Earlier this week when creating the map of Chinese map offsets it reminded us of a project we have long wanted to work on – mapping the density of historical imagery in Google Earth.
When you are in historical imagery and you look at the timeline, you can tell roughly how many historical images there are for the region you are viewing by the number of light blue bands on the timeline.
This location (Rio de Janeiro, Brazil) has a lot of historical imagery.
This location in rural Brazil, has very little historical imagery.
The only way we know of for automating the counting process is with the Google Earth API, and with the deadline for its end of life coming up this December we had better make use of it while we still can.
It will take a while to get the whole world done and decide on the best way to collect the data and the best format to show the results in, but we thought we would share some of our preliminary findings.
We have created a historical imagery density map for Spain and Portugal as seen below.
Strangely, over the oceans Google Earth sometimes reports no historical imagery but in other locations reports unusually high numbers. We are not entirely sure why this is, but it appears to be a bug in the way Google Earth reports historical imagery on the timeline. You can download the above KML file here
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We discovered that Google Fusion Tables has a remarkably easy way to create a heat map from a suitable KML file, as seen above. However the problem with high figures over the oceans drowns out the differences over the land. Nevertheless, there is a clearly more imagery over centres of population.
About Timothy Whitehead
Timothy has been using Google Earth since 2004 when it was still called Keyhole before it was renamed Google Earth in 2005 and has been a huge fan ever since. He is a programmer working for Red Wing Aerobatx and lives in Cape Town, South Africa.
google should care about the recent updates!
For example on Terraserver we can find a lot of images made on August 11th 2015 from the Kola peninsula offering great views of brand new russian submarines at Gadschievo 69.262602° 33.318384° and Olenya Guba 69.215855° 33.379567° and Severodvinsk where they rolled out the world biggest submarine (175m BS-64) exactly at that day.
I am really saddened by the fact that this is going away in a few months. I hope there is a better version of this on the web, like the time lapse using the LandSat imagery we saw last year