Worth Repeating.....

Frank Taylor, at Google Earth Blog, has an interesting discussion today on the sources of imagery in Google Earth (and, by extension, Google Maps and other ortho-viewing applications) . It bears repeating. Google Earth Blog is not officially connected to Google, but does a nice job of tracking and discussing issues related to Google Earth.

Today's post is actually points to very cool, very "near real-time," but very low-resolution imagery from NASA. But first it takes a detailed look at just how all that "satellite" data gets into Google Earth in the first place. Mr. Taylor explains the (lay-person's version) basics of satellite imaging, aerial photography, ortho-processing, and the complicated web of private- and public -sector partnerships that get the data from data creators and funders to sites like Google Earth.

Not all the imagery in Google Earth comes from satellites. A lot of the imagery comes from aerial photographers mostly in airplanes with special high resolution cameras. Some of the imagery even comes from kites and balloons. Google acquires imagery from a variety of providers. Some of the imagery is given to Google by city or state governments. The age of the imagery varies greatly, but most of the high resolution imagery is between 6 months and 5 years of age. Again, because the imagery comes from a variety of sources, the process to get this imagery into Google Earth is complex and involves a great deal of time and effort.

Thank you. We are all often surprised at how little the data users who interact with imagery via Google Earth, and Maps and their competitors actually know about where the data comes from. Any explanations that get out into the general conversation can only help.