Where was that taken?

Adding position information to digital photos (geotagging)

Given a typical amateur photograph or holiday snap, there are three common questions:
  1. What is that supposed to be ?
  2. When was it taken ?
  3. Where was it taken ?
With digital cameras, Q2 is solved. The time is encoded into EXIF data in the JPEG file (assuming that you have set up the camera's clock, have not got confused over timezones, and have not lost the data by image processing).

Q1 may be solved by audio titling - built into later Kodak cameras, I hear. Or one could use a timestamping digital voice recorder to keep notes and correlate the times as below; voice recognition software will give a text version.

We can solve Q3 using a GPS. The JPEG2000 standard actually allows position data to be embedded directly in the image file, and future cameras may have GPS built in, but for now we can add it later based on the timestamp.

The concept is fairly simple - the GPS saves its position continuously in a track file, which can be later downloaded to a computer. If a photograph was taken within a few minutes of a trackpoint, then the trackpoint documents where it was taken.

Here are some scripts used to make the photo index below:

The scripts use a Btree database for position lookup - a structure which lets the program quickly seek to records between two values, in this case the times of successive trackpoints.

Andrew Daviel

Photo Index

Index generated Tue Aug 22 10:39:08 2006 - This window may be resized as desired

Hold mouse over thumbnail for date/size; click for fullsize (opens in second window).


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In Berkeley Sound (Pacific Rim National Park)
Map
Photo
Snake on Helby Island
Map
Photo
On Howe Sound Crest Trail
Map
Photo
View of the Lions
Map
Photo
Mount Baker over Point Roberts
Map
Photo
Sail Training Ship "Concordia" docked at Steveston
Map
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Concordia'x figurehead
Map