Category Archives: Software

OpenStreetMap UCL mapping party

On the afternoon of Friday 2nd March I was at the UCL mapping party for the MSc students on a development planning course. In a similar style to Andy Allan on various previous occasions, I found it pretty interesting to see the various issues that the students came across when starting to use OpenStreetMap data for their course work.

Here’s a list of things that people had a problem with:

  1. If there is an error loading an invalid GPS trace into Potlatch 2, then Potlatch 2 just stalled during the startup rather than displaying a useful error message and continuing to load.
  2. Many of the users when working in advanced mode managed to enter a value, and with the way that they clicked somewhere else before entering the value, which meant that the key would disappear and confuse users.
  3. It would be nice to be able to give a nice notice when a user enters a key or value in sentence case when lower case would be expected.
  4. It is very hard to select a node at the end of a way.
  5. There was confusion about the 3 editor options in the menu that drops down from the Edit tab.
  6. The lack of accessibility mapping features in the presets made it more difficult to get them up to speed quickly.
  7. Building entrances are missing from the presets.
  8. How are people supposed to know to shift click to add a node in the middle of a way.
  9. Potlach2 can’t handle more than one major feature at a time, for example a building and a place of worship.
  10. No highway crossing preset.
  11. Easier setup of custom Potlach 2 with custom MapCSS. Maybe some form of GUI to create those files?
  12. How do you take a scanned map and put it as a background?
  13. Many people had questions around why the detailed data they were adding wasn’t showing on the map, for example why were disabled parking spaces not showing up with a specific disable parking space symbol in Potlatch 2.
  14. The help font size in Potlatch 2 is a bit on the small side, thus can be difficult to read for some users.
  15. After creating a GPS trace in an app on the mobile, how to get it and the photos into the editor.

WordPress London Meetup – 17 November 2011

On Thursday 17th there was the November WordPress London meetup in the Headshift | Dachis Group offices. I recorded the 3 presentations and have uploaded them to YouTube:

WordPress News by Chris Adams

Chris gave a roundup of the latest changes and releases in the WordPress community. [Updated video with typo in title fixed.]


WordPress Site Structure for SEO by David Bain

David gave an introduction to setting up WordPress for good SEO practice.


Using Custom Post Types by Keith Devon

A technical talk by Keith on how to create a new custom post types.


London WordPress Meetup – 28th July 2011

On Thursday there was the July 2011 London WordPress meetup in the Headshift | Dachis Group offices. I recorded the presentations and have uploaded them to YouTube:

Ice-breakers & Introductions

Introduction to WordPress by Emily Webber

Beginner Theme Development by Keith Devon

Looking Under the Hood of WordPress by Chris Adams

If you’d like to come along to future meetups, please join the London WordPress Meetup group.

OpenStreetMap Shortlinks

Shortlinks were introduced to OpenStreetMap at the end of June 2009, by Matt Amos, as a way to have a short url to get to a specific point on the map. It is a method to go from the code to a latitude, longitude and zoom. It also works in the reverse direction too. You will see the shortlink in the bottom right hand corner of the map on If you have a location that you want to show to people, say on twitter, then the shortlink may be a nicer method than using the standard tinyurl services.

Here is an example of the difference:

You can even add markers by appending ?m to the end of the short link and the marker will appear in the centre.

If you are a developer you may want to include support for the shortlink, in addition to or instead of the standard permalink. A good example is if your app sends twitter messages with your current location, where there is a limited number of characters that can be used, thus a shorter url is needed.

For some code take a look at the bottom of the site.js file, site_controller and the shortlink library.

Update: With the move of the OpenStreetMap codebase having moved from svn to git the new file locations are: sites.js, site_controller.rb, and the ruby shortlink library.

Installing ImageMagick on Snow Leopard (64-bit)

This blog post is only relevant if you are on Snow Leopard, have a 64-bit Intel Mac, and need to install ImageMagick.

There are many Ruby on Rails projects out there that have some form image manipulation, thus use ImageMagick for that. Up until recently it was a real pain to install, with some huge list of library dependancies that need to be downloaded, compiled and installed. The ImageMagick project is now supplying a Intel 64-bit binary, specifically for Snow Leopard user so that they don’t need to install from source.

