Building the Android mobile prototype app for Bomb Sight

Since my last blog post giving a technical overview, the Android app has come along nicely and the second prototype is now being developed further into what will become the version of the app we release.

Development of the prototype continued using the Phonegap framework – allowing for possible future porting to the iPhone – and is using the Javascript-based Leaflet mapping library for the map view rather than the Android-specific library we had used in the initial prototype.

A quick walkthrough

When you load the current version of the app, you are shown a quick introduction and then invited to view the map when you are ready. The map is showing the data from approximately the first 8 months of the Blitz (October 1940 to June 1941), including the type of bomb that fell at each location.

If you are in the London area then the map will zoom in to your current location and highlight it with a marker in amongst the bomb markers. If you’re not in London (or if we can’t locate you) the map will zoom to a view of Greater London which gives you an impression of the vast number of bombs that fell during that period. If you’ve moved the map around, you can always zoom back to your current location using the crosshair icon underneath the zoom controls.

When you’re zoomed in to a small area, we show you a map with markers that depict the type of bomb that fell at each location. If you’re zoomed further out then we simplify the icons so they don’t just end up covering the street layout on the map.

The augmented reality view shows you markers hovering over where bombs fell, scaled to show closer locations with larger markers and smaller ones for those further away. For some more contextual information, where we can, we add a label with the name of the street it fell on. If you click on the marker, you’ll get a bit more information about the bomb and how far away from your location it fell. The associated radar dot will also be highlighted so you can see where it is in relation to others showing on the display.

Prototyping and iterative improvements

As I’ve been building the prototype I’ve been regularly testing it out, including taking it out around the streets around where I live. Along with helping me find out more about the area I live in. Also the user testing At The National Archives  in October raised a number of questions and possible issues with the app…which we are now looking at.

Because we are currently relying on getting data from the project website rather than shipping it all with the app, the app can sometimes take a little while to load the data, and it will be using up your data allowance as well. In the coming weeks we’ll be looking to reduce the amount of data transfer required by stripping out information we don’t need, and possibly by shipping some of the data with the app so it doesn’t need to be transferred over the phone network once you’ve downloaded it from the app store.

There are currently issues with performance of the map when we’re showing a lot of information on the map, so we will be working to make this a bit easier for the phone to handle by simplifying how the data is displayed and not displaying any more information than is needed.

With the augmented reality view, we started off showing a simple icon for each bomb with a label underneath to show how far away it fell from where the user is currently standing. From testing this out and about on the street, it was clear that this didn’t give a very good experience as it wasn’t easy to tell where the markers referred to. This is how we came to changing icon sizes and trialling address labels to help users contextualise what they are seeing.

When there are lots of bombs that fell in a certain area, the screen can become quite full, so we will be trying a number of techniques to try and help the situation out here. The screenshot below shows a trial of slightly translucent markers to let users see markers in the distance as well as the closest ones, but it may be that it adds more detail to the screen than is necessary. What do you think? Do the address labels add to the confusion too?

On the subject of augmented reality, when you’re trying to overlay information in an exact location, you need to make sure you know exactly where the user is, and which way their phone is pointing. This can be a bit problematic at times if your location hasn’t been detected accurately (e.g. if you’re under trees, near tall buildings or away from wifi networks), and may mean that what you’re seeing on the display doesn’t actually reflect reality. Over time as your phone refines its location, the display will update to correct this, but it may still lead to some confusion initially.

I will try to mitigate some of these issues in the final app by checking location accuracy (and currency, if you’ve walked on a bit since your phone last detected your location) before showing the first display of data, and perhaps try showing a small map of what we believe the user’s location to be.

I’ll post again when the app is available for wider testing, but why not tweet us @BombSightUK if you’d like to be an early tester.