According to wikipwdia, Geotagging is the process of adding geographical identification metadata to various media such as photographs, video, websites, or RSS feeds and is a form of geospatial metadata. This data usually consists of latitude and longitude coordinates, though it can also include altitude, bearing, accuracy data, and place names.

Regarding photos, we are basically talking about adding coordinates (latitude and longitude) to the metadata of the images, so you can track back the location where the picture as taken.

Many uses can arise from this information. For me, being able to pinpoint my memories or being able to go back to a certain interesting theme are the main ones. Of course, when you start making money out of photography, being able to setup a shooting location from your past work is also an important feature…

OK, so by now it should be clear that Geotag is geographic metadata added to each photo. The probable next questions are: How do I do it? What do I need for that?

Lets take one question at a time.

How do I do it?

There are several approaches for this. Some require user intervention and some don’t. Its all on the equipment you already have and how much you are willing to spend. In my case (as I’m trying to get the D300 I’m willing to spend as little as possible on this, but I’ll get to it in the third part of this topic). So lets go through the most common ways:

Your machine includes a GPS

Well, this is the simplest way. Your pictures are already being geotagged. Try looking at its properties. If you can’t find the information, take a look at the camera’s manual to check if there is some setup left to be done.

I have a photo specific GPS

Usually these units already have a process that allows the GPS information to be written to the EXIF data of your photos. Some are connected to your camera through a cable. Others connect through BlueToth and last but not least, there are those that require post processing through a software that link the pictures with the GPS tracking data. How is this achieved? Well, to start with, you have to synchronize the camera’s clock with the GPS. Te GPS stores tracking information (a collection of pinpoints with time-line) and in post processing, the software looks at the time a picture was taken and matches the location from the tracking data at that precise time. Quite simple and lovely decoupled process, wouldn’t you say??

There are still some units that have a card reader/writter and into which you insert your card with the photos. The unit will edit the photos adding the geographical data. An example of these units can be found here.

Examples of disconnected GPS units:

 Sony GPS tracker for photographers

ATP GPS Photo Finder

I have a GPS and a a camera that don’t fit together in any way (that’s my case)

Well, this is basically similar to the previous case, where a post processing is required to do the trick. You just have to check:

1. that your GPS cant keep record of your track and how large that track can be (check the references)
2. that you can extract that track from the GPS

From then on, you just have to use a geotaggingsoftware (if you want to automate the process) or some EXIF editing software if you want to do it by hand.

I don’t have a GPS, can I geotag?

The answer is: certainly!

There are a couple of tools available, mainly related to the freely available map engines (Microsoft Virtual Earthanf Google Earth).

For MS Virtual Earth, you can use the free Microsoft Pro Photo Tools (I describe them in this post).

For Google Earth, you can use Flickr or Picasa.

On the next post (Geotag: The tools and the equipments)  I will try to focus on tool details and current available selection. Stay tuned.

This post is part of a series of posts regarding the full Geotag Scenario. You can find the index on the top post: Geotag.