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[Accidentally sent this to Jon only - meant for the whole list]

 Thanks Jon for the detailed reply. Now that I understand what you mean
about a non-linearized playback, I see that the "virtual stylus" I
mentioned is still a step or two below the possibilities of extracting
sound from a high-detail 3-D model of a groove using non-linearized
analysis of the groove. This will be especially true with worn discs,
which are usually worn in differenent ways in different parts of a disc.
And I certainly hope that your optimistic assessment of the
technological situation is true.

  And to reply to Sam's comment, of course he is correct that there are
many different opinions in the Library and mine is just one. Also, I
hope that no-one misunderstood me as speaking in any official way for
the Library. Situated as I am in a powerless position at the LOC ;) , I
forget that others may not realize this as fully as I do. And in fact, I
agree with Sam that there may be some uses for 2-D disc imaging, but IMO
I wouldn't extend those uses to routine preservation.

James



Disclaimer: Opinions expressed are personal and are in no way related
to official Library of Congress policy.

>>> Jon Noring <[log in to unmask]> 09/24/03 03:40PM >>>
James L. Wolf wrote:

> Just wondering. Once the processing and storage capabilities for 3-D
> modeling of a groove arrive (10+ years?), wouldn't it also be
possible

Personally, I think we are there already. Disk space is not an issue,
so we can collect and process huge amounts of information, a
prequisite
for doing full 3-D topography of a record to the resolution needed.
And
as I noted, it would surprise me if there isn't already a surface
topography measuring system or device (probably using lasers and
suitable for our needs) being used right now in the research
establishment for some purpose. It's amazing what technologies are
routinely being used at the National Labs (and many industrial labs),
many of which have not been commercialized. Even if the specific
device hasn't yet been developed, there are probably people (the trick
is finding who) at the National Labs or at universities, who could put
something together rather quickly. I don't see this as being a big
issue, having worked in the National Labs for almost 15 years.

To me, the biggest issue is writing the code, with the requisite
computer algorithms, to analyze the 3-D topography and therefrom pull
out the recording -- to "virtually" play the recording and derive the
best possible signal from the topography of the grooves. This will NOT
be trivial. The one nice thing is once a 3-D topography is stored and
archived (probably on MO disks), then as the digital "play-back"
algorithms continue to improve over time, we can revisit earlier
topography data without need to re-scan the rare original record.

...[original message truncated]

Jon Noring