Global Mapper is topographic 3D mapping software that not only is just a viewer capable of displaying the most popular raster, elevation and vector datasets, but converts, edits, prints, tracks GPS and allows you to utilize GIS functionality on your datasets in one low-cost and easy-to-use software package.
Global Mapper can also directly access online sources of imagery, topographic maps, and gridded terrain data.
Global Mapper gis mapping software includes access to worldwide high resolution color imagery from DigitalGlobe (watermarked access for free) and access to the entire TerraServer-USA database of USGS satellite imagery and topographic maps free-of-charge.