Years ago, I saw a library that said it was planning to use "Bulk RFID" scanner to assess the need to manually reshelve books on a given shelf, and/or find misreshelved books. By "Bulk RFID" scanner, I mean that the books are not scan one-by-one, thought the relative locations of a book to its neighbors is known.
Does this work, and if so, why does it appear this not commonly used in RFID enabled libraries?
blunders
According to Mick Fortune's 2012 survey of RFID use in libraries worldwide, about half of all libraries using RFID at all also use handheld scanners for inventory/stock management. 58% of all Australian RFID-using libraries do, as do 55% in the UK and 48% in the US. The rest of the world has not yet seen as much reason to use RFID for finding misshelved items; only 29% of libraries elsewhere take advantage of that benefit.
So I'm not sure why it appears ... not commonly used from your perspective, but this survey suggests that among RFID-using libraries, using a handheld scanner for finding misshelved items is fairly common.
I found an article from the Chronicle of Higher Education where they describe a smartphone app that can read a shelf of books to see that they are shelved correctly. Is this more along the lines of what you were asking about? It uses QR codes rather than RFID but it is still pretty interesting.
The app he came up with, tentatively called Shelvar, relies on special tags—kind of like QR codes—attached to the books’ spines. Each tag “exactly represents the call number” of each boonkman explains. A user with a current-generation smartphone or tablet computer scans the shelf using the app, and Shelvar indicates which books aren’t in the right places. Visual cues, including directional arrows, indicate where the misfiled book ought to go.
http://chronicle.com/blogs/wiredcampus/shelving-made-easy-or-easier/30792
As far I am concerned, this is a hardware question. I don't know of any mobile hardware that can do, say, reliable, complete and nearly instantaneous mass-perception of 5,000 unmoving items (a few shelves' worth) from the basic RFID tags commonly used by libraries.
It isn't inconceivable, but it is a completely different problem than the rapid serial detection of RFIDs passing through a controlled aperture. Would be happy to see a counterexample if one exists.
Shelf order is an even more difficult problem. To detect a misshelved item, the hardware would need to be able to triangulate the location in 3-dimensional space. All location information would be based only on signal strength and triangulation. There isn't anything else available!
So it is hard for me to see how a "bulk scanner" would be accurate to the fraction of an inch required to say "this two books should be swapped". Variations in book dimensions, cover thickness, RFID location inside the book, shelving, etc. are all greater than the granularity of resolution you would be trying to obtain. (That's assuming you can even isolate all the responding frequencies from each other when you're hitting thousands of them simultaneously.) It would be one thing if we were talking about standardized mechanically-tagged, mechanically-positioned containers. We aren't. We're talking about human-tagged, human-shelved items that have been exposed to the Dark Agents of Chaos otherwise known as "users". File me under skeptical.
While we reportedly do have such a thing, I have been told that it wasn't considered very successfull at finding dislocated items. It cannot check the shelf for sorting criteria, it can only identify to the level of location information available from your database. If you decide to carry this location information down to single shelves, you will be punished by having to update that information each and every time you're shuffling books around to make space for more.
So while you might be able to check for misplaced books from other (sub)libraries or shelf divisions, that's about where it ends.
Now, when we'd start lending magic gadgets to patrons who are desperately searching their overdue library books within their vast stacks of printed paper of seemingly endless appartments, RFID based location might become popular indeed ...
