Semi-Realtime Satellite Desktop Backgrounds
Posted on January 10th, 2010 by Russ. Filed under Space.
Snowy Great Britain
A few days ago, a beautiful satellite photo of snow-covered Great Britain got quite a lot of press coverage (and garnered me a couple of hundred retweets). The image was taken with the snappily-named MODIS camera which flies aboard two NASA Earth Observation System satellites: Terra and Aqua.
Turns out these are pretty neat pieces of kit — they actually record images in 36 frequency bands ranging from blue to thermal infra-red. The two satellites are in a sun-synchronous polar orbit which means they each record an image of the whole earth every day: Terra in the morning and Aqua in the afternoon.
All the image data is collated and released into the public domain by NASA on several sites, but the most interesting outlet for the data is the semi-realtime site here.
It struck me that it would be pretty cool to have the most recent image on your desktop, updated twice a day. So I wrote a slightly hacky little script to do it. NASA provide georectified true-colour images for a selection of regions, including most of Great Britain, so I’m just co-opting that. It does mean I don’t have a full image of GB, but my screens aren’t really the right aspect ratio for that anyway.
Here’s an example of the image it produces (for my dual 19″ monitor setup at home).
I’ve just learned that the MODIS satellites constantly downlink their imagery in the clear, so I think the next step is to build a receiver and grab the data directly ;).
January 10th, 2010 at 19:22
Do you fancy posting the script? :)
January 10th, 2010 at 22:00
Here is what I wrote:
http://pastebin.com/f74ecf3a
imagemagick is needed. Don’t know if it works yet ;)
January 11th, 2010 at 09:01
Heh, sorry guys. I embedded the code in my post using Github’s Gist embedding feature, but that’s obviously not working for some people (it requires Javascript), so I linked it too.
January 11th, 2010 at 09:56
A very quick mod to get it working on OSX. Set it to MBP resolution too, but don’t think I’ve got the positioning right – can’t tell as it’s too cloudy…
http://gist.github.com/274116
Again, just requires imagemagick – use homebrew.
January 12th, 2010 at 10:12
Oh right, I use NoScript so I didn’t see the javascript ;)
In the meantime I hacked up a bash script to run on a server somewhere to do the processing so my laptop can just download a correctly sized image whenever it’s ready, but it’s functionally identical to yours.
FWIW, the gconf thing isn’t strictly necessary, in that you can just overwrite the current desktop file and nautilus will notice and reload it, but if you want history then gconf is the way to go.
January 12th, 2010 at 15:08
Curious, auto-refreshing doesn’t work on my Ubuntu install at home.
It’s worth noting that those JPEG images on the server are actually generated on-demand by their site when you want to view them, so this isn’t an ideal realtime system.
January 13th, 2010 at 14:15
[...] The MODIS Rapid Response System provides publicly available daily satellite images of Earth which Russ Garrett has neatly used in a script for your desktop wallpaper. Daily satellite images bring up a slew of other ideas. Someday the “Google Earth lets [...]
January 13th, 2010 at 20:03
Maybe the auto-refreshing is a new feature, I’m running Lucid already.
January 22nd, 2010 at 19:20
I think this site was on this concept dating to at least 2006 and hence a bt before you Russ: http://www.die.net/earth/