Everyone else is blogging about the recent release of version 1.4 of NASA’s World Wind digital globe, so I might as well jump in as well. But I’ll do a listing of all the free available digital globes I’ve found.
Google Earth:Tops in terms of ease of use, user base, earth imagery, supported platforms (Win, Linux, Mac). Biggest disadvantage is that it’s not free for business or commercial use.
A worthy open-source alternative. Not as easy to use as Google Earth. Elevation database is superior, but baseline imagery isn’t as good. You can install a plug-in that allows you to use Microsoft’s Virtual Earth imagery, but that can only be used for non-commercial purposes. Other than that, it’s free for all uses, personal and commercial. Contains virtual globes for the Moon and Mars as well as Earth. USGS topo maps, digital orthoquads (1-meter black-and-white imagery), MODIS satellite data, Landsat data available in standard version. Supports KML and shapefiles. Extensive user community creating a wide variety of plug-ins to add additional capabilities. Currently Windows only, but a multi-platform Java version should be available later this year. Greater hardware requirements than Google Earth. Dapple is a specialized version for displaying geoscience data.
In addition to its original 2D view, Virtual Earth now has a 3D view. Has great 3D views of many cities, utilizing Microsoft’s extensive birds-eye view imagery. But only runs as a plug-in in Internet Explorer for now, and not as easy to use as Google Earth.
ESRI’s entry into the digital globe field. Lots of promise, especially as a vehicle for deploying data generated by other ESRI products, but not quite there yet. I can’t add much more to Stefan Geens excellent review. Not easy to find for download – try this link for directions (you’ll have to sign up for an ESRI Global Account). Windows only.
Descendent of TerraExplorer, one of the earliest 3D visualization tools. Works as a plug-in in Internet Explorer or Firefox; Windows only. Some interesting capabilities (built-in real-time GPS tracking, TrafficCam layer, custom weather, terrain tools, etc.); can plot shapefiles directly. Biggest weakness is the imagery, which appears to be mainly derived from USGS aerial photography. In cities like Tucson and San Francisco, with 0.25-meter color imagery, it looks great. Elsewhere, it looks like one-meter black-and-white digital orthoquads color-merged with Landsat imagery, which doesn’t look as good as Google Earth’s 2.4-meter color imagery.
My take: I use Google Earth as my main digital globe, since its ease of use and great imagery give it the edge. World Wind is a strong second, and I use it occasionally on my desktop; my laptop can’t handle it. Virtual Earth doesn’t have enough compelling content, or ease of use, to get me to use it that often. I’m keeping an eye on ArcGIS Explorer, but right now it’s not ready for prime time. SkyLine Globe loses major points for the quality of its imagery.