Geotagging, or geocoding involves the linking of photos to the place they were taken through latitude, longitude and altitude. Photos can then be displayed on a map, and become searchable by precise location. It is a great idea for travel shots, but not an easy task for those of us without a GPS. This article shows how to manually geotag your photos for use in a wide range of applications using Google Maps or Google Earth to find the coordinates.

Article index:

1. What is Geotagging
2. Software Options
3. Using Geosetter
4. Resources

1. What is geotagging?

Geotagging and geocoding involve the linking of information to a place. It is very useful for photographs, pinpointing where they were taken through latitude, longitude and altitude, and even bearing. It is a relatively new concept, so there are competing methods and standards, some less compatible with others. In general, fort this article I will make the following distinction – geotagging refers to the use of keywords (“geo:lat=”) in the IPTC keyword or description fields either in the image or in external files or a database, while geocoding uses GPS fields in the EXIF header of the image. You can do one or the other, or even both.

There are a lot of cool uses for geolocated images, mainly on social network photosharing like Yahoo’s Flickr, ( and loc.alize.us), and Google’s Picasaweb (and Panoramio) and Locr. These applications will continue to grow and improve as GPS technology is being embedded into cameras and phones (with cameras). If you don’t have gps, you can still join the party. Keep in mind that manual coding is not as precise, and sometimes people complain that the manual uploaders are inaccurate and off subject at times. Here are some things to keep in mind:

• You need to code for where the picture was taken, not the subject matter. Otherwise on the map it will look like you were halfway up Mt Kilomanjaro, not 15 miles away.
• Using different sources for positioning versus displaying an image can cause discrepancies. If your image location is generated somewhere different from the map it is being displayed on, it is hard to tell which to blame if something looks wrong.
• Using place names to look up coordinates can be inaccurate too. I looked up the Salty Dawg Saloon in Homer, AK using a search in Google maps, and it gave me the wrong spot, by 700 feet or so.
• The same problems can occur if you use software to generate tags for you. Suddenly your picture says it is in a completely different city or suburb from where it was taken. This is most common in large metropolitan areas with clusters of cities. The lookup might think you were in Park Slope, but you know you were in Prospect Heights when you shot that brownstone.

Salty Dawg – per website
(Salty Dawg Saloon, Homer AK.
Longitude 151° 25′ 10″ W
Latitude 59° 36′ 9″ N )

Where to put the metadata: IPTC vs EXIF

A note of explanation is probably needed here regarding IPTC and EXIF metadata. Metadata is additional information about media, either attached or embedded. By standardizing the names and methods of working with metadata, developers and consumers benefit since they don’t have to worry about compatibility issues. Standardized file formats, like JPEG have succeeded for exactly the same reason.

IPTC is an acronym for International Press Telecommunications Council, which develops and maintains standards for exchanging news. Photographs are one of their concerns, and  since the 1970′s they have developed fields for describing news pictures. Many of these fields were eventually embedded into many graphic file formats: JPEG, TIFF and even RAW files have headers with IPTC metadata. IPTC metadata is centered around describing the media, who and where and what, and works well with tagging for web use.

EXIF stands for exchangeable image file format, and though not capitalized by JEITA, its originator, is capitalized by practically everyone else, including me. EXIF is a standardized way of storing digital camera information in JPEG and TIFF images. EXIF data includes the make and model of the camera, the white balance and exposure information, practically anything the camera manufacturer might want to include in the image.While ITPC metadata is more user friendly, EXIF was not designed to be modified after the file was created. (Warning:  both IPTC and EXIF data can be stripped from an image if you edit the photo using non-compliant software.)

So IPTC would seem to be the easier, if not better place to store location information, since most photo software can read and write IPTC. The problem is that while IPTC has location, city, county, country  fields, there is nothing specific to geographic coordinates. One work around has been to add the “geo:lat=” keyword or tag to the image. EXIF however has GPS fields ready for the data. This is great if your camera has built in GPS, but problematic if you want to add it in later. 

Finally: Photographic metadata is in a period of change, as all these standards evolve. XMP is a technology from Adobe Systems that is becoming accepted as the standard for embedding metadata. It offers a way to combine the different standards, yet retain their individual purposes. Both EXIF and IPTC  fields are included within the XMP framework. So while XMP will likely replace many of these older standards in time, the geocoding of GPS data into images will be through the EXIF tags, and location type metadata will be through IPTC fields. 

The bottom line is that geotagging into IPTC keyword fields is a work around, given the difficulties of accessing EXIF metadata fields. On the other hand, getting GPS type data where it was intended to go, into the EXIF fields, requires special tools. In an ideal world, software could do both, as needed. For right now, I feel that geocoding into EXIF fields, (preferably in the file itself) is my best option.

The Geotagging Project Described

I have a series of photos taken along a three month road trip to Alaska. During the trip, I noted in the comment field of key images where they were taken, with the plan to annotate the rest when I got home. A year passed before I started the task. Instead of just adding a keyword or comment, I wondered about using the location fields in the IPTC data of the file. That seemed the most appropriate place. It then occurred to me that using Google’s map products, I could generate the EXIF geo data too. The problem is that my software (Lightroom, Irfan View, Photoshop CS2, Nikon ViewNX, even BreezeSystems DownloaderPro) didn’t allow direct access to the EXIF GPS fields for geo data entry.

Most people seem to be linking their GPS log to their images, but I’m not so technologically advanced. No GPS means I need Google to generate the coordinates. I want to use some of the images to highlight the trip on a map, either on this site, or on Flickr. I like clicking on a map and seeing the images spring up. I am not planning on doing this a lot, but it will be in the same circumstances, after a trip, when I have another batch. That means I want free software. I also want to maximize the usability of the info, so no compatibility issues.

Sidebar: How accurately can you click?

You need to realize that manual geocoding is an estimate. Don’t get too hung up on placing the photo exactly, but make it accurate and useful. GoogleMaps generates coordinates out 6 decimal places. One second (00°00’01”) = 0.00028 decimal degrees, so 0.000001 decimal degree is 1/28 of a second. One latitudinal second is 30.8 meters, so Google gives position within 1.1 meter in latitude, and 1.1 to 0.5 meters longitude, since it varies by latitude. There is no way I can click that accurately, yet Google generated coordinates imply that I can. I am looking for a way to tell people that my images are approximately located, so they don’t get all irritated. If you have a solution to this one drop us a line. (One suggestion is to use manual_geocode as a keyword/tag for the file)