Adding a step in a surface

Hi guys
I’ve got a site model for an architectural site with a terrain that I’m happy with. The problem is I need to input a step in the middle of the site which means refitting the terrain around it. Is there anyway to refit the terrain surface around this step that maintains the terrain’s smooth curvature? I’ve tried trimming out both sides of the site so that I can then use merge surface to refit the terrain of both sides of the site to join to the top and bottom of the step respectively, however this produces a result with a lot of kinks. If anybody knows a better way of doing this it’d be a huge help, I’ve added photos of the original model with the terrain unscathed and the step running through it and the attempt to merge the surfaces between terrain and step. Thank you.

Hello -I think you can do this - please post a file with just the surface and the new step, I’ll see if I can sort out a good way to do that.


Hi Pascal,
I think the file is too large to upload, I’ve tried but I get a message saying I’m limited to a few thousand kB. Is there some way I can share it?

Hello - please export the two objects to a new file, using the SaveSmall option and then if it is still huge, upload here, to my (Pascal) attention.


Think that’s worked, thank you for your help. If you do figure this out can you let me know how, I’m probably going to run into these problems in the future

step problem small.3dm (331.3 KB)

Hello - see if this is on the right track - (I cannot tell what you mean to happen at the end of the wall that does not taper into the larger surface )

step problem small_Maybe.3dm (465.3 KB)


that’s perfect, at the point where the wall tapers it joins to the wall of a building so I think at that point the step only really needs to join to the terrain at the bottom because the building will cut through the top part

This might help to illustrate

Hello - I guess you can trim it back like so

step problem small_Maybe.3dm (459.5 KB)

In any case, the process is to extract isocurves in an oversized piece ‘behind’ the wall, trim these to each other and then trim the surface:

Then use the trimmed edges and the curves (DupEdge) from the top of the wall to make a Patch surface.

as input to `Patch’, then trim that surface back:


Thank you Pascal, that’s a lot better. Thanks for your help that’s saved me so much time