Digital Earth Weblog

The current hype over the imagery available in Google Maps/Earth is driven by the fact that it is high resolution, and less than a few years old. What might surprise users of the Google tools is that there comes a point in time where aerial and satellite imagery starts to increase in value as it gets older. It can be used to show the changes that have occurred over time.

A lot of old imagery is rotting in tape archives and storage rooms, but yesterday I had the rare privilege of working with some aerial photography of Sydney captured in 1943. Yep, forty three. A government agency had the original negatives in their archive. One person made it his mission to not let it disappear and had it all scanned.

Part of the series has now been orthorectified, mosaiced, and compressed into ECW format with a cell size of 0.2 metres. My minor task was to add it to their Image Web Server website. Anyone in the organisation can now browse this imagery alongside the latest aerial photography. Very cool.