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UrtheCast Releases Its First Commercial Videos of Earth
schwit1 writes: UrtheCast has released high resolution videos of three Earth cities taken from its camera on ISS. Take a look. The cameras are quite successful in capturing the motion of vehicles on highways and road, which is amazing considering the vibrations that ISS experiences merely from astronaut movements. Quartz reports: "The company plans to offer the imagery in several tiers, from a free video feed on its website to an API that will allow customers, including corporations, governments and individuals, to purchase imagery data from its database or make real-time requests for a look at a given spot on the earth. The cameras scan the ground under the ISS, which tracks the earth between about 51 degrees north and south latitude."
It appears that individual cars are at just about the spatial resolution of the camera. Figure a car is something like 2 meters by 5 meters. Urthecast's camera, 'Theia', is advertised as a 5-meter camera (5m x 5m on the ground). So a car only takes up about half of a pixel. Which means that when the CCD is exposed, sometimes the pixel comes out white for a white car that happens to align itself totally within one cell of the CCD, and sometimes the car 'disappears' when it is overlapping two cells and is not increasing either cell's reflectance enough to make the cell come out white. (Note also that we only really see white cars; if you look very closely you may be able to see darker colored cars also, but they mostly blend into the road because they are not differently colored enough).
Theia is also a 'pushbroom' camera, which means that its CCD array is a linear array that is swept over the field of view (likely with a mirror or similar). Furthermore, the camera itself is moving through 30 degrees of arc while focusing on one area of the Earth, which means that as the CCD is imaging each linear set of pixels, it's moving within a camera that is moving on board a space station that is moving with respect to the Earth. So there is a *lot* of image processing going on to turn this collection of pixel rows into a coherent video. Some of that processing is likely to involve lossy processes and interpolation that provide a second source of this 'disappearing car' phenomenon.
> UrtheCast has released high resolution videos of three Earth cities taken from its camera on ISS.
So taxpayers have been pouring billions into the ISS so some company sticks a camera on it and sells you photos? Screw that. Should be public domain.
I thought it was a catheter company.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.