How complete is Open Street Map?

OSM is a great project and as it gains in coverage it becomes an increasingly attractive proposition. One of my former clients in Local Government was excitedly talking about the potential to use OSM for some of their partnership projects, which prompted me to look at OSM in a little more detail.

Take a look at these two similar scale images of Highgate, North London from OSM and Google.

OSM

Google

The OSM version has some footpaths and also includes the railway line which Google does not show, plus in my opinion the cartography in OSM is the nicest I have seen of any web maps (I know that is not their raison d'etre but it is still nice). Unfortunately when you look a bit more carefully you will see that there are some small streets missing and some of the road name attribution is different to the TeleAtlas data in Google. I have highlighted a few differences below but have not searched for all.

In Google

and in OSM
Now OSM is a community project and I don't think they make any claims about completeness or accuracy of attribution. However those of us in the GeoCommunity who consider using OSM in a project or who promote the development of crowd sourced data need to be aware of its potential limitations. Unfortunately at the moment there is no way that I can see to guage the level of completeness of OSM which seems to make it a bit of a lottery.

At AGI GeoCommunity08 there are a couple of potentially very interesting sessions on on this topic from Andy Coote and Nick Black

GeoCommunity08 - Early Bird Contdown

One week left to register for the early bird discounts for AGI GeoCommunity08.

The bookings are filling fast and the offer will close on 31st July (or earlier if the main hotel is fully sold out) so book now

Pinpointing Crme

Heather Brooke in the Guardian last week suggests that the reason crime statistics are not published at a very detailed level by the Met is because they are concerned about being held to account for crime:

Knowing what crimes happen and where is important for several reasons. First, people want to know how safe (or unsafe) they are. They need accurate and detailed data if they are to form an opinion of the safety of their neighbourhood. When they know what's happening, they are in a better position to help or support the police. They are also better able to hold the police to account. This is perhaps what the police fear most...

Perhaps this is oversimplifying the issue. There has been much discussion within academic and police circles about the anonymisation of crime statistics, what precisely would constitute adequate anonymity? Is just leaving out the victims name but providing precise address details sufficient? Remember that a unit postcode in urban areas represents about 12 houses, would it be ok to pinpoint a crime to that extent? Heather Brooke talks about mapping crime to "street level" - unfortunately defining a street for this purpose may not be as easy as it sounds, how would one distinguish between a cul de sac with only 4 houses and a major thoroughfare with several hundred? There may also be some crime types which need to be anonymised to a greater extent than others to ensure that no one can deduce the identity of the victim (or alleged perpetrator) from the apparent location shown on a crime map - family violence and child abuse for example might fall into this category.

Publishing information that can be de-anonymised (horrible word) through local knowledge for example could be counter productive and might indeed breach a victims right to privacy. The potential difficulties are not insuperable and I do not believe that the reluctance to publish detailed information by the police service is part of an effort to avoid being held accountable.

Perhaps what is needed is a carefully considered model of what information should be published at what level of granularity to protect the rights of the victim whilst providing useful information to the public. One for the Jill Dando Institute?

Cartograhy matters

The AGI and the British Cartographic Society have been running a series of events entitled Better Mapping.

I guess that many of us working in the GI space do not give much thought to cartography. In other words - what the maps look like does not matter.

I have often described what I did to people who did not understand GIS or software as being the mapping equivalent of making the CD player part of a music system whilst the maps and user content were like the CDs that you played on the system. Now if you hate opera then it isn't much fun having a state of the art hifi system and only having Wagner CDs (substitute your musical likes and dislikes)

Or to put it in our terminology, it doesn't matter how elegant or snazzy your web mapping application is if you then load it up with ugly maps that prevent you from communicating information effectively to your users. Imagine Google Maps loaded with OS 1:50k raster maps and you will get the idea.

Quick summary of the event -

• Cartography is a form of communication that should be simple, subtle and to the point.
  
• A map should have structure and graphical logic.
  
• It takes time and care to produce a map that is fit for purpose.

If you look at a map that you have recently published can you say that about it? If not have a look at the BCS web site.

The dangers of relying on your iPhone

Normally when I am going to a new address I will print out a map before leaving. I had to get to a seminar yesterday and had the address details stored in my online calendar which I thought I could access through my iPhone and then Google up a map when I came out of the tube station rather than printing. Unfortunately the wonder device was throwing a near windows like wobbly and could not connect to the internet so no access to Google Maps. Fortunately I was able to resort to the old fashioned technique of asking someone for directions.

Lessons learnt:

1. Don't be quite so dependent on technology
2. The iPhone is a bit like Windows, when it stops working switch it off and switch it back on again! Shame I only learnt that at the end of the day
   

Have you got money to waste?

The Early Bird not only catches a worm but it also gets a good discount on attendance at AGI GeoCommunity08. The offer runs out at the end of July or when all the rooms in the main hotel are booked (don't worry we have reserved rooms in several other hotels within a couple of minutes walk from the conference venue).

To quote Chris Holcroft, director of the AGI:

It has attracted leading figures, as speakers, from Ordnance Survey, ESRI (UK), Multimap, Microsoft, The Environment Agency, Defence Geographic Centre and many others including: Vanessa Lawrence, Charles Kennelly, Sean Phelan, Charlie Pattinson and Stuart Haynes. They will join a large group of well known presenters and commentators in the conference programme. There will also be a debate chaired by Jeff Thurston, an INSPIRE stream and panel discussion as well as workshops and 'hands-on' training.

Now you wouldn't want to miss all that would you? So if you don't have money to burn book now!

Gone fishing, left the building, moving on

Well that's it. After just under 500 days my time with MapInfo has come to an amicable conclusion.

The GDC team and product strategy are now fully integrated into MapInfo's business so now I can get on with the many other things that I have wanted to do for a while. Could be more neo than paleo but only time will tell. For the time being I want to enjoy the summer, my new iPhone and a long overdue vacation.

Have got several blog bits to write that have been stored up and more time to focus on the AGI GeoCommunity '08 event in September

Now for the serious stuff - choosing a new bathroom

TA joins the crowd?

In a press release Tele Atlas announced a long term license deal with Google. Interestingly:

The agreement also gives Tele Atlas access to edits for its maps from Google’s community of users, whose suggested changes can help the company further increase the quality and richness of Tele Atlas maps.

I wonder how long it will be before Google starts to host a wiki like OSM and create its own data or just links up with OSM and hosts that?