Natural Earth is a public domain map dataset available at 1:10m, 1:50m, and 1:110 million scales. Featuring tightly integrated vector and raster data, with Natural Earth you can make a variety of visually pleasing, well-crafted maps with cartography or GIS software.
M. Hampe, M. Sester, и L. Harrie. ISPRS Congrese, том XXXV из International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences, стр. 135-140. Lund University, Dept of Physical Geography and Ecosystem Science, (2004)