Historic aerial photography (in some cases dating back to the 1930s) is often available from the Natural Resources Conservation Service (NRCS) regional/local office or the Farm Service Agency (FSA) office. Recently acquired aerial photography can often be obtained from your local government (city/county government) office. Contact the local government GIS coordinator. Most cities and larger towns have someone responsible for GIS. If not, then often the planning department, assessor’s office, or engineering department is a good place to get started.
Many states have initiated a state-financed digital orthophotography program. In some states, these data are available for free through a state GIS clearinghouse (i.e., the Georgia GIS clearinghouse). Other states may not have a GIS clearinghouse but may provide these data to users on request. Some states (i.e., Virginia) have instituted a cost recovery program and may charge for digital imagery. To determine the status of state-conducted imagery programs, contact your state GIS coordinator. This information can be accessed through the National States Geographic Information Council (NSGIC)
There are several federal/national data clearinghouses where you can also access aerial photography. The USDA, through the Aerial Photography Field Office (APFO), provides access to aerial photography acquired through the National Agricultural Inventory Program (NAIP). These data can be streamed to your GIS application through an ArcIMS data service called the NAIP Data Viewer
, or it can be downloaded (MrSid format) from the NRCS Geospatial Data Gateway
. Most of this imagery is available for rural areas (sometimes urban areas are not available). In addition, the United States Geological Survey (USGS) National Map
and the USGS EROS Data Center
have aerial photography available for download. Try the Geospatial One Stop
for these and a number of other options.
If you need an image primarily for spatially referenced visualization without analysis (e.g., placing an aerial photo in a report), the USGS and Microsoft and other partners have created an online mapping service called TerraServer-USA
where you can obtain JPEGs of USGS aerial photos and scanned topographic maps with a "world file" (an associated text file with the geographic coordinates of the image).
Satellite imagery can be obtained from both public and private sources. Public satellite imagery can be downloaded from an imagery clearinghouse in your state. A good place to start is your state GIS coordinator or GIS clearinghouse. In some states, you can try to contact an AmericaView State Coordinator
. In addition, the EROS Data Center
provides additional links to satellite imagery downloads.
Free imagery obtained from government or other sources also resides inside of many popular Internet applications. Many navigation services such as MapQuest and GoogleMaps have embedded imagery, as do very powerful imagery visualization applications like Google Earth, ESRI’s ArcGIS Explorer, Microsoft’s Virtual Earth, and NASA World Wind. Some of it is aerial, and some of it is satellite. You can print and use these services without having to store the data, and some are even providing you the capacity to load your own images and GIS data so that you can work with and share your data online in relationship to much larger imagery data sets.
A number of private sector companies can also provide you with aerial photography and/or satellite imagery.