Geotagged photograph

A geotagged photograph is a photograph which is associated with a geographical location by geotagging. Usually this is done by assigning at least a latitude and longitude to the image, and optionally altitude, compass bearing and other fields may also be included.

In theory, every part of a picture can be tied to a geographic location, but in the most typical application, only the position of the photographer is associated with the entire digital image. This has implications for search and retrieval. For example, photos of a mountain summit can be taken from different positions miles apart. To find all images of a particular summit in an image database, all photos taken within a reasonable distance must be considered. The point position of the photographer can in some cases include the bearing, the direction the camera was pointing, as well as the elevation and the DOP.

There are a few methods of geotagging photographs, either automatic or manual. Automatic methods provide the easiest and most precise method of geotagging an image, providing that a good signal has been acquired at the time of taking the photo.

Several manufacturers offer cameras with a built-in GPS receiver, but most cameras with this capability are camera phones as camera manufacturers after initial experience in the market came to treat GPS cameras as a niche market. The 2008 Nikon P6000, for example, an early geotagging camera, was replaced in 2010 by the P7000 which lacked that feature. Some models also include a compass to indicate the direction the camera was facing when the picture was taken.

The D1X and D1H that Nikon introduced in 2002 included a GPS interface. In 2006 the first special GPS receiver for Nikon was produced by Dawntech. Since 2009 Nikon has sold its own Geotagger GP-1. Canon uses the USB socket on the wireless file transmitter unit (WFT) as the GPS interface.

Some digital cameras and camera phones support an external GPS receiver connected by cable, or inserted into the memory card slot or flash shoe. The Samsung SH100 can connect using Wi-Fi to get position data from a GPS-enabled smartphone. Generally the relevant GPS data is automatically stored in the photo's Exif information when the photo is taken. A connected GPS will generally remain switched on continuously, requiring power, and will then have location information available immediately when the camera is switched on.

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Wikipedia