GPS Photography AKA Geotagging:
Making Use of GPS Photography
GPS photography or "geotagging," is the practice of attaching GPS coordinates to digital photos. These coordinates can be obtained in one of two ways: a camera with a built-in GPS system, or a GPS receiver which is time-synched to the digital camera. Currently, very few digital cameras come with their own GPS systems. Most of what’s available are high-end models geared toward professional photographers, with a price tag to match. With these cameras, the location is automatically logged in the camera’s metadata; which is the auxiliary information such as aperture setting, time, date, etc. that is embedded in each photograph’s file. No other software or hardware is required.
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Cameras with built-in GPS systems are rare, but there are many types of external GPS receivers available. Sizes, functions and prices vary among these receivers depending on how the receiver logs the coordinates and how long the battery lasts. For example, one type of receiver records the user’s coordinates every 15 seconds and runs on one AA battery, which lasts about ten hours.
Another type of receiver attaches to the flash shoe on the camera, logs coordinates every time a photo is taken and records them on a built-in memory card. The important point to remember with these receivers is to synch the clock on the camera to the clock on the receiver. Also, since latitude and longitude are calculated in relation to Greenwich Mean Time (GMT), setting the camera’s clock to GMT will make matching locations with photos much easier.
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GPS photography (geotagging)
To match the photos with their locations, both the pictures and the GPS data are uploaded (usually via USB cable) to a computer. With specialized software (e.g. mapping software like Google Earth), the computer compares the time stamp of the photo to the time stamp from the data on the receiver to attach location information to each photograph. This process is called Geotagging (or Geocoding) and refers to adding geographical information such as latitude, longitude, altitude, and place names to various forms of media. Depending on the mapping software and the type of receiver, the photos can be labeled and organized according to their location.
All photographers, amateur and professional, can benefit from photos encoded with GPS data. Using the data, pictures can be easily organized and classified, especially photos from areas of special interest. Biologists can use GPS photography to monitor endangered plants and animals. With the location information tagged onto the photo, the scientists know exactly where to look and exactly what species to search for. Researchers looking for photographs of a certain area can simply enter the coordinates into a Geotagging-enabled image search, and researchers seeking certain news, or location-based websites can use the GPS data as well.
Though spectacular, the technology of GPS photography isn’t perfect. The GPS satellites transmit signals via line-of-sight, which means the receiver needs to “see” the sky in order to fix its location. The GPS signal is able to transmit through clouds, glass or plastic, but not through mountains or buildings. When taking photographs indoors or in deep valleys surrounded by mountains, the GPS receiver probably won’t get the satellite signal, so no GPS information can be attached to the photo.
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