Pixiq

Everyone is familiar with the GPS devices used for navigation in boats and vehicles, but this technology has other useful applications as well. Imagine returning from a trip through Europe or Asia with hundreds or thousands of digital images. Wouldn't it be great to be able to instantly identify the location where every photo was taken and then display the images on a map? That's certainly possible if you use a camera with a built-in GPS receiver or an external GPS device intended specifically for that purpose.

Either type can record data as to the exact latitude/longitude for each of your photos for later recall with imaging software or with an app such as Picasaweb or Google Maps. In other words, you can use the information to find map references to places where you took the shots even after you can barely remember the trip. 

How It Works

Whether it's intended for navigation or for storing location data, a Global Positioning System acquires data from satellites orbiting the earth. Maintained by the US government and available free to anyone, the 24 Standard Positioning Service satellites broadcast radio signals from space. A GPS receiver calculates its position by precisely timing the signals from at least three of the sources. It then  uses triangulation to calculate your exact coordinates, and even the altitude when signals from four satellites are available.

Digital cameras already record shooting data (aperture, ISO, shutter speed, etc) for each photo and GPS simply adds the specifics -- called geo-tagging -- about the location.  After you download the photos to a computer, you can view all of the information with imaging software by accessing the Properties or EXIF Data, also called metadata.  You can also view each photo on a map when using one of the applications discussed later.

In-Camera GPS: Several types of devices are available for attaching the geographic location data to images. The entire process is very simple when using a camera with built-in GPS receiver such as the three that I tested: the 10 megapixel Sony DSC-HX5V, the 12MP Lumix DMC-TZ10 (also called DMC-ZS7), and the the 12MP Samsung HZ35W.

Note re: Samsung: Samsung provided an SD card with maps for North America for my tests of the HZ35W but this is not included when you buy the camera. The user must download map files from Samsung's website and install them in the camera, a frustrating process according to many on-line comments.  

After successfully finding the necessary signals and completing the triangulation the entire process is fully automatic. It's just as straightforward with the optional Nikon GPS Unit GP-1 that I also tested although this accessory is external. It must first be connected to a D200, D90, D300s, D5000, D700 or a D3 series DSLR with a special cable (included) but then it acts just like an in-camera receiver does.

A new GPS device for Nikon DSLRs is available now from a company in Hong Kong http://www.solmeta.com/dede/index.html. The high-end unit ($250 US + $12 for a cable) sounds perfect, based on the specs. (One major benefit: both the high-end unit and the basic unit ($145 US + cable) include a built-in rechargeable battery so it does not consume the camera's battery ... until the built-in battery is depleted.)

However, I have not even seen the Solmeta product so cannot vouch for it. User reviews are provided at http://www.solmeta.com/dede/news.html but I'm not sure they are reliable. A better Review is available at http://www.geosolve.be/GeotaggerPro_EN.htm

Other GPS Devices: You can also use one of the aftermarket external GPS data loggers in brands such as ATP, Jobo, Gisteq, Igotu and Sony. This type is suitable for use with any digital camera (of any brand) that uses a certain memory card format, usually SD/SDHC. The GPS receiver does not attach to the camera so you simply carry it with you. I tried only one, the Sony Image Tracker GPS-CS3KA  in order to fully appreciate how an external device works.  

It operates in the same manner as the in-camera devices initially, finding and recording location data. However, the GPS-CS3KA (like other external devices) then requires an extra step to transfer the information from its internal memory to the image files' EXIF data folders. After shooting for some time, I inserted the SD/SDHC or Memory Stick Duo card from the camera into the Sony device. Pressing a couple of buttons caused the GPS-CS3KA to apply the geo-tag data to 60 images per batch, taking a couple of minutes.   

Note:The Samsung NX100, announced this week, will be compatible with a new GPS accessory. For additional specifics see my Preview report about this camera. Note too that the new Sony a55 digital SLR -- to be reviewed soon -- also includes a built-in GPS.

Mapping the Photos

Most of the built-in and external devices ship with software that allows for mapping the photo locations. Nikon and Sony provide the most sophisticated method with the programs they provide with the GP-1 (View NX) and the GPS-CS3KA (Image Tracker). Both programs will display a Google Map showing where you took each shot. There's no need to type in the location or geo coordinates since the application can instantly find that data.

Other applications that can read EXIF data—including social sites such as Flickr and Smugmug or software such as Lightroom 3, Aperture 3 and iPhoto—can also automatically map out your collection of images.

