My Google Map Blog

We have previously had a look at how to get Landsat imagery into Google Earth. We have used a number of different techniques over time, but in all cases, obtaining high quality Landsat imagery required a large download (typically over 700 Mb) and several stages of image processing to combine multiple bands into a full colour image.

We recently discovered Snapsat, a website dedicated to making it easier to obtain processed Landsat imagery. In March last year, Amazon announced the availability of Landsat data on Amazon Web Services (AWS). Snapsat builds on the AWS, offering to provide easy access and processing of the Landsat data. It appears to have been set up mid last year not long after the Landsat data was made available on AWS but not much work appears to have been done on it since then. However, it still works well and makes obtaining processed Landsat imagery remarkably easy. Learn how to use it here.

As we mentioned in this post there was a Tornado which struck Dallas, Texas in December last year. There is no imagery yet in Google Earth showing the main path of destruction. So we tried out Snapsat by downloading a Landsat image of Dallas from January 12th. The process was straight forward and only required a download of 107 Mb as opposed to the 772 Mb required to download the same imagery from Earth Explorer. And we can see the track of the tornado.

Tornado track, Dallas, Texas, as seen in Landsat imagery. Ends of the track marked with arrows.

There are, however, a few disadvantages to using Snapsat. The website does not do pansharpening, a process whereby a higher resolution grey-scale image is used in combination with the three colour bands to create a higher resolution image overall. This means that the imagery obtained via Snapsat is not the highest quality possible. Another issue is that the downloaded file does not include Geo-coding information so it cannot be automatically imported into Google Earth Pro. However, since we usually have to crop the imagery anyway, manual positioning is often necessary and not very difficult.

We got the same image from Earth Explorer and used GIMP to process the imagery (very inexpertly) and the result is noticeably sharper because of the pansharpening.

Tornado track, Dallas, Texas, as seen in Landsat imagery, with basic pansharpening via GIMP

To see the two overlays in Google Earth download this KML file.

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