Responding to msg by pierre@shell.portal.com (Pierre Uszynski) on Mon, 19 Sep 6:32 PM

What would be ideal in all these cases is a steganographic process that would map to the whole as much as to the parts. Fractal steganography. In the case of architectural drawings, a signature of the original architects would be embedded in small sets of dimensions, in small sets of proportions, in ways the CAD language is used, in the background details of artwork, in the text included in drawings as well as in CAD files comments and variable names... etc... In summary in sufficiently numerous and different places that mechanical modification, or even extensive manual rework could still forget some instances of the signature.

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But, for legal issues, how would that be different from copyright registration? Doesn't copyright registration rely on the same principle: a set of jurors will determine what the chance is that this is the same work or not. This just provides tools to fortify a court case.

Pierre, The fractal steganography sounds promising. Is this yours or has it been done? The need for authentic sigs on architectural and engineering drawings is not merely aesthetic. Right now municipal agencies will not accept digital documents because of the lack of verifiable authorship to establish responsibility, and liability, for the health and safety of the design and construction. Hard copy with original seal is required to prevent unauthorized manipulation. Beyond copyright protection, architectural and engineering documents are means to guide actual construction, rather than end products like paintings and drawings in the art world. If there could be a way for buildings themselves to convey authenticity, say, that they are healthy and safe, by a kind decryption by the public that could help prevent concealment of shoddy construction. It's not the drawings that assure safety but field verification of the end result that construction work was done right. What a great help if a building could convey its own message of authenticity about its fitness and safety for habitation and use. That might keep us architects more honest. Probably a long shot that your fractal idea could be stretched this far, but it is certainly needed in the flim flam world of New York City real estate where deception about building safety and health is all too common. Any other thoughts? John