Geo-referenced photography

The simplest way to link a photograph to a location is to combine two time-stamps: one from the digital camera, one from the GPS receiver. Given both sets of timestamps over the same period, a series of images and tracklogs can be processed to stamp each image with location metadata.

Compiled in July 2004 at the Hofn workshop in Iceland, during the work that became Time that land forgot. A working reference list of papers, projects, guidelines, tools and the technical issues that surrounded geo-referenced photography at that moment. Most of the links below are now dead; the list is preserved as a snapshot of what the state of the art looked like in 2004.

Papers

Prior work

Geo-referencing Photos

Commercial applications and scripts that link photographs to geographic information:

GPS track and waypoint extraction

Transferring data from GPS devices is awkward. For this to work in a wider collaborative context there need to be guidelines. It’s also important to make sure units and timezones are correctly set up on all software, so no translation happens as the data is converted. Exported data also tends to be messy, mixed tracklogs and waypoints, which for us meant a lot of hand-tweaking.

Extracting EXIF data

To get at the photographic data we need the embedded EXIF information: capture date, time, exposure, aperture.

Content metadata guidelines

To standardise the sharing of geographic information (tracklogs and waypoints) the format matters. We initially intended to use Locative Packets but have ended up with GPX alongside some custom XML for time and photo information.