Mark W. Eichin wrote:

number like "1 foot resolution" -- and then did some processing on a photograph to demonstrate what that meant.

The picture used was a rear view of a VW Bug, with a copy of Isvestia resting on the upper edge of the trunk. Basically, you could tell there was something sitting there, but you couldn't read the headlines

A previous poster suggested 1 inch with the latest technology on a clear day. In any case this has grave implications for the privacy in outdoor activities like under-the-sky-copulation. A simple protection is available: a heat source to produce chaotic air turbulence. A campfire?

A couple of years ago, IEEE Spectrum did an article which took the premise that spy-satellite optics could be made that were as good as the Hubble Space Telescope optics (for various reasons, pointing

July 1986. Most of the issue was devoted to articles on "national technical means" for verifying arms control agreements. This has always been jargon for spy satellites and other not-so-public capabilities. Phil

From: tcmay@netcom.com (Timothy C. May)

Could the same effect (as a segmented mirror) be achieved by taking multiple pictures (from the same mirror) and processing them together? E.g. does synthetic aperture radar actually produce higher resolution than achievable from a single "snapshot"? If so, then this might work (at least for slow-moving targets :-)...

dat@ebt.com (David Taffs)

Yes, but the positional accuracy required (on the order of the wavelength) would be prohibitive to achieve. (Such things may be possible for the NRO's DSP (more acronym overloading: DSP stands for Defense Support Program) satellites to implement. I haven't heard any speculations that this is actually being done.) Synthetic Aperture Radar is feasible becuase the wavelengths are so much larger. The new Keck Telescope will eventually use a second telescope, now under construction, located some distance away, for very long baseline interferometry...I have no idea if it can be made to work as an actual synthetic aperture. Jay Freeman man know. I wasn't thinking so much of interferometry techniques (although my reference to synthetic radar certainly implies them), but rather something on the order of a filter which might work (independent of the wavelength of light) as follows: Take, for example, the square box pixellation (is this the right word here?) used to blot out people's faces on TV sometimes. Put a long (preferably continuous) series of images into the computer, and build a model of the movement of the person's head (the camera isn't perfectly still; assume that the person, however, does stay still). Use the data about how adjacent pixels change over time to improve the model of what the person's face really looks like. This is independent of the wavelength of light -- it does of course depend on the resolution of the square pixels used to blot the peron's face, but not particularly on the wavelength or resolution of the camera (assuming it is much better than the square blotches). I first noticed this effect watching Court TV's coverage of the William Kennedy Smith rape trial (I was home sick at the time), while the victim testified. I felt that as the person (and camera) moved around, I could gradually form a better opinion of what the person looked like than just provided by the square blotches, by noting when and how the (macro-)pixels changed. Of course, just filtering a single frame would be better than looking at the sharp-edged squares. I'm talking about averaging all these filtered images over time, compensating for movement of the camera and subject. It would seem to me that over long enough time, perhaps using more sophisticated mathematics than just averaging (although just plain averaging seems like the right operation here), if there was actually enough movement to provide enough resolution, you could eventually get to a real photographic-quality image of the person. This process might be similar to CAT scans, where a lot of low-resolution "pictures" are combined to create a high-resolution image, except the distribution would be temporal rather than spatial. ObCryptoJustification: I think is relevant to c'punks, because it involves decryption of an encrypted signal (recovering the face of a person when it was intentionally distorted). Does this mean that if people like Court TV really want to blur people's faces, they need to add crypto-secure noise instead of just averaging the micro-pixels into macro-pixels? I think so! ObRandomOtherThreadWithMarginalCryptoJustificationButInReplyToOtherCpunksMsgs: and also ObAdditionalMetaDiscussionAboutWhatIsAppropriateForThisList: I also thought the license plate joke was definately relevant to c'punks, because it was actually a code, where the cleartext domain was conceptual rather than textual, just like this mail talks about a domain in 2-space (or 3-space) images, rather than text. Also, the fact that the "plaintext" was actually a pun involving multiple coding schemes made it relevant to this list also IMHO. Also, I think short humor is appropriate for any list, at least if it is both funny and computer-related, but I admit that may be stretching it for some here. I assume that coding (as distinguished from ciphering) is indeed relevant to this list... -- dat@ebt.com (David Taffs)