A friend with in-camera GPS recommended using Picasaweb, a free photo sharing site. Eventually I switched to this app for viewing and sharing all of my favorite geo-tagged images as a matter of convenience. After uploading them to a folder, I was able to view a small Google map for each image; my friends were also able to do so. Picasaweb also allows for automatically transferring a copy of the photos to Panoramio and/or to Google Earth . This allows for viewing thumbnails of every image on a larger map or satellite view display.

Note re: Privacy: Be aware of privacy concerns before posting photos taken near your home on sites with automatic GPS data importing. A few sites (such as Flickr) allow you to disable that feature but others may not.

Speed and Accuracy

The time required to acquire the satellite signals and to complete the triangulation varied from one device to the next. The Samsung HZ35W was a pre-production sample and produced a bit of frustration with 10+ minute start up times and a failure to find a signal one afternoon when the others all succeeded. Presumably the final HZ35W camera is more competitive with other brands. Of course, for most recreational use, reliability is far more important than the time required for full activation. 

The Nikon GP-1 was always the quickest; it was fully functional in an average of 45 seconds when used in a new area (cold start).  When turned off and back on later (hot start) -- in roughly the same geographic area -- it was ready to record data in 5 seconds. The Sony GPS-CS3KA device took several minutes for a "cold" start and under a minute for a "hot" start. Of the cameras with built-in GPS devices, the Lumix DMC-TZ10 was roughly as fast as the external Sony device and even quicker with a "hot" start. The Sony DSC-HX5V was just a bit slower.

None experienced any difficulty finding the signals or triangulating in areas with open sky. All of the units provided similar accuracy in terms of the exact position, such as the driveway of a friend's home. They always managed to get the location of the photos correct to within 10-20 yards. This should be adequate for most potential buyers.

GPS Tech Notes

Tech savvy readers may wish to know a bit more of the specifics as to how this entire process works. Here's all the essential information in a brief summary:            

• A GPS receiver can determine the location’s latitude and longitude by receiving signals from 3 or more satellites (geostationary satellite network)
• Data can be collected only when there is an unobstructed line of sight to the GPS satellites. Proper triangulation is not possible indoors and may fail (or be very slow) near tall buildings or whenever the unit cannot access at least 30% of the sky.
• The GPS satellites are controlled by the US government. The triangulating error allowed is about 30 yards but it's usually less. This depends on the position of the satellites, the atmospheric conditions, any objects blocking part of the signal, the receiver device in use and the accuracy of its clock.
• The time for triangulation varies greatly and depends on the unit. Initial triangulation in a new location (cold start) is the most time consuming taking one to ten minutes, depending on the receiver unit. Subsequent triangulation in the same area (hot start) usually takes only seconds  
• As the positions of GPS satellites vary constantly throughout the day, it may occasionally take longer than usual for the device to determine the location. Any tall buildings in the general vicinity (even if they don't seem very close) can also increase the time required to find a signal from three satellites.
• When the GPS receiver is on, a new reading is taken every 15 to 30 seconds, useful when you're on the move. A few GPS receivers -- such as the one in the Lumix DMC-TZ10 -- can continue triangulation even when the device is off, updating its position once every 15 minutes
• In-camera GPS and the Nikon GP-1 get power from the camera's battery, increasing consumption by about 30% with constant use. The totally external units hold their own batteries. With either type, it's important to carry spares.   

The Bottom Line

After geo-tagging images for several weeks, I'm definitely hooked on the concept and will take full advantage of it soon, when traveling in the U.S. Southwest. A camera with a built-in GPS is the most convenient but available with only a few cameras at this time (including the Samsung ST1000/CL65 and the Leica V-Lux 20, not tested). Hence, an accessory external GPS unit is particularly attractive. The two that I tested also provided faster signal acquisition, perhaps because of their larger internal antennas.

The Nikon GPS Unit would be ideal for owners of compatible DSLRs because of its simplicity of operation and pro-calibre styling. But the Sony Image Tracker is suitable for numerous other cameras (regardless of the brand). Granted, it's a bit more time consuming to use but also a lot more affordable. If you're a frequent traveler who shoots a lot of  photos that you plan to upload to photo sharing sites, you'll probably find geo-tagging to be real benefit. While location mapping may not be essential, it's definitely nice to have and it's a cool extra that your friends will appreciate while viewing your albums.