Scale and Resolution
 
This webpage is intended to give you an introduction to scale in terms of aerial imagery.  The word resolution means different things to different people in the field of geography but in the world of remote sensing spatial resolution boils down to pixel size.  Learning what you can see at what scales is something you gain only from experience, this is especially true with air photos.  The more photos or images you look at the better idea you have of what kind of mapping or analysis is possible with what types of imagery and what the scale required is (called the "minimum mapping unit" problem).  Linked to this page are images of different scales and some info about military reconnaissance because there is reality and there is what's in the movies, sometimes it's a fuzzy line but when it comes to military intelligence imagery there is a limit to the spatial resolution.

Comparison
Image Size vs. Information
Centimeter Level
Meter Level
Atmospheric Effects
 
Corona vs. SPOT - Click to Enlarge
Comparison of Imagery from SPOT and CORONA Dimona Nuclear Facility in Israel September, 1971
1, 3, 10 meter resolution - Click to Enlarge
1, 2 and 3 meter resolution of the White House
Multi Resolution - Click to Enlarge
80, 30, 20 and 10 meter resolution

Pixel Dimension Graphics 1 | 2 | 3

Military Reconnaissance
High Resolution Imagery
Corona
Russian Spin 2 (Great Pyramids)

No, the government can't read license plate numbers or newspaper headlines from space. The laws of Atmospheric Optics make it essentially impossible to get better than 6 inch resolution from space and even that is pushing it in good conditions!