Geocoding: Know Where You Took That Photo

By Author: Pierre Bernard
Total Articles: 1
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Faced with ever growing digital photo libraries, we struggle for ways of keeping it organized. The EXIF timestamp was first to help us at the task. Much like a neatly organized shoebox of photo prints, our digital libraries were sorted by dates. The fact that digital photographs are produced in much bigger quantities than traditional photographs soon showed the limitations of traditional organization. When have you last paused before pressing the shutter button? Thought of the cost of film, processing, ... ? Digital photographers shoot away. Triage comes later and often never.

Photo management applications like iPhoto, Aperture and Lightroom came in to help. They brought new concepts to the table: projects, tags, events, faces... Yet we hardly ever find or take time to wade through our photo collections to assign tags, name people in pictures,...

Apple was early to recognize the importance of geotags. Preview.app recognizes geotags and displays a map of the photo location. iPhoto'09 introduced Places: now photos may be browsed by location. iPhoto thus provides a very complete solution for exploring one's photo ...
... collection: by date, by tags, by events, by faces and by places.

Geotags do not only serve searching purposes. They answer crucial questions about our pictures: where was the photo taken, what is it showing, ... They may even give you the position of the photographer with respect to the subject. Now you may know if you are looking at the north or east side of the Eiffel Tower. Such information is not only of interest to the tourist or hobby photographer. It comes in handy when surveying construction sites, tracking animals, documenting deforestation,...

But how do geotags get attached to digital photos. Sure, we may tag them manually: for each photo locate a place on the map. But then, geotags are no different than regular keywords. We will soon find ourselves to busy (or lazy) to pursue this task.

Today only a handful of cameras are able to automatically geotag images. Unfortunately, those are expensive. They have long startup times and short battery life. A welcome exception are the camera phones, like the iPhone. Thanks to cellular tower triangulation, they are able to shorten GPS startup times. Each and every photo coming out of an iPhone is geotagged with no extra effort from the user.

Luckily for the casual user, there are easy to use and affordable solutions. Pure GPS track loggers come in keychain sized packages and often cost less than USD 100. Such track loggers record your position every couple of seconds. Thus building up a track log of where you have been. Battery and memory on these devices are usually able to create one-day-long logs. Carrying a track logger requires very little effort from the photographer. It is switched on in the morning and then attached to the camera bag. At the end of the day, it needs to be connected to the computer in order to extract the track log. Often times, this connection also takes care of charging the device.

At the same time, all digital cameras record timestamps for each photo taken. Software like HoudahGeo for the Mac is then able to match these timestamps to points on the track log. Thus the software figures out where the photographer was when the photo was taken. If a compass enabled track logger was used, HoudahGeo will also figure out the viewing direction. Thus giving even more precise information of what may be seen in the picture.

With HoudahGeo, casual photographers and seasoned professionals reach the same convenience they would get from using a GPS enabled camera. All without the drawbacks of reduced battery life and slow startup times. Most importantly though, this solution works for all digital cameras: your current camera as well as your future camera. The GPS gear remains separate from the camera. And it is affordable.

HoudahGeo is the one-stop photo geocoding solution for the Mac. It actually caters to two very different needs:

* Geotagging for archival purposes using EXIF, XMP and IPTC tags
* Geocoding for publishing to Google Earth, Flickr or locr

HoudahGeo connects directly to many brands and models of GPS track loggers. It also reads GPX, NMEA and TCX files created by third party software.