TerraExplorer is described as 'Powerful, easy to use tool to build, analyze, and navigate high resolution 3D world environments created by fusing aerial and satellite photography, terrain elevation data and other 2D and 3D information layers.onto a 3D map' and is an app. There are more than 10 alternatives to TerraExplorer for a variety of platforms, including Windows, Web-based, Mac, iPhone and Linux apps. The best TerraExplorer alternative is Google Earth. It's not free, so if you're looking for a free alternative, you could try Google Earth or Leaflet. Other great apps like TerraExplorer are NASA World Wind, Bing Maps, Bing Maps 3D and StarCalc.