That's understandable, would it be useful to have a library from another region for comparison?

Yes. Based on the English library on trains other well developed countries including likely sources of trains include Japan, China, South Korea, France, Mexico, and Germany. Although Asia has the highest population density and if that's a factor in scanning it might be better to get those humans as scans and rescue physical ones from elsewhere.

Density does make scanning somewhat easier overall, though it does make it more likely I'll need to do deduplication before recreating people.

Oh?

The way that density makes scanning easier is if I start scan areas that contain people instead of individual people. Scanning a volume in one sweep is faster than scanning that volume in smaller specific sections. There is however little guarantee that the same person won't occur in two such areas if I'm distributing the scanning over a long time period for stealth reasons.

Aha. Yes. Is deduplication difficult?

I don't expect it to be for most purposes, especially given that we only have two weeks of outside time to operate in. My understanding is that outside of cases of major injury or sudden illness most humans will not change significantly in that time period.

Apart from some memory loss, that's my impression too.

The fact that memory loss is routine is troubling. It's one of the reasons I'm confused why some people would prefer not to have the mind-speech and the deep-dream. 

I have a lot of memory blessings, although they don't add up to quite perfect. There are varying opinions on perfect memory among Elves who have improvements readily available. I'm not sure how humans stack up but it would surprise me if their memories were invariably perfect, but I am confident it's not customary to lose two weeks outright.

Oh, you were referring to the memories of the intervening time. I meant significant changes which would make it difficult to recognize two scans of the person as being such.

Oh. Yes, that seems unlikely. You could wake up the later ones first and ask them if they remember where they've been in the previous possible scanning times.

That is roughly my plan to handle cases where I'm uncertain. I believe that I'll be able to distinguish between identical twins based on circulatory system layout and similar differences but that would be the sort of thing which would lead to uncertainty.

That makes sense.

Your house is done, at least to the extent that I can replicate it from your memory. My cameras don't have quite the same properties as your eyesight. I'd be happy to revise it if you tell me specifically what needs revision. I didn't include mind-speech interfaces in it. I can add the option to speak with me from anywhere to your computer or I could make you a ring or similar with a seperate interface, strictly for mind-speech no cameras or other sensors.

A ring would suit.

Will this suit? There's an image of the blue crystal she's accustomed to carved like a gemstone with an octagonal face and set in a filigree pattered like trees on four sides with the filigree and band made out of platinum.

Yes, that's lovely.

A robot appears in the usual way carrying the ring. Now that there are more places to go, I added the ability to set the teleporters' destination to your computer. Right now they'll go here, the biology lab with the dogs and to a structure closer to your house. I tried to match the aesthetic of your house for the latter.

She dons the ring. Thank you.

You're welcome. I like doing nice things for people.

You've been very hospitable.

Would you like to do more reading, examine your house, continue trying to get closer to decisions about how to retrieve and house humans or some combination thereof?

I'll check over the house and then if changes need to be made they can happen while I read more.

Time passes and decisions are made. Finally the day of the teleportations arrives. Sapphire has successfully scanned two and a half billion people so far. A collection of subway-riders find themselves arriving at a very different station than they were expecting. The station is brightly lit and immaculately clean. There are murals of natural vistas on the opposite wall the supports for the arched roof are embellished to look like trees. The ceiling is painted sky blue and has soft but comprehensively illuminating lights set into it. The doors open and the train announces "This train is being taken out of service please exit the car."