March 26th, 2014
Satellite Metadata Archive in Video
You might find yourself asking what is so sexy about our satellite metadata archive? Most commercial satellite providers host a metadata archive to help prospective customers and resellers discover imagery products that meet their search criteria. Customers are often interested to know the solar and collection angles, cloud cover percentage, date, resolution, etc. to help them decide on a scene to order. See - I told you this was going to be good!
While designing the Skybox Search archive, we compiled all the satellite metadata we could get our hands on (1986-2012) to use as test data before the launch of SkySat-1. To help us better understand the history of commercial collections, I recently started creating maps of interesting queries from this database. The most basic question is how many times have we imaged every part of the world:
The answer is somewhere between 0 (black) and 15,000 (red) times per 10x10km area, with notable hotspots in Asia, Europe, and North America. What is somewhat surprising is that most of Eastern Asia is imaged orders of magnitude more frequently than anywhere else on earth. This is especially interesting when you consider that this trend appeared in the past decade (we’ll get to that a bit later).
15,000 times sounds like a lot but we know some of these scenes might not be too useful. What we are really interested in is the number of collects that are at most 50% cloud covered and better than 2m resolution:
The colors might look similar, but the scale has been adjusted to show a range of counts between 0 (black) to 20 (red) per 10 x 10 km area. In the most heavily imaged parts of the world, this works out to a couple of good collects per year. This really exemplifies the dearth of available high resolution satellite data, precisely the problem we want to fix with our constellation!
I quickly discovered that there were a lot of interesting trends that could not be depicted in a single image, so I switched strategies (and color schemes) and decided to make a video of the history of collections where each frame represents 1 month of collects from the archive (see the date on the bottom right). I used a heat map color scheme to illustrate counts of 0 in black and 10s of scenes in yellow/white.
Watch the video in 1080p HD resolution on the following YouTube link. Click on the 1080p HD and full screen toggles to see the video in its full resolution.
Now things start to pop! The video really comes alive in the 2000s when the SPOT constellation was joined by several new companies (DigitalGlobe, GeoEye, RapidEye etc.). You can see some interesting trends in political events and a resulting the shift away from interest in North America and Europe and into Asia and the Middle East around the same time. Additionally, you can see the strong seasonality to requests especially in the higher latitudes. Points form around dense urban areas, and larger swaths cover areas known to be rich in natural resources such as timber, oil and minerals.
If you still aren’t convinced, and are ready to move on, Google Taiwan... according to this data, it's the most interesting place in the world!