Google Earth and Civil 3D

Google Earth and Civil 3D
James Coppinger

Importing aerial imagery into Civil 3D helps a design team use these photographic assets as the basis of their concept and preliminary designs. Autodesk — the company behind Civil 3D — and Google developed a simple tool inside of Civil 3D that allows you to import Google Earth images directly into your plans.

Locating imagery to use for the background and knowing how to bring it in at the correct scale and coordinate locations can be a struggle. There are a lot of software packages in the market that handle this functionality, including ArcGIS, Autodesk Map, and Raster Design. These programs require some training and a bit of effort on the part of the drafter to get them to do what you need. The Civil 3D partnership with Google Earth significantly streamlines this process.

Importing Google Earth Images in Civil 3D

The Google Earth images are not cheap screen captures, they are the full-blown aerial imagery Google Earth is noted for. Not only that, but when you import these images, they come in at actual size and in the correct coordinate locations.

The only drawback to the process is that you are limited to importing the Google Earth data as greyscale images instead of color. Nevertheless, these images are a fantastic tool for general construction documents, which are almost always released as black-and-white prints anyway.

Using Google Earth to Generate a Surface

Many professional engineering firms spend a fortune generating an existing surface (TIN) on which they base their proposed design. It's not unusual for these companies to pay top dollar for aerial topography firms to generate preliminary surfaces, spend time piecing together rough surfaces from older plans and other drawings, and dozens of other more arcane methods for getting a starting surface put together.

Google Earth offers a fully developed 3D surface of an area. It’s not the most refined surface in the world, but for a preliminary design, it will work just fine. The Google Earth surfaces are only accurate to within roughly 10 feet—certainly not enough for a real design, but if you’re just looking to get the general slopes on your site, or do some rough cut-and-fill calculations, this level of precision will often suffice.

Importing Google Earth Data

First, run Google Earth and zoom into the targeted area. The data you will import into AutoCAD is exactly what is shown in the Google Earth window. Next, open an AutoCAD drawing and make sure you set any map zones or coordinate systems you want to use. Now, just go to the Insert tab on your ribbon bar and click on the Google Earth option. In the drop-down menu that appears, choose the option that works for you:

  • Google Earth Image: Inserts a greyscale image at the correct size and coordinate location into your drawing.
  • Google Earth Surface: Inserts a fully built C3D Surface of the area you have displayed in Google Earth into your drawing.
  • Google Earth Image and Surface: Inserts both of the above, in effect giving you a nearly complete existing site plan in moments.
  • Google Earth Mesh: Creates a 3D Mesh, with real elevations at each vertex point, at the correct coordinate locations for your site.