SketchUp allows us to create terrain from contours from a few simple steps involving the Sandbox set of tools. Sandbox does not appear in the default setup, therefore go to the Window drop-down menu and choose Preferences, then Extensions and tick Sandbox tools, and hit OK. Or right-click on the top toolbar and choose Toolbars and Sandbox. If you have purchased the SketchUp Pro version, you may import a contour lines CAD file into SketchUp.
It's recommended to prepare the file first in a CAD program like Autocad before importing to SketchUp. We would move the contours to the correct elevation, so they become 3D contours. It's also a good idea to put different elements on various layers, for example, buildings on a blue layer, contours on a red layer, site details on a yellow layer, etc. These will also be imported into SketchUp.
Open SketchUp and go to the File menu and choose Import with a Type of DWG, which is Autocad's native file format. Select the appropriate file and click the Options button to select Millimetres and OK and Open. Now go to Window and Layers to see that the Autocad layers have been imported too.
If however you only have the free Make version of SketchUp, you can't import Autocad files. In this case you have to import them as a JPEG, TIFF or PSD image. And then trace over the drawings with the Line, Spline and Arc tools. We would then move them vertically in the blue axis with the Move tool and enter each of the elevation values.
If it's necessary to scale these contours up, it's best if you have a scale bar on your image in order to use the Tape Measure (T) to drag across and enter the correct size. Answer Yes to the query, whereupon the whole model will rescale accordingly.
Lastly, we create the terrain by first selecting the contour lines. These should be ungrouped; explode them if necessary. Now we go to the Sandbox tools to choose From Contours, which is the first button on the left. Usually after a few seconds the 3D terrain is created, but this could take a few minutes if the size and detail of your contour map is large. The resultant file size is usually just a few MB and quite manageable. However, very detailed models may be unwieldy and slow to work with. In these cases you may be required to make some detail adjustments to get a good balance of detail to file size.
Once the terrain has been created we can add vegetation and other textures. Or we could add a site map using the Materials panel as usual. Alternatively we can use Sandbox's Drape tool to imprint site details like roads and boundaries.
Tom Gillan has been training sketchup courses to corporate clients in Sydney for seven years. If you like to know more about sketchup, visit Design Workshop Sydney for more information.