Augmented reality for Hursley mobiles

On Wednesday, Chris Book was kind enough to invite me to join the mobile developer panel at openMIC 3 : the third Mobile Innovation Camp.

The theme for the day was location and augmented reality.

A particular highlight was a talk by Paul Golding on Augmented Reality & Augmented Virtuality, covering a variety of topics such as the state of Virtual Worlds today, and the potential of mobile augmented reality apps to move us from a “Thumb Culture” to a camera-led “Third Eye culture”.

A number of mobile augmented reality platforms were discussed, such as Nokia’s MARA research project, the QR-based Insqribe, the real-world / virtual-world mobile mashup platform junaio, and the ‘world browser’ Wikitude.

Another platform that got several mentions, including a developer’s crash course in the afternoon from Richard Spence, was Layar.

I had a quiet afternoon in the office this afternoon, so I thought I’d give the Layar API a quick try for myself.

Layar is a mobile app for Android and iPhone that lets you display location-based information overlaid on a real-time camera view.

For example, the screen normally shows a viewfinder-like view from your mobile’s camera.

Search for “coffee” and a bunch of markers appear on the view, showing you where the nearest coffee shops are.

As you move the phone around, the markers follow the approximate location of the places they are showing you.

That’s assuming you want to search ‘Google Local’, but that’s not the only option. Location data is provided through “layars”, and there are layars available for location-tagged Wikipedia articles, Flickr photos, brightkite users, and more.

The interesting thing talked about at openMIC was the Layar API which lets anyone create a new Layar with their own information.

So I decided to spend a quiet Friday afternoon in the office creating a Layar for around Hursley. 🙂

This means a phone with the Layar browser installed can browse and search for points of interest around the site.

It was really very easy, so I’ll quickly outline the steps involved.

Step 1 – Get an API key

Visit and click on ‘Request a developer account’.

Once approved (it took a few hours), you get a developer ID and key.

Step 2 – Define a new layar

Once you’ve got an account, go back to and fill out the ‘Create Layer’ form, describing the layar you want to create.

There are a ton of options here. These range from the obvious like a name, description and tags to display to users choosing a layar to use, to neat customisations like uploading custom colour schemes and icons to use as map markers on the phone screen.

I just filled in a brief name and description and left the rest as the default values.

Step 3 – Define a source of Points of Interest (POI)

Layar wants to support real-time location information.

A good example of this is the brightkite layar. Users choosing the brightkite layar see a view overlaid with the current location of their friends or other brightkite users.

To make this possible, you don’t create a Layar by uploading a static database of points of interest.

Instead, you have to provide a web service that Layar can query to get current locations. (When defining the new layar on the dev website, one of the steps is to provide the URL of where you will put this web service.)

The API doc for this web service is at and details the parameters that your web service will be invoked with (e.g. the user’s current location), and the format for the response that your web service must return to Layar.

The Layar browser does perform client-side filtering to only show markers relevant to the user’s location. However, if you are writing a Layar like the Wikipedia one, it’d be best not to just return your entire database of POIs, burning the mobile’s battery both in the data transfer and the processing needed to do the filtering.

For my quick first test, I was a bit lazy and ignored the input location parameter and just return all of my Hursley POI markers regardless, leaving the mobile to do the filtering.

Parameters are provided as URL variables, and the response format is a pretty straightforward JSON interface.

It took no time at all to knock up a quick bit of PHP to return this…

$currentLat = $_GET['lat'];
$currentLon = $_GET['lon'];

$place1 = array('actions'=>array(array('uri'=>'',
                                       'label'=>'view on map'),
                                       'label'=>'phone now')),                
                'title'=>'Main Reception',
                'attribution'=>'ETS demo',
                'distance'=>distance($currentLat, $currentLon, 
                                     51.026570, -1.397964),

// <snip> ... bunch of other places here ... </snip>

$allPlaces = array('errorCode'=>0,
                   'hotspots'=>array($place1 ,$place2, $place3, 
                                     $place4, $place5, $place6, 
                                     $place7, $place8, $place9),

echo json_encode($allPlaces);

Obviously, hard-coding all of the locations is a sloppy way of doing this – in a real system, you’d want the PHP to be retrieving this from a data store of some sort.

There is open source code available from a bunch of places to get you started in doing this – PorPOISe looks like an interesting example.

Interestingly, the mobile client doesn’t calculate the distance from the user to the POI – you have to return that from your web service call. This is the only reason why I didn’t just write a static text file with JSON data for my “web service”, as I had that one dynamic bit needing to be changed.

The other bit worth highlighting is that each POI can include one of more “actions”, that get offered to the user if they click on a point of interest on their mobile. I added a few examples such as launching a web page or making a phone call. E.g. you can see where Main Reception is on your screen, and choose to call Reception if you want.

Step 4 – Test the web service

It took a couple of tries to get my PHP right… mainly because several of the parameters described as optional in the API doc are actually required 🙂

Fortunately, there is a nice test service available at

You plug in your developer ID and key, give it a location of where your mobile should be, and click “Load POIs”.

It tells you what is wrong or missing with the JSON response it gets back from your web service, which for me was either which required value was missing, or a numeric value that I was returning as a string. The errors are clear enough to help you fix your service.

Step 5 – Try it for real has a link to the installer for the Android app.

This app is a developer version of the normal one available in the Android Market.

(If you already have the normal app installed, you need to uninstall it first. I didn’t, and the developer app didn’t work properly until I uninstalled and started again).

The developer app gives you extra options in Settings to provide your developer ID and key. This lets you access your unpublished layar for testing (until approved by Layar, your new layar isn’t available to other users).

(It also lets you override your phone’s current location – useful for testing indoors!)

Once you’ve done that, your new layar shows up in the mobile’s list of “Featured” layars.

(I found that it only showed up if I also changed the Country setting from “Auto” to “GB”… not sure why, although when I defined the Layar, I did specify that it was a GB layer.)

And that’s it… I had a fun excuse to go wandering around Hursley this afternoon to test it out and collect the screenshots for this post. 🙂

2 thoughts on “Augmented reality for Hursley mobiles

  1. A great post and glad you are picking up AR and doing stuff with it on eightbar 🙂
    I was playing with Layar the other day. The Flickr geotagging layer is a great one too. When I was at Southampton Parkway station I took a few pictures on the iphone and geotagged them. One of them was my feeding edge business card. Left floating in the air there 🙂 I hope I see an eightbar gang sign left there next time I travel 🙂
    Interestingly the Layar guys are busy
    putting 3d in too.
    It starts to merge many of the things we have all been talking about in a very neat way 🙂

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