A geotagged photograph is a photograph which is associated with a geographic position by geotagging. Usually this is done by assigning at least a latitude and longitude to the image, and optionally elevation, 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 dilution of precision (DOP). Methods 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. Automatic using a built-in GPS 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. Canon EOS 6D Canon PowerShot SX280HS Canon PowerShot S100 Fujifilm FinePix F550EXR Fujifilm FinePix F770EXR Nikon COOLPIX P330 Nikon COOLPIX P6000 Panasonic Lumix DMC-TZ10 Panasonic Lumix DMC-TZ40 Sony Alpha 55V (DSLR) Some mobile phones with assisted GPS use the cell phone network to speed GPS acquisition times. Automatic using a connected GPS 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