Connecting digital photos to location data

A digital camera which embeds GPS coordinates in the photo is of great value, and will probably become widely available over the next few years. In the interim, there are some alternatives to either paying an excessive price or accepting low quality photos for the privilege of embedding gps coordinates in the file.

Once the digital camera and supplies are purchased, the photos are essentially free, so you can adopt a different philosophy concerning the use of a camera. One good and easy way to document field activities is to simply photograph a sign or diagnostic feature before you begin a series of photos. If you adopt a consistent system of naming photos, you can simply take a photo of a meaningful sign at the start and then if the photos are labled consistently, they will be filed in order and will therefore be linked to their location. Then when you rename the photos you can embed the location in each photograph file in several ways, discussed below.

If you have a gps unit you can write down the location on a peice of paper and photograph it (this allows you to add other information too), or just photograph the screen of the GPS unit before each photo or before each photo series. Then when you process the photos (i.e. when you give the digital files meaningful and consistent names) you have several options.
1. Read the gps coordinates from the photo of the gps screen and type them directly onto the following photograph. This has the benefit of being simple and clear to interpret, but does cover up part of the photograph and you may want an unaltered copy of the photo later. You could resave as a separate file to avoid this problem and keep both the new file and the original (photos are essentially free).

2. You could join the two photos together to make one photo so the location data is directly connected to the field photo. This may be acceptable if you only have a few photos to process, but is very cumbersome if there are many photos.

3. A better method is to read the gps screen and enter the coordinates into the set of information that is stored within the digital data of the photograph. There are several ways to do this.
- Adobe Photoshop, an industry standard for processing digital photos, will allow you to enter data into "fileinfo". With the photo open in photoshop, select the "file" menu and choose "fileinfo". A screen will appear like the following. You don't have to use the data they suggest. You might enter lat/long in the "caption" section. Or there are several other screens available to store information. Then just save the file normally and the data will be embedded.

Another program "ThumbsPlus" (http://www.cerious.com/thumbnails.shtml) allows direct access to another set of hidden information within the digital file. Right clicking on a photo file will offer a choice to "edit IPTC info". That will send you to a screen like this:
Once again you can enter the data in any of the categories--perhaps "caption again"

You could also just synchronize the clock in your camera with your GPS unit (your GPS is the most accurate clock you will ever own). The date and time of every photo (in addition to information conerning the photo itself) is automatically stored in each file, within one second intervals. If you take a GPS point right before you shoot each photo, you can later match each photo to the gps location by matching the dates.

If you store GPS points for each photo point you can then easily overlay those points on a map or air photo, label them with numbers or other identifiers, thus allowing you to add text referring to specific known points on the maps or air photos.

Of course all of this requires the discipline to process the photos very soon after they are taken, and to follow a consistent methodology.