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The Nouveau Art of Geotagging

Text and Photos by David Langs

The Global Positioning System acronym, GPS, has been bandied about quite a bit over the past few years. The term and affiliated technologies are attached to more and more devices as each day passes, and the usefulness of a GPS tool, while sometimes obvious in certain arenas like in-car navigation, is not always so clear in the realm of photography. For example; the above photograph was captured digitally on October 4, 2007. I am easily able to ascertain this information as a result of what is contained within the metadata of the image file. This data was stamped at the time of exposure, and in some cases is sufficiently valid to be used as evidence in a court of law. The original Raw file retains the camera model and lens used, the set aperture, shutter speed, and exposure compensation applied to the photograph. Essentially, I have information to answer nearly all of the old "five Ws" (who, what, when, where, and why) save one. What I can't accurately determine is the "where." I have some basic information about it, but as my memory fades with time's passing, these remembered details will surely degrade. There are no landmarks or indicators in the image to assist me in determining its location. I threw some appropriate keywords onto the file during my cataloging procedure, so I do know I was in a town north of Budapest, Hungary on the date in question. The problem is: if required for the purposes of re-creation, journalistic accuracy or historical reference, I would not be able to produce the precise location where this image was taken. Thankfully, the problem outlined here has been completely eliminated since I began geotagging my photographs with GPS information.

GPS & Geotagging Defined

EXIF data is the information that is not embedded in a digital image but sits beside it and is contained within the JPEG or Raw file as a whole. You don't see this metadata while sorting files on your desktop, but when using a robust photo editing or viewing application, this data can be seen. There are a number of standardized fields in the EXIF template which your camera may not entirely fill out; one such field is for GPS-derived coordinates. Geotagging (or geocoding) consists of the act of applying latitude and longitude information in the form of coordinates to an image (optionally altitude, bearing, and nearby places-of-interest can also be stored). In the past, navigational equipment such as sextants with charts and a strong comprehension of celestial tracking were necessary to determine one's position upon this planet. Currently, as a courtesy of the US government, the 1972 NAVSTAR navigation satellite constellation - a series of American microwave broadcasters in medium earth orbit can be paired with the right equipment to allow the civilian population of any nation to easily and accurately pinpoint their location. All that is needed is a GPS receiver and a decent view of the sky - the level 4-G Pentagon clearance can be left at home…

At the heart of GPS units found in everything from cellphones to intercontinental ballistic missiles, lies a very basic chipset to receive the microwave satellite signals. A GPS chipset can calculate and determine a position using Pythagoras' old geometric theorem (a2 + b2 = c2 - didn't expect a math lesson in a photography article, did you? Just wait until we get into the inverse square law of lighting in the next one!) The receiver tallies the distance to each satellite in range by measuring the time it takes for the signal to arrive by using the formula: distance = speed * time. This arithmetic is at the root of those crusty old Algebra word problems where a train is headed to some big city at a set pace. The device will then output a set of latitude and longitude coordinates that take the form of degrees: minutes, seconds, or alternately as a decimal figure.

Identical coordinates displayed two ways via Google Maps

For the purposes of photography, (and to a degree videography,) the information gleaned from a coherent lock on GPS satellite transmitters can be applied by one of two methods. The first type, let's refer to it as "Active Tagging", makes use of a GPS receiver connected to or embedded in a camera. When activated, the GPS chipset simply transmits its current coordinates to the camera; then the camera embeds the data into the EXIF header at the time of exposure. This information is now a part of the image file, so as long as there is a clear signal whilst shooting, the ensuing photographs will all have their own geospatial data incorporated into the metadata.

