Londoners! A reminder about various London events coming up TOMORROW (Saturday 24th):

• Spacemakers Brixton mini mapping party - Let's get more people along with their laptops. Should be fun.


• Open Knowledge Conference including a little talk on OSM in Haiti.


• Or there's also the Witham mapping party if you fancy a journey out of London

Just had to mention that before I describe last Wednesday's mapping evening and pub meet-up in Holborn, which was quite eventful.

We had along a couple of interesting people (not that I don't find the rest of you interesting you understand) :

Adam Mullineux who works for TfL joined me from the beginning for a mapping demonstration. I was doing my thing of checking building outlines which I'd sketched in from Yahoo the night before. I did a lot of talking and explaining to try and make this rather tedious task more interesting, but talking at the same time as mapping is actually quite difficult.

In the pub we had Stuart Carter, Corporate GIS Manager at Southwark Council, who is going to be using OpenStreetMap for some of their public facing online mapping. ITOworld are helping them set-up some custom rendering, so that sounds like it's going to be a fantastic bit of OSM usage. Stuart is also very interested in engaging with the OpenStreetMap community and finding ways of giving back. Of course meeting people down the pub is rather an informal setting for talking about GIS futures with local council people. In some ways I'd prefer to be wearing a tie and ushering Stuart into a swanky glass-fronted OpenStreetMap office for this kind of discussion, but of course OpenStreetMap will never be like that, and the sooner Stuart realises it the better! I started a wiki page "UK local councils", partly because Stuart asked me to, but partly because I've been meaning to write a document targeted at local councils for a long time. It should probably be a PDF download with an ostentatious title including the words "white paper", but this sketchy wiki page is all I've had time for so far, so feel free to flesh that out with more ideas.

Speaking of local councils, James rutter has been doing some tantalising tweets about aerial imagery for Surrey, and Andy Allan showed up with a USB stick bulging full of data from him. This will be plugged directly into the UCL servers (dev) but there's a question around how we should serve up the imagery. Some on-the-fly tile slicing may be needed, because it's starting to be too much image data for pre-slicing and storing as static tile images on the filesystem. Anyway... Hi-res aerial imagery for the whole of Surrey coming soon!

(More photos on flickr)

We had a visit from Steve stylesheet Chiltern and Jon mod_tile Burgess, so there was extensive discussions around Mapnik rendering. Jon explained that the reason mapnik layer coastlines are not currently updated very regularly is to do with the linear pipeline nature of the processing, ending with a shapefile. There is no easy way to feed more regular diffs into the final shapefile, it has to just run all at once as a big end-to-end number-crunching operation.

We mentioned some "Natural Earth" free datasets, and Steve said it might be nice to use this at low zooms, to give a more attractive/interesting overview of the planet with a little bit of releif showing.

More tile server related discussion. Firefishy wants to get squid working more effectively with tiles. There's a need to tweak the HTTP headers to provide information about whether a tile is served from disk or rendered on-the-fly.

Meanwhile at the other end of the table there was some discussion about getting OpenStreetMap stuff into the ubuntu apt repository, and Andy was saying he's learned a lot more about evil undocumented quirks of OpenLayers than he ever wanted to.

So lots of awesome discussion washed down with wetherspoons real ale festival booze, and on the way home we came across some posters for Nike grid (nikegrid.com) the thing Ollie Obrien blogged about.

Think I need to blog about this myself too, but yeah. OpenStreetMap is on posters all around London! Rock on!

Phew! Now scroll back up to that reminder about London events tomorrow.