Segmentation of Retail Landuse: why do Germans only map shops?

Retail Landuse in Karlsruhe on OSM (scale 1:50k) :
both explicitly mapped and derived landuse polygons are shown, see below for methods.

The availability of lots of open data on various kinds of retail outlets has led to me doing a lot of maps of shops, restaurants, fast-food outlets and bars lately. I'm following in the steps of Paul the Archivist who mapped the Mansfield Road area close to pub meetings we had in 2011. I've got a nice workflow : I map my target area for an hour on Sunday morning, usually trying to get all retail establishments in a quite small area. I also try and collect as many house numbers as I can. I discovered my new mapping protocol, because my mother asked me to drive her to church a few weeks ago and I found it very productive. It also means I've been actively surveying in a neglected inner-city area.

Maps for Dogs, or Lamp Posts in chains

Wet Lamp Post, photo by Don3rdSE (all rights reserved)

Not more stuff on street lights, 'fraid so.

In my earlier post I mentioned that it would be nice to see if it was possible to find the location of streets simply by linking together all the lamp posts on the same street. This is a (technical) account of how I achieved this using PostGIS.

Lamp Posts to Addresses: gold dust in the attributes

Local Government Open Data 4

I'm so used to a lot of open data being poorly attributed that I did not look at the Nottingham street light data until I'd imported it into PostGIS. Apart from lacking the asset identifier, and having redundant fields for the x and y positions of the geometry, it has two fields of fantastic value for enhancing OpenStreetMap.

Lenton Sands area of Nottingham showing House Numbers from Lamp Post data overlaid on OSM

Street Lights: Local Government Open Data 3

Another data set released by my local council contains the locations of all the street lights owned (or operated) by the council. Now I have no intention (or any desire) to import this data into OpenStreetMap. Is it any use in the open data context?

There are two obvious questions that can be asked using street light data:

• How well mapped are all public highways (i.e., including footways and cycleways) in the city?
• Are the highways on OSM accurately mapped?

Street lights are spaced at specific intervals according to the type of highway, it's width and the nature of the light source. This means that their accurate placement is determined by the council beforehand, all location data is to the nearest metre. Since most lights are situated immediately adjacent to the road carriageway they will be a short distance from the road centre line (say under 10 metres).

It is trivial to buffer the network of highways from OSM (via a Geofabrik download) and then use geometry operators to find all lights within the highway buffer envelope, and all outside the envelope. Using a very simple constant buffer of 10 metres I obtained the following result:

Street lights which are not close to OSM roads (best viewed large).

Local Government Open Data 2: Checking for Completeness

My second look at Nottingham City Council's open data, is a very recent release : "Licensed Premises". I've also changed the title of the post as I believe that the topic, issues and conclusions I draw are relevant to  sources of local open data anywhere.

Ye Olde Trip to Jerusalem - Nottingham

© Copyright Richard Hoare and licensed for reuse under this Creative Commons Licence.

I'd hoped that this would be solely concerned with the sale of alcohol as this would enable a good cross-check against mapping of pubs, bars and restaurants. However,as well as licenses for sale of alcohol on and off the premises, it includes categories for licensing of musical performances, boxing, wrestling. late-night sales and several other things.

Nottingham Open Data 1 : CCTV Cameras

It's amazing how much difference a couple of years makes in the availability of data under open licenses. My local council, Nottingham City Council, now has at least 40 different data sets available, and more are appearing all the time.

Of course not all of them are useful for improving OpenStreetMap.  However, many of them are.

SPECS Speed Camera, Arnold Lane, Nottingham

I've spent a bit of time in the last month playing with these data sets, and thought it was worth sharing some thoughts about how such data could (and should) be used in the context of OSM. As there are a range of quite different data I'll discuss them in a series of posts, with conclusions at the end of the series. Somewhat quirkily I'll start with CCTV Cameras.

Persistence in the Urban Environment : 1

Anyone reading this blog should have realised that I am interested in using maps to understand how the environment we live in has changed over time. I know I share this interest with many other OSMers. There have been many proposals, and discussions about how we might use some of the principles and technologies of OSM to create maps representing an area at some historical time point. I am greatly heartened that a new mailing list (http://lists.openstreetmap.org/listinfo/historic) has appeared for interested parties to share ideas on this subject:

Wollaton Park Estate from the E, (June 1928)