The other method we will call "Multi-Stage Tagging." It involves a two-step process utilizing almost any handheld GPS receiver or an inexpensive device commonly called a GPS datalogger. This method requires the datalogger to be on and locked to the satellites for the duration of your shooting period. It then takes on the role of an electronic version of Hansel and Gretel's breadcrumbs, and saves a digital log of your path called a tracklog. So even if you are surrounded by hungry lions, tigers or bears, you won't have to be concerned about having your datalogged "breadcrumbs" being devoured by wildlife. A datalogger accomplishes this by constantly writing your current location to a single, simple log file in one of several common tracklog file formats. It will continually save your present location as long as there is a good signal and will save it at set intervals; typically one to five seconds between each reading. At the end of the day, vacation, or photo shoot, the second stage of this process begins. It generally requires that you upload the files to your computer, and then use a program to import the log file from the GPS datalogger. This application will match the date and time stamp on each photograph with the date and time stamp on the location file that is closest in time. Concerning JPEG photos, as the program appends each file, it does so without recompressing the image portion so there are no worries of image quality degradation.

The Requisite Toolset

The inherent benefits and hindrances of Active and Multi-Stage tagging are dictated by the types of photographic equipment used. At the time of this writing, Active tagging can be only accomplished by a small range of still cameras. Not all cameras have an input that can be translated and written to a file. A list of current and recent GPS-friendly cameras follows: To list the current and recent cameras that are GPS-friendly: Nikon D1X, D1H, D2H, D2Hs, D2X, D2Xs, D3, D200, D300, D700 and the Fujifilm S5 Pro and IS Pro. Using the Canon's wireless adapters WFT-E2/E2A or WFT-E3/E3A the Canon 40D, 1D III, or 1Ds III can accept data from a USB connected GPS receiver set to export data using the NMEA 0183 V2.01 protocol. In addition, the Hasselblad H3D-II features an GPS radio option as well. The Canon option for bridging GPS and digital SLRs will cost upwards of $1000 for the WFT transmitter and a handheld GPS unit with an USB line out. It is an expensive, but ultimately useful system, as the WFT transmitter add-on has a wide range of other desirable features.

Nikon MC-35 cord

Nikon on the other hand, has a 10-pin serial port on the front that not only is used as a remote shutter release input, but with select cameras it can also accept barcode info from a linked scanner, or more importantly, GPS data. Using the Nikon MC-35 cord, a GPS unit with serial output and transmitting the NMEA data protocol can be tethered.


Alternately, a tiny GPS receiver with a 10-pin lead out like the Custom Idea GeoPic II can draw a small electrical load from the camera batteries for its operating power. It nestles comfortably in the hotshoe, or if you have a flash attached, it can affix to most neckstraps. This unique receiver has three modes of functionality that allow it to conserve battery power in a low-power standby mode or lock a nearby location in order to geotag images indoors or where GPS reception is spotty. Any Nikon D2-series, D3-series, D200, D300, D700, Fujifilm S5 Pro, or IS Pro will play quite nicely with the GeoPic II. For those concerned with the loss of their remote socket, the GeoPic II has a 2.5mm remote socket for passing through signals to the camera. Ultimately, this means the ultimate sacrilege will be committed by Nikon users who will have to use Canon-type electronic shutter release cables. Of course, when comparing the price of Nikon remotes and Canon remotes, that awkward feeling will rapidly subside.


For those not wanting to fuss with cables or need to locate the GPS receiver further away from the camera, the Red Hen Systems, Blue2CAN Bluetooth module is indispensable. Using the Bluetooth wireless protocol, the Blue2CAN is a tiny adapter that fits unobtrusively into the Nikon 10-pin remote port found on the D2-series, D3, D200, D300, D700, Fuji S5.& IS Pro. It can communicate with Bluetooth GPS receivers or Bluetooth receivers/dataloggers such as the bundled Holux M-241 . This combination is certainly one to be strongly considered if minimalism and low pack weight are very important to you. Each Blue2CAN is bundled with IsWhere (Windows-only,) a software application that partners with Google Earth to verify and view on a map the location where geotagged images were photographed.

Looking into the other geocoding method, the Multi-Stage system is generally a less costly endeavor and entirely camera independent, as it needs only the right software and an inexpensive datalogger. Thusly, point-and-shoot cameras and digital SLRs alike can be used inconjunction with these location tracking devices. Accuracy is somewhat hampered by its nature of operation. If the datalogger records at one second intervals and you are hiking at a pace of two mph, the distance between readings is slight and therefore fairly accurate. If you are in a car traveling at 60mph, the physical distance between one second readings is much greater; Holux M-241therefore tracklogs can be less accurate.Dataloggers also require that they are active and operational for the duration of your shoot. This means you may have to carry extra batteries and stay outdoors where you have a clear path to the satellites. Furthermore, you have to keep an eye on your datalogger to make sure it is powered and saving data while you are shooting. The Bluetooth GPS receiver mentioned above, the Holux M-241, also functions as an independent datalogger with USB and Bluetooth connectivity. Following a journey, the M-241 will connect to a Mac, PC, or Linux based computer and appear as a removable drive on the desktop where the tracklog files can be copied and archived. Then the log file is to be imported along with the photographs with a geotagging application. Sony offers a tiny GPS datalogger in the form of the GPS-CS1KASP. It has some limitations if mounted on a non-Windows-based computer, but it is well-designed for all day use with a rugged design and a carabiner clip. The Sony datalogger is packaged with geotagging software that gives users the opportunity to see their image locations on a map.

Another low-cost option is the ATP GPS PhotoFinder, currently featuring a $10 rebate. It is a handy datalogger that can accept a memory card inserted into its built-in Secure Digital/ Memory Stick slot. Using this slot, this datalogger will non-destructively append JPEG EXIF metadata without the use of a computer. Its USB slot is bi-directional and can either connect to any computer as a removable drive or to a USB card reader to scan other card formats like CompactFlash or xD. This feature is really useful when you are traveling and may not have time or access to a computer to add the GPS data. Track files on a datalogger are time-based, but not time sensitive, so you can collect thousands of hours of tracking information into the PhotoFinder's 128MB of internal memory during an extended holiday and merge the EXIF data whenever you want.



Watch this Geospace

Geotagging can only be applied to images captured after one begins utilizing geospatial data, so there is no hope for my old image that I began this article with, but there is help for yours and my future photos. B&H now has a new and growing category of products on our website for Geotagging hardware and accessories . These products can be complemented with an array of software packages that are bundled with the GPS device or are widely available for free or with a minor cost. These programs can do everything from editing or applying coordinates into photo files to creating map-based web galleries. There are dozens if not hundreds of applications to be found on the web. Some of my personal favorites begin with Adobe Lightroom [tip: if you click the arrow to the right of the GPS coordinates in the Metadata tab in Library view, it will open your default web browser and bring you to the location in Google Maps.] Since I geotag my images at the time of exposure, Lightroom becomes a first-line organizing program for my images and their embedded EXIF info. When meshing data from dataloggers, a program like JetPhoto Studio is free, and has a low-cost upgrade for the pro version. Best of all, there are Mac and Windows versions of the applications, so nearly everyone is happy (sorry Linux users, try FreeFoote's GPS Photo Correlate). Breeze Systems Downloader Pro for Windows and HoudahGeo for OSX are the most popular geocoders for their respective platforms and are able to organize, export, and interface with or to Google Earth, Flickr and Panoramio.

Continuing on, this article will be followed by future discussions and further explorations of each of the geotagging products, the importance of this data, developing and incorporating GPS data into your workflow, improving reception and accuracy, and photo geocaching. I would also like to plug an upcoming seminar I will be delivering in the new B&H Event Space . The topic will be in regards to geocoding images, so if you are in the New York City area on September 4th, please feel free to drop by for a free class. Simply navigate towards 40.75463, -73.99782 and head to our new second floor and the Event Space classroom contained therein. Until then, the summer is still young and realistically you will be spending a great deal of time outdoors with your camera, so add a little "where" to your images – it helps when explaining "why."

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