Matt's Blog

Mappy Christmas!

A mappy Christmas and geolocated New Year to everyone!

No, this isn’t a real map, unfortunately
I created this in JOSM, imported it using osm2pgsql and rendered using my vector icons patched version of mapnik. (Note to self: release these patches, finally…)
Cheers!

2 comments December 21st, 2008

Expiry

Here is a short script to expire tiles based on osmchange diffs. Michal’s comment got me thinking about if there were an easy way to do it and today’s answer is yes, as long as you don’t mind it not being 100% accurate.

The script basically takes all the node locations in the diff, or referenced by ways in the diff, and expires the (meta)tile which contains that point. There are several problems with this approach:

• If a named node (e.g: a pub) is on the corner of a meta tile and its name is modified then the tile(s) containing the name should be expired as well.
• The non-local effects of mapnik’s text placement mean that changes to a way may affect its neigbours, meaning they should also be expired.
• If a way crosses the corner of a meta tile, but has no nodes within it, and is changed then that meta tile should be expired.

However, it seems to work well enough for me at the moment, although I reckon it is probably prudent to expire all the tiles every week or so, just to make sure.

Or the script can be easily extended to expire all the neighbours of expired meta tiles.

Add comment September 12th, 2008

5 Facts

Steve infected me with a post 5 things that people don’t know about you meme. Ordinarily I wouldn’t go in for this sort of pyramid scheme, but maybe this would be sort-of fun.

So, the 5 things:

1. Steve and I go way back. It seems that we’ve both changed a little since then
2. My favourite author is Isaac Asimