Projecting a road (open polysurface) on a mesh topography

Hello everyone, I’m new and hope finding help here. I’m new using rhino but i can handle it.

I’m creating a 3D of an area, and have already done the topography mesh, but now i’m searchnig for an efficace way to project the road on the mesh and then fusion to it to finally give the appearance of a road with its thikness. I’ve tried many way, the first was from CAD the polyline of the road are projected on the mesh and okay it marry the topography ut they are still line, si what i’ve done now is, back on planar plan of course and on CAD, I’ve made a region of those polyline road, extruded them, make intersection with another planar solid to give them the right thikness, but now on rhino I can’t project them on the mesh, the type of this object is an “open polysurface”, is there a way to project but for this type of object?
if there is a another simple way I’m open to it.

Thanks a lot for helping me.

kind regards


The problem is that a mesh is made up of discreet facets and projecting your road curves onto that will likely make very dense spiky polylines, and you will not be able to create a surface with them.

One possibility I can think of just off the top of my head if your mesh is sufficiently dense:

Create closed regions with your road curves (they do need to be closed!). Hide everything except the road curve(s) and your terrain mesh (or turn layers off). Select your mesh and turn on control points (F10). Type the command SelBoundary, set type option to Window, then select one of the road curves. That should select all the mesh vertices within the road boundary. Now, move the selected vertices a certain distance in world Z. Moving them up will make a raised “road”, moving them down will make a sunken “road”. If you have multiple road curves you will need to do this for each one.

This doesn’t actually create a separate road surface, it just makes a differential height in your mesh in the road area to create the appearance of a road… If your mesh is too coarse (not enough vertices), it will not work well…

There are some other possibilities as well, but perhaps more involved.


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Hi BoodMood - it’s hard to say without the file but a possibility is to MeshPatch the projected road curves and then OffsetMesh with the Solid setting checked, to give it some thickness.


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@Helvetosaur @pascal thank you so much, i’ll try it and then come back to you.

thanks a lot!