John Gray on maps and cities.

A map can represent the physical structures of which a city is at any one time composed, but the city itself remains uncharted. This is not only because the city will have changed materially by the time the map appears. A map cannot contain the infinite places that the city contains, which come and go along with the people who pass through them. The map is an abstraction, simplifying experiences that are incomparably more variegated.

From The Silence of Animals. John Gray

Leeds Data Thing, Maps and Hackdays

Leeds Data Thing is a new group started in Leeds  (not to be confused with Leeds Ruby Thing!).

I spoke at the first event (read the write up from Rebecca) about Geospatial visualisations and  OpenStreetMap: Here are the slides:

Since then there has been a few other events as part of Big Data Week – including a load of great short talks.

This weekend there was a data hackday at the UK’s NHS Information Centre for Health and Social Care in the centre of Leeds.

hipster photo

There’s a wealth of data on their website , but it was given to us as a mysql database, and we were able to enter remotely. On the first day I poked around the data and had a thought.


I often spend the first part of any hackday wondering what to do, and twiddling thumbs. I find that hackdays become for me a type of busman’s holiday – and this hackday was particularly geographical in nature. Most of the entries had some kind of data on map component. I think that these types of analyses, whilst being very smart and interesting – and may be exactly what the judges are looking for, may not exactly stretch the unexpected or “the hack” in the data.

Fortunately there was plenty of latitude for exploring things laterally. The most interesting dataset was listing the chemicals and drugs each practice spent money on – but I couldn’t find much to do with it.   What caught my eye was the dataset listing the names of the doctors surgeries, practices, medical centres. If I think about my neighbourhood I can pass about half a dozen doctors in a very small area. Leeds is well covered (or perhaps just my area is!) . I was reminded of James Joyce’s quote about being unable to cross Dublin without passing a pub. Perhaps the same can be said for Leeds and doctors!  The names of the surgeries were also interesting. Names such as:

Chapeloak Surgery
The Avenue Surgery
Dr Ca Hicks’ Practice
The Dekeyser Group Practice
The Highfield Medical Centre
Chapeltown Family Surgery

Wonder if the more “leafy” the name, the more “leafy” the neighbourhood it was in? Perhaps the more grandiose sounding practices had more patients? Perhaps the smaller sounding ones had better patient satisfaction reviews?

At the venue, it appeared that I was the only one to be using Linux on the desktop and so the wifi did not work – so I had a bit over one hour to put something together. Decided to go with the concept of “Leeds is covered” and wanted something showing the labels of the practices over the areas where they were. Filling out the map, so to speak.  The hack was called “Tim’s One Hour Data Challenge” and here is the end result:

Leeds is covered

Leaving GeoIQ/Esri. Retrospective and future plans.

I’ve been with GeoIQ (the folks behind GeoCommons) since the Summer of 2010, and I’ve loved it. Earlier this year GeoIQ joined with Esri and we were hugely excited to change things from the inside and coming up with plans for the new Esri DC Dev team.. However, that’s all behind me now, alas, as it was time to move on. I have left GeoIQ/Esri to be a freelancer and to join the Topomancy coop. This post will take a quick look back at time well spent, and will touch upon what I will be doing in the future.

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Pubs in England – geographical distribution of names with cardinal points.

This image shows 4 maps of pubs in England where the pub names have a cardinal direction in the name. North, South, East and West. You can try searching for any pub name here.  For example, West = “The Great Western”, “The Westbourne”. North  = “Northcote Arms”, “The North Pole”

There appears to be more North pubs in London than anywhere else, and more West pubs in the north (and north west?) of England… running on a faster, newer server! has finished maintenance work – I really should get rid of the beta sign now. Anyhow its running on a much faster site, courtesy of So performance should be better now. All user accounts and maps and points should have been transferred seamlessly. georectify maps georeferencing fun!

I’m still configuring the mail server, so if new users when signing up are seeing mail in spam boxes, let me know!


268 Different Colourful Tiles – Plain Tile Maker

Plain Tile Maker was my weekend project – a mapping tile service that serves one colour tiles as a tile basemap.
There are about 268 colours to choose from – basically anything that the underlying library (Imagemagick) supports.
It was developed for me to play around on the Heroku platform, and as a response to a user question, where the user wanted a way to show just a plain one colour background.
This solution is more flexible, and really easy.






The format is

So for example,

And in return you get a 256×256 sized image of that colour.



You can use it in your mapping libraries, for example: With OpenLayers:

var colourTile = new OpenLayers.Layer.XYZ(
 "Plain Colour Tile",
 { sphericalMercator: true,
 buffer: 1,
 numZoomLevels: 17

And with Leaflet:

new L.TileLayer('{x}/{y}/{z}.png', {maxZoom: 18});

Or you can add them to GeoCommons quite easily. Add{X}/{Y}/{Z}.png

in the Add a URL link, choosing Map Tile URL from the format, and  then give it a nice name when prompted.

Here’s the Bisque tiles in GeoCommons.

I’ve used the in a map it to give a ghosting effect over the basemap, and to just show my own boundaries.  is a map made with some World Boundaries over the plain bisque map we had just added. I’ve also overlaid the Acetate Labels layer on top for context.

Want to know more? The code for this is on github.

Why companies are moving away from Google Maps to OpenStreetMap –

At Leeds digitial networking event LSxCafe this Tuesday, I talked about how companies, such as and are moving away from Google Maps and choosing OpenStreetMap. The slides are below.

Today the twitterverse and blogosphere were abuzz with the discovery that Apple had made the switch to use OpenStreetMap in their iPhoto application. At the moment, it appears to be so, but there’s no attribution yet. Compare for yourselves :  But take it from me, I have personally surveyed using a GPS unit and mapped paths in woods which are not on any map anywhere else (not legal footpaths) which appear on Apples map.

Pubs in England: How to do it with Polymaps and GeoCommons Filters

UPDATE: now using 27,416 pubs from Aug 2012

In this post I will show one way to display and interact with data from GeoCommons, using the powerful “filters”, and all on the mapping library, PolyMaps. It will show a basic example showing points on a map based on a filter and a more advanced example with changeable filters and some basic interaction on the points.

Few weeks ago, I wrote about how to display data from GeoCommons quickly on an OpenLayers map. The resulting little map was not that interactive, but it showed how easy it was to get started using GeoCommons as a data source. PolyMaps is a bit different than other libraries – it’s very lightweight, fast and powerful, but in terms of bells and whistles, you have to roll your own, like with Jquery core and all the plugins. It follows JQuery in another way, in that it uses method chaining. Anyhow, here is a map of Green Map named pubs in England. The base dataset, of all (24 thousand or so) pubs in England, was from OpenStreetMap, and the data is cc-by-sa. England pubs OSM july 2011  I added the data from an extract from

GeoCommons Filters

The GeoCommons API gives more information, but the filter we are using looks like this:[name][][like]=green%20man

filter[string_col][][operator] = text

We can use things like equals, min and max for numeric and date type attributes, and equals and like for string. We can also add more than one filter to the query.


Green Map pubs in England

Filtered GeoCommons features on polymaps.



Most of the gubbings is in the pubs.js file. Lets see what’s going on here.

The first section sets up the map, and adds the Acetate basemap to it, and adds a control to it. Notice the method chain:  “map.add(po.image().url(po.url ” pretty nice, eh?

var po = org.polymaps;

	var map_div = document.getElementById("map");

	var map =
		.center({"lat":54, "lon":-3})

The second section gets json from GeoCommons, based on a filter. A filter is like a search parameter. Then we can see that a layer is created and the features from the json are added to it.  We have to get the json outside of polymaps as the json is not quite valid GeoJSON yet – (it doesn’t wrap the features array in a featureCollection) – but no matter, polymaps can handle it.

var url =   ""+

    url = "/cgi-bin/proxy.cgi?url=" + escape(url);

    j = jQuery.getJSON(url, function(data){

Pretty basic, really, and not clickable, and the points are black. The points are SVG – and are default formatted.

Adding More Functionality

Search for any pub name, click on point gives the name.

This example lives at and the key part of the javascript lives in


We will be building upon the last example a bit.

We have refactored the adding layer bit, because this time we are making several requests. We give it a reasonably random and throwaway id, which we assign to a global variable of the currentLayerId, so we can delete it in the future.

function addLayer(filterText){
  if (currentLayerId){
    element = document.getElementById(currentLayerId);
    if (element) {
      var parent  = element.parentNode;

  var guid = Math.floor(Math.random()*3000);
  currentLayerId = guid;

  var url =   ""+

  url = "/cgi-bin/proxy.cgi?url=" + escape(url);

  j = jQuery.getJSON(url,
      map.add(po.geoJson().id(guid).features(data).on("load", setFeatures))


When the features are added, there is a callback method (setFeatures) which stuffs the name of the pub into the point’s SVG, gives it a CSS class so we can style it with pubs_styles.css, and add a mousedown event

function setFeatures(e){
  for (var i = 0; i < e.features.length; i++) {
    var feature = e.features[i];
    feature.element.setAttribute("feat_name",; //give the element an id
    feature.element.setAttribute("class", "pub_point"); //set css class for colours
    feature.element.setAttribute("r", "5"); //radius of svg circle.

    feature.element.addEventListener("mousedown", function(e){  
      clickFeature(this, e);	
    }, false); 


pub_styles.css  –  the fill is purple, the stroke, white and the opacity 0.6 – we style the features using CSS!

.pub_point {
   stroke: #fff;
   fill-opacity: 0.6;

The click / mousedown event function gets the SVG feature and the event, and displays a div whose contents is made up from the feat_name attribute from the featrure. function setFeatures(e){
function clickFeature(f, evt){
  var blurb = "<div class='info_blurb'>" + f.getAttribute("feat_name") + "</div>";

  var infowin = document.getElementById('infowin') = "200px"; = "200px"; = "auto"; = evt.clientX + "px"; = evt.clientY + "px"; = 'absolute'; = 'block';
  infowin.innerHTML = blurb; 

So, wastefully using just bit of JQuery to handle to form, when text is entered in the box and the button pressed, the current layer is removed, and a new one is requested, give it a go!

It’s basic, in that if you change layer, the text label may still be there, and the labels don’t move when the map is panned, but hopefully you can see that you would have to roll your won stuff on top of polymaps to do this.