines, even hidden lines… would Toposhaper bypass those ? Thanks!

Is there a way to manually edit out those spikes in the final terrain without having to go back to the original contours?

You can try to move the endpoint at the top of the spikes with the Move Tool.

The Move Toll is used to move a selection but, an endpoint cannot be selected prior to selecting the Move tool. The trick is that, if nothing is selected, after you select the Move tool, hover your cursor over an endpoint and then click the left mouse button (LMB) to grab it. Keep the LMB down and then move the endpoint down to level it with other points that are at the correct elevation.


Jean is correct! That is what I do when I get a spike like that. It’s typically drafting error on the dwg file. I have one surveyor in our area that almost always has this issue. The ones using 3D civil never do.

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Thank you!!! This is working. I really appreciate your help.