2D curve draw on a 3D mesh terrain

Hi all,

I am very new to Rhino and this is my first time drawing curves on a 3D mesh in Rhino. I have a 3D mesh model, 2D transportation road, and 2D river in different layers.

  1. My question is how can I project those 2D lines to the 3D mesh model? (I had tried the “project” command but it doesn’t work.)

  2. Are there any ways to draw those curves (road and river) on the 3D mesh easily? or maybe do it in Grasshopper?

Best regards,

Hi HC - you can extrude the curves, extract the display mesh, and then intersect the meshes to get the curves on the terrain.

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Hello - if you are new to Rhino, just note that the default Project direction is normal/perpendicular to the current CPlane - so you need to be working in a view where the projection direction makes sense, or it will fail.


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Hi @wim,

That is a good idea. Are there any commands that I can pin the 2D overlay to a certain point, so as to map the road and river more accurately?

In addition, there will be some deformations after I extrude the 2D curve to the 3D mesh model, right?


Got it. Thanks Pascal!

Hi HC -
I’ve been doing that too many times in Grasshopper, it seems. There is no “project curve to mesh” in standard Grasshopper. In Rhino, as Pascal said, you can simply project the curve onto the mesh.

You’ll find that either the 2D curve or the 3D mesh is not “accurate”. Most likely both. There is no easy way around that. There are many plug-ins that will ease the construction of roads on terrain meshes. You can probably find scripts on this forum or could take a look at a complete package such as Lands.

Thanks. I have already installed Lands Design but seems that if I am going to make the 2D roads and rivers on the specific point on it, it is hard to do it.

I have attached a file that contains a simple 3D terrain and 2D road, how can I make the 2D roads on the terrain?

-HCtest.3dm (73.0 KB)