How to Smoove Existing Terrain in Google SketchUp 8
No matter how you’ve made the terrain model you want to edit in Google SketchUp, it probably consists of lots and lots of triangles. Switch on Hidden Geometry (choose View, Hidden Geometry) to see them. As long as you have triangles, you can use the Google SketchUp Sandbox’s terrain editing tools.
Keep in mind that both From Contours and From Scratch create terrain objects that are groups. To edit a group, double-click it with the Select tool. When you’re done, click somewhere else in your modeling window.
Smoove is a tool for moving smoothly, and it’s actually one of the coolest tools in SketchUp; it lets you shape terrain (or any horizontal surface that’s made up of smaller, triangular faces) by pushing and pulling (sort of) bumps and depressions of any size. Smoove is fun to use and yields results that you’d be hard-pressed to produce with any other tool in SketchUp.
Follow these steps to shape a surface with Smoove:
Double-click the group containing your terrain to edit it.
Choose Tools, Sandbox, Smoove from the menu bar to activate the Smoove tool.
Type a radius and press Enter.
Smoove creates lumps, bumps, and dimples that are circular. The radius you enter here determines how big those lumps, bumps, and dimples should be.
Click somewhere on your terrain surface to start smooving.
Move your mouse up or down (to create a bump or a depression, respectively), and then click again to stop smooving.