After receiving feedback that children with autism really liked using SketchUp, the Google SketchUp team set up Project Spectrum . Project Spectrum also enlisted the help of the Boulder, Colorado chapter of the Autism Society of America, the Boulder Valley School District, and the Life Long Learning Lab at University of Colorado.
Google SketchUp was originally developed as a simple architectural visualization tool for 3D modeling. It's an easy to use 3D modeling tool that you can use to export files to Google Earth. You can download a free copy of SketchUp from sketchup.google.com. They also sell an upgraded pro version, but most people are fine with the free version.