Friday 28 February 2014

Floods of Transient Data

OpenStreetMap was not conceived as a platform for storing transient geographical data: traffic jams, road works, road closures, earthquake damage, barricades in city centres or floods. However it is used widely for holding such information for all cases except the first.

The recent flooding in Britain has led to a degree of questioning about how we should hold such data, but it has also reawakened an interest of mine in seeing if OpenStreetMap data can be used for simple modelling of hydrological systems.

First I discuss transient data and look at a different aspect of flooding, the availability of suitable data, in the second part of this post.

Flooding in the Somerset Levels mapped on OSM
using key natural=water
copyright OSM contributors, CC-BY-SA

Friday 14 February 2014

Diversity isn't always what we think

Yesterday I had to find a Western Union outlet to receive a money transfer from a friend who lives in a country where he cannot enjoy the normal financial service amenities we have in Europe and North America.

Western Union outlet in Hyson Green
Source: OpenStreetView

It was an eye-opener. There are lots of these outlets locally. I was aware of them, but had never considered that the availability of money transfer facilitates was worthy of mapping.

Having had to search for locations on-line and noticing that the information even on the Western Union site is  out-of-date in places I have changed my mind. For shops with a Western Union or other money transfer outlet I am using money_transfer=Western Union. Standalone premises can be tagged amenity=money_transfer as suggested on the OSM wiki.

This experience reinforced my own awareness that, however conscientious I am in trying to map things, my decision about what to map is heavily affected by my own experiences. Although I am strongly aware that Nottingham is a city with people from all over the world (how can I not be, our immediate neighbours are from Africa and Asia). This has been reinforced when mapping shops, restaurants and takeaways. Similarly, although I have a friend who makes a living out of offering telecom services to Bangladeshis living far from home, and have noticed how many shops have Lebara branding, I'd never thought about how this sort of thing should be mapped.

In a recent post I mentioned that I worry that tagging of woodland may act to reduce the diversity of mappers in terms of interest and expertise. This is just another example of how increasing diversity within OpenStreetMap is not just about extending involvement from different groups, but also recognising that different people have a variety of needs when it comes to things which get mapped.

A part of getting involvement from different groups is showing that OSM is relevant to them directly, rather than as a substitute for Google Maps. We've achieved this for wheelchair users in large part because of the involvement of Sozialhelden, and tactile maps have received a lot of attention because user Lulu-Ann has consistently championed them for a long time. Champions such as these have extended the horizons of every OSM mapper. (It doesn't have to be an obvious diverse theme, either, bahnpirat championed the mapping of power lines, which turns out not to be as geeky as it seems). The most obvious OSM champion, is Mikel Maron. His passion and action in taking mapping to marginalised communities ultimately led to the Humanitarian OSM Team, which is now a significant actor across the globe within the humanitarian sector.

I therefore think that increasing diversity in all its forms within OSM means nurturing our past, present and future champions. These people can help everyone see things differently.

Tuesday 11 February 2014

Exemplar locations for woodland mapping: 1 Garrotxa

In order to get a better idea of the issues involved with my more detailed suggestions for tagging woodland, I've been searching for suitable locations which have a range of different woodland types, and data available on the woodland types. For reasons I've discussed previously I'm restricting this examination to the Holarctic region.

Cap on anem? // Which Way?
Fayeda d'en Jorda, Beech Wood in Parc des Volcans, Garrotxa

In the main I am looking for data sets either held on a national or regional level. To ensure comprehensive coverage this pretty much means looking at official datasets.

Fortunately most countries in Europe, the US , Canada and Japan have over recent years collected a lot of useful data under national forest inventory programmes. Other sources are comprehensive vegetation surveys, carried out by national biodiversity conservation bodies. Only a fraction of this data is readily available on-line, and might not be in a readily digestible form.

To date I have selected a small number of places. Most areas are mountainous so as to have a broader range of woodland types in a smallish area. Areas which are transitional between broader biomes also increases the heterogeneity. The first I describe here: the area of the Volcanic Natural Park around Olot in Catalonia.

Hunting Woozles in a 10 billion acre wood, .. or is that forest

This post is the first part of a series amplifying my talk at State of the Map 2013: "Zone de Combat".

Rather like Winnie the Pooh and Piglet wandering around Hundred Acre Wood in search of imaginary woozles we have been going round in circles in the woods. Or is that forests?

Infrared photo of Cottonwoods in Utah exposes hidden beauty of woodland
Cottonwoods by arbyreed, on Flickr CC-BY-SA

We have a little more than 40 hectares of woodland to care about: there are about 3,425 million hectares of woodland on the globe, covering around 23% of the total land area.

Since I got involved with OSM, 4 and a half years ago I've seen the mapping of many other objects has achieved a very fine level of detail. We can lovingly worry about the minutiae of mapping busbars in power sub-stations, or whether pubs have stone floors and real fires, or which king or queen was alive when a post box was built, or the number of flames in gas lights. These demonstrate that we are perfectly capable of mapping a lot of detail.

On the other hand there are many things where we have failed to delineate important distinctions when we map them. This is particularly true for woodland where we have two widely used tags which are virtually synonymous (landuse=forest and natural=wood). The problems have been rehearsed endlessly on the Wiki, and on OSM Help, so we have a pretty good handle on them, but there has been little concrete action. I think we have argued too long about the respective semantics associated with forest and wood. And, by the way, I'm as guilty as anyone else.

To coin a phrase "we have not seen the wood, or forest, for the trees".

Friday 7 February 2014

Looking for footpaths in Hickling Notts

I thought I'd follow up my post about the Foolow Hole with an account of an early morning spent last Spring searching for public rights of way in south Nottinghamshire.

Old-fashioned fingerpost at T-junction S of Hickling
Public Rights of Way (PRoW) in Nottinghamshire are much more poorly mapped on OpenStreetMap than those of Derbyshire. It is safe to say that paths as a whole are much less well mapped let alone checked to see if they are Rights of Way.

Sunday 2 February 2014

Mapping a Hole

I don't get to do much countryside mapping these days, so when I learnt that my sister and friends had rented the Youth Hostel at Bretton it seemed like a good idea to pay a visit for the day. My motivation was that just before Christmas Day a very large hole had appeared in a field close by (~ 800m).

Sinkhole from Bretton Ridge:
© Copyright Graham Hogg and licensed for reuse under this Creative Commons Licence.