How to Create Paths and Roads in Google SketchUp 8
Perhaps you’ve created a gently sloping terrain in Google SketchUp and you want to draw a meandering path on it. The path has to follow the contours of the terrain, but because you want to paint it with a different material, it needs to be a separate face. In this case, you’d draw the path on a separate face and use the Drape tool to transfer it to your terrain surface.
The Drape tool works a little like a cookie cutter; use it to transfer edges from an object down onto another surface, which is directly beneath it.
Use the Line tool to draw a flat face somewhere directly above your terrain surface.
If you can, make your flat face exactly the same size as your terrain. Just make sure it’s big enough for whatever you plan to draw next (in this example, a path).
Paint the face you just created with a translucent material.
There’s a good light gray in the Translucent library, inside the Materials dialog box.
Use the Line tool to carry up any important points on your terrain surface.
In this case, make sure the path begins precisely at the door of the building, so draw vertical lines from the sides of the door to the flat face directly above. That way, you have something to inference to in Step 6.
Choose Camera, Standard Views, Top from the menu bar to switch to a top view.
Choose Camera, Parallel Projection from the menu bar to turn off perspective.
On the upper face, draw the edges you want to drape.
Make sure that your edges form closed loops to create faces. If they don’t, you’ll have a miserable time trying to paint the path (in this case) after it’s draped onto your terrain surface.
Orbit your model so you can see both the upper and lower surfaces.
Soften/smooth the edges of the triangles in your terrain surface (if they aren’t already).
Select all the edges and faces in your terrain, and then choose Window, Soften Edges from the menu bar.
In the Soften/Smooth Edges dialog box, move the slider to the far right and make sure that both the Smooth Normals and Soften Coplanar check boxes are selected.
Select the edges you want to drape.
If your edges define closed faces, you can select those faces instead; sometimes that’s easier than selecting a bunch of individual edges.
Choose Draw, Sandbox, Drape from the menu bar to activate the Drape tool.
Click once on your terrain surface to drape the edges you selected in Step 9.
It doesn’t matter if your terrain is inside a group; the Drape tool works anyway.