Location finding for augmented reality

[1dude1]

So after talking about it with some future partners. We are looking to do something in the future. not this year, probably not next, but maybe within the next ten. I have had this idea since 2008 and now the technology is almost there.

i'm looking to either build or buy a location system capable of being as accurate as possible, EXCESSIVELY so. it needs to support at least 20,000 users and help them all find VERY accurate location information. the size of the area is about 1500m x 500m, all one level, very minimal interference(line of sight from one corner to the other) Needs to be closed loop. I will delete the info after it is done, the location will not move or change size. I would like accuracy down to less than 1mm throughout the whole field. but I could totally get it to work with 5-10 cm, just wouldn't be perfect like I want. system must be capable of generating location then sending coordinates to the users device so that the power isn't constantly drained from their devices, or should be able to, can make due without/if not possible.

So I know I sound new to this, and I am. But I am motivated to get this all done as well as possible. Everything worth doing is worth doing right. Sorry I can't give out more details about it. We all decided to keep our mouths shut about it thus far.

what is the most accurate, high distance, very high user count location system that I could either build or buy?

Thanks for any suggestions!

 

[etudiant]

Centimeter accuracy is routinely achieved with inverse GPS signals, where a mini GPS range is established using ground based repeaters. It is used for missile and aircraft testing and is well established technology.
Call Rockwell or Trimble for quotes.