Sparked by Editor B’s remarking upon my Google Maps and Indiana post of yestereve, a denizen of the Hoosier state drops a line:

It is interesting how the term “satellite imagery” is thrown around fairly casually these days. Google would lead us to believe that all their imagery is satellite imagery. In fact, the Indiana images are part of a statewide aerial photography project that was undertaken by the U.S. Department of Agriculture in 2003. Indiana looks different at small scales because this aerial photography is much different data than the majority of the course-scale satellite imagery displayed on Google Maps. Note the difference in resolution and color when you look close at an area near the state line.

The Illinois image probably has a 30-meter spatial resolution (each pixel is 30m x 30m), whereas the Indiana imagery has a 1-meter spatial resolution. This has a huge impact on the ability to view detail at large scale and the overall color of the image at small scale.

Note also that some areas of Indiana and other states have some areas of even higher resolution imagery.

I suspect much of this higher-resolution data is aerial photography–not that it matters much to the casual user.

You can view the same imagery for Indiana which runs on IU’s Research Database Complex.

Simply zoom in near Bloomington and turn on the 2003 Aerials (also need to turn off the 1998-1999 aerials).

Hope this clears things up a little.

The correspondent has been invited to provide self-attribution in the comments; if he does not, it’s due to privacy concerns.

2 thoughts on “U2s over Indy

  1. If you get the chance to check out Google Earth, try zooming in on Cambridge, MA. The imagery–which is different than the Cambridge imagery used for–is very high resolution, probably under one foot per pixel.

  2. For a look at a very good example of how this is very badly done, zoom in to Oahu, Hawaii. There is a total mix of really low-res color, very high-res b/w, and then some spots with absolutely no coverage, all on an area smaller than most mall parking lots. (Okay, not really. But still, why not shoot one single good map?) And you’d think some of this would have to do with military bases, but those have good coverage, while areas like North Shore’s beaches simply don’t.

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