Re:DigitalGlobe: 30cm satellite imagery
by gregsadetsky on Saturday March 14, 2015 @02:19AM
(#9201715)
Yes, there is a theoretical limit -- the "Rayleigh criterion".
http://en.wikipedia.org/wiki/Imagery_intelligence#Satellite
"This means that it would be impossible to take photographs showing objects smaller than 16 cm with such a telescope at such an altitude. Modern U.S. IMINT satellites are believed to have around 10 cm resolution; contrary to references in popular culture, this is sufficient to detect any type of vehicle, but not to read the headlines of a newspaper."
superresolution to the rescue, as long as your lens, or the target is moving you are golden
There is also going to be some sort of limit based upon the atmospheric correction that needs to take place to get that sort of accuracy. Light is going to travel (bend) differently through different atmospheric conditions like temperature, pressure, and even composition of the atmosphere in that area. There is also reflectance issues based on the surfaces that are reflecting the light. Clouds and snow are extremely reflective and will need to be corrected for as well in order to not miss out on other parts of the image.
I think this may be less of an issue now than in the past with all of the cloud computing capabilities out there, but they still to develop the techniques.
And are they able to get higher resolution using some other tricks?
And are there limits on the size of civilian satellite payloads vs military payloads? Is there a theoretical limit to resolution that spy satellites have based on lens size?