Creating terrain from contours is an easy process in SketchUp, utilizing a set of tools called Sandbox. This is just one of the many features we explore in our SketchUp courses.
First of all Sandbox may not appear in the default setup, so go to Window > Preferences > Extensions > tick Sandbox tools > OK. Alternatively, right-click on the top toolbar > Toolbars > Sandbox.
If you have bought the SketchUp Pro version, you can import Autocad files for your contour lines. A plug‐in was
available for the free version of SketchUp 7.1, but has not been available for the free version since.
It’s best to prepare the file first in Autocad by moving the contours to the correct height, so they are 3d contours, before importing to SketchUp. You’d also put different elements on various layers, eg. buildings on a red layer, contours on a yellow layer, site details on a green layer. These layers will be imported into SketchUp too. Then in SketchUp you go to: File > Import > Type: DWG > select the file > Options button > Millimetres > OK > Open. If you go to: Window > Layers – note that the Autocad layers have been imported too.
However you can’t import Autocad files into the free version of SketchUp, in which case you’d have to bring them in as a JPEG (or a TIFF or PSD) image. Then trace over them with the Line tool, and move them upwards in the blue axis into position with the Move tool.
If you need to scale the contours up: zoom into the scale bar on your image and use the Tape Measure to drag across the scale bar and punch in the correct size. The whole model will rescale accordingly.
Lastly, to create the terrain, select the first contour lines. They should be ungrouped – explode if necessary. Go to the Sandbox tools and choose From Contours (first button on the left) and the 3d terrain will be created. This could take a few minutes depending on the size and detail of your contour map. The file size is usually just a few Mb and quite a manageable model. Very detailed models can be unwieldy and slow to work with though. It may require some experimentation to get the right balance of detail versus file size.
You can now add vegetation or a site map via the Materials panel as usual. Drafted site details like roads and boundaries can also be added using Sandbox’s Drape tool.
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