At a technical level, I was reminded of my Cooltown colleagues’ Websign project, which had the very similar core functionality of a mobile device with integrated GPS and magnetometer, plus a set of web services and a markup language for binding web resources (URLs) to locations with control parameters (see also: Websigns: Hyperlinking Physical Locations to the Web in IEEE Computer, August 2001). It was a sweet prototype system, but it never made it out of the lab because there was no practical device with a digital compass until the G1 arrived. Now that we have location and direction support in production platforms, I’m pretty sure this concept will take off. Watch out for the patents in this area though, I think there was closely related prior art that even predated our work.

Anyway I looked carefully at all the demos from Layar and the various online coverage, and wondered about a few things:

• Layar’s graphical overlay of points of interest appears to be derived entirely from the user’s location and the direction the phone is pointed. There is no attempt to do real-time registration of the AR graphics with objects in the camera image, which is the kind of AR that currently requires markers or a super-duper 3D point cloud like Earthmine. That’s fine for many applications, and it is definitely an advantage for hyperlinks bound to locations that are out of the user’s line of sight (behind a nearby building, for example). Given this, I don’t understand why Layar uses the camera at all. The interaction model seems wrong; rather than using Layar as a viewfinder held vertically in my line of sight, I want to use it like a compass — horizontally like a map, and the phone pointed axially toward my direction of interest. This is most obvious in the Engadget video, where they are sitting in a room and the links from across town are overlaid on images of the bookshelves ;-) Also, it seems a bit unwieldy and socially awkward to be walking down the street holding the phone in front of you. Just my $0.02 there.
• How will Layar handle the navigation problem of large numbers of active items? The concept of separate “layars” obviously helps, but in a densely augmented location you might have hundreds or even thousands of different layers. Yes this is a hard UI/UX problem, but I guess it’s a problem we would love to have, too much geowebby goodness to sort through. I suppose it will require some nicely intuitive search/filtering capability in the browser, maybe with hints from your personal history and intent profile.
• Will Layar enable participatory geoweb media creation? I’d be surprised if they don’t plan to do this, and I hope it comes quickly. There will be plenty of official corporate and institutional voices in the geoweb, but a vibrant and creative ecosystem will only emerge from public participation in the commons. This will demand another layer of media literacy, and this will take time and experimentation to develop. I say the sooner we get started, the better.

In any case, good luck to the Layar team!