A DRG is a scanned image of a U.S. Geological Survey (USGS) topographic map. The scanned image includes all map collar information. The image inside the map neatline is georeferenced to the surface of the Earth.DRG Fact Sheet 
Focal length is the distance from the middle of the camera lens to the focal plane (i.e. the film). As focal length increases, image distortion decreases. The focal length is precisely measured when the camera is calibrated. Knowledge of the focal length...
Simply defined, scale can be expressed as the ratio or proportion between a distance on the aerial photographs (or maps) and the actual distance on the ground or land surface. It is a ratio that could represent any unit of measurement and this ratio is...
Remote sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance from the targeted area. Special cameras collect remotely sensed images of the Earth, which...
The majority of USGS aircraft photography is used for cartographic purposes. Image distortion is minimized when photographs are acquired looking straight down or vertically.Learn more:National Aerial Photography ProgramNational High Altitude Photography...
Yes.  Scanning of the EROS film archives is following a plan to capture images from rolls at risk of decay from vinegar syndrome. Science requirements are also reviewed on a regular basis, but a formal, on-line schedule is not available at this time....
The high resolution orthophoto and the Digital Orthophoto Quadrangle (DOQ) provides the most detail. You would probably be able to identify your neighborhood. There is no guarantee that your home would be distinguishable.What you can distinguish is...
Once you've gathered as many facts about family history and customs as possible, turn to maps to uncover more specific information or to solve historical mysteries.Old and new maps can help you track down facts about a branch of your family. How? In the...
The Photographic Library, located in Denver, Colorado, is an archive of still photographs dating from the 1870’s and taken by USGS scientists as part of their field studies. The works of pioneer photographers W.H. Jackson, T.H. O’Sullivan, Carleton...
The USGS has placed online a number of images taken by some of the photographers who worked for or otherwise accompanied the "Great Surveys of the American West."Before the USGS was established by Congress as a part of the Department of Interior, four...