Another nice little tips that I learned for installing gems that have native extentions, is that you can put the ARCHFLAGS environment variable into your ~/.profile so that you don’t have to manually set it (and then wonder why the gem doesn’t compile elsewhere). You need to add:

export ARCHFLAGS="-arch x86_64"


Last weekend I was at Mashed08. I stayed there overnight, so didn’t get much sleep.

Didn’t do any mashing up, though I did finally start writing a bit of ruby code to take a file with a list of street names, and ask the OSMXAPI whether that street exists within a specified bounding box.
It was interesting to see what people were doing. There was very few people doing anything with maps. There were a few groups who using high resolution satellite imagery rather than plain old maps. A lot of people were working on something that was tv or audio related, such as ripping the subtitles and translating them into another language in almost real time. Twitter seems to be rather popular.
The event was featured in this week’s BBC News Click programme. (BBC iPlayer only works in the UK and programmes are only available for one week.)
I’m uploading the better photos to Flicker with the Mashed08 tag.
P1020874.JPG P1020881.JPG P1020869.JPG P1020892.JPG P1020899.JPG P1020919.JPG
When your at a station waiting on a delayed train, just get some bean bags out to sit on:
P1030112.JPG P1030115.JPG
(Kinda ideal for getting passers by ask were the bean bag sale is).


From the 10th to 13th April I was in Prague, Czech Republic for GoOOCon, an conference hosted by Novell.

I done a presentation about the Buildbot system in I didn’t have time to prepare new slides, due to my move to London, so I just recycled my slides from ooocon2007.
It was nice to see a bit of another country and to meet up with some of the developers in real life.

Device Removal

I don’t touch anything, and my slow first generation MacBook will randomly come up with the above message. Maybe an uptime of 13 days is the cause? 
It is about time I rebooted into Kubuntu to get some updated maps on to my phone for TMJ. There has some considerable improvements in the maps in Edinburgh, and I don’t know what actually needs to be mapped when I’m out in the field.

OOO: Possible fix for the command timed out error on Leopard

UPDATE:Thanks to Eric Bachard, a fix very similar to this will be appearing in 2.4.2 due to be released at the end of October 2008.

With a change in the way that X11 works on Leopard, the X11 version of has been giving an error message on startup saying “command timed out”. With previous versions of Mac OS X, had to make sure that X11 was running first be trying to start

The following change should work for 2.4, 2.3.1, 2.3, and possibly earlier versions. Open the file in “Script Editor”. (You will need to control+click the application icon and choose “Show Package Contents”.)
Then replace the code block “on openSoffice(aFile)“….”end openSoffice” with the following:
on openSoffice(aFile)
 if (atLeastOSXVersion(10, 5, 0)) then  
-- if we have leopard, we don't need to manually start the X server first
  set theCmd to "sh " & (quoted form of (POSIX path of getOOProgramPath() & "soffice")) & " "
  do shell script theCmd & aFile & shellTerminator()
  set theDisplay to startXServer()
  if (theDisplay is equal to "error") then
  end if
  set theEnv to "DISPLAY=" & theDisplay & " ; export DISPLAY; "
  set theCmd to "sh " & (quoted form of (POSIX path of getOOProgramPath() & "soffice")) & " "
  do shell script theEnv & theCmd & aFile & shellTerminator()
  -- logEvent("open CMD: " & theEnv & theCmd & aFile)
 end if
end openSoffice

Please comment on how this works for you. 2.4 on Mac OS X [Update: now available]

The release of 2.4 (X11 version) is a little behind the other platforms due to a lack of resources in the QA process, as many of the resources have been placed on the upcoming aqua version. It will be another few days to week before they are available on the mirrors and the Mac Port download pages will be updated at that point.

Until then the new smart download pages will continue to give the link to the 2.4.0 build which isn’t yet available.
UPDATE: X11 2.4.0 for both Mac OS X 10.4/10.5 PPC and Intel are now available from the Mac Porting Download pages.