Coupled with information about the field of view of the lens and focus distance, it’s theoretically possible to capture lots of information about the exact position of what’s in the photo, not just where the camera happens to be.įIgure 3 Here’s what GPS data looks like inside a GPX file. For instance, some devices now include compasses and inclinometers.
The Metadata Working Group is reviewing this schema and may come out with some new specifications before too long. It includes latitude, longitude, altitude, timestamp, and a bunch of other stuff that’s relevant to a larger travel record (not the location of this particular photo). Metadata embedded in the EXIF needs to be in GPS Exchange Format (GPX), an open standard XML schema for recording position and direction information, as shown in Figure 3. GPS data can be stored in a number of formats, such as those created by Garmin, Magellan, or Google’s KML. For instance, it will be possible to automatically tag photos shot at the time and place of the Super Bowl with the keyword “Super Bowl.” In the near future, GPS data, along with a timestamp, will enable some good guessing about the nature and subject matter of the pictures. Moreover, some databases can translate the GPS coordinates to location place names automatically, saving you the trouble of writing location names into your bulk metadata. With accurate map coordinates and a timestamp, you’ll never have to doubt where a photo was made. Place names change: countries rise and fall, people buy and sell property, earth is turned to street, and buildings are built and torn down. Not only does GPS data enable more precision, it can stand the test of time. This is the kind of place that can't easily be described with traditional location notation, but can easily be pinpointed with GPS. The IPTC fields may only be able to say, for example, that you took a photo in the Tasmanian State Forest, Tasmania, Australia, but GPS data can pinpoint a location of –41° 13’ 58.10”, +147° 59’ 12.26”, which is a precise spot within the state forest (Figure 1).įigure 1 shows an image in Expression Media, along with a screenshot tagging that image on Google Maps.
Unlike the IPTC location fields, which provide incomplete and sometimes subjective information about where a photo was shot, GPS data can provide an objectively precise position. While the process is generally hard to fully automate, it's getting much easier. And there are dozens of freestanding applications that can add GPS data to image files. Popular image management software, such as Adobe Lightroom and Apple's Aperture offer GPS integration is various forms. DSLR cameras frequently offering the ability to add a GPS tagging module either from the camera manufacturer or a third party. Some digital cameras now have GPS receivers, but these tend to be point and shoot cameras.
The direction information, for instance, refers to the direction of travel, not the direction the camera is pointed.) (Although there is a lot of other information that can be saved in GPS metadata, it’s harder to mash-up most of it usefully with the photo. This information can be used to determine the precise location of the camera when a photo was taken. Since we’re mostly concerned with information about the instant the shutter was snapped, we’ll mostly be interested in the latitude and longitude data and sometimes the altitude. GPS data can include latitude and longitude, as well as altitude, speed, direction, and more.
#Gpsphotolinker series#
A GPS receiver uses a series of geostationary orbiting satellites to compute its location by triangulation. GPS technology was first developed for the US military for use in determining precise locations.
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