Modeling Terrain and Other Rounded Shapes

Terrain is important to many SketchUp modelers: Your building needs ground to stand on, or maybe you're modeling the ground itself to create a landscape.

But wait. SketchUp's Sandbox tools - the tools you use to model terrain - can also create forms completely unrelated to terrain. How can terrain include all these other possibilities?

The secret is in the hidden geometry. When you're modeling terrain (or other shapes) with the Sandbox tools, you're technically sculpting a special type of geometry called a TIN, or triangulated irregular network. That's a fancy way of saying, "a group comprised of triangles." The following figure shows a flat TIN that hasn't been sculpted into anything yet.

In the next figure, you see an example of a TIN sculpted into hills and a watery valley. The Sandbox tools are traditionally used to create this type of terrain.

Reveal the hidden lines in this bust of Beethoven, and you can see it's also modeled from a TIN.

In the following sections, you find out how to start modeling TINs, where to find the Sandbox tools, and what it means to geolocate terrain. After you cover the basics, you also find pointers to how to start sculpting a TIN.

Getting started with TINs

To create a TIN, you can import contour lines from another program or import terrain from Google Earth via SketchUp's built-in tools. You can also transform contour lines that you draw yourself into a TIN, or draw a plain flat rectangular TIN like the one shown earlier in this article. To get started, see Importing Preexisting Terrain and Creating Terrain from Scratch.

Note: You can also use the Sandbox tools to sculpt a polygon mesh, but only if you import it into SketchUp from another program. Importing Preexisting Terrain introduces this topic and points you to additional help with importing.

After you have a TIN in SketchUp, learn how to toggle the TIN's visibility, sculpt and fine-tine its features, and place other items on its surface.

Enabling the Sandbox tools

You find the Sandbox tools on the Sandbox toolbar or by selecting Tools > Sandbox and selecting your tool of choice from the submenu. As you read through this article's subarticles, you find out how to use each tool for its respective task.

Introducing geolocated terrain

If you're modeling terrain, you can geolocate it, or embed geographical coordinates that place your terrain at a specific point on Earth. Geolocated models (or geomodels for short) offer a number of advantages:

  • Study the sunlight and shadows at different times of day and on different days of the year. Shadow studies can tell you things like whether adding a second story to a house will turn a sunny garden patch into a shady hosta bed. You can also see how the sunlight shines into an interior space at different times of day.
  • View your model in Google Earth. Google Earth comes in free and paid versions that you download to your computer, and it's full of aerial imagery and models. This means you can view your model on the site where you plan to build it, surrounded by the buildings and landscapes that are already there. If you're modeling something for clients, seeing a model in Google Earth is sure to impress them.

For details about shadow studies and viewing a model in Google Earth, see Communicating Your Designs. As you model your terrain, know that you can geolocate it by importing terrain from Google, as explained in Importing Preexisting Terrain. Also, Modeling Terrain for Google Earth offers tips and tricks that can improve your model's appearance in Google Earth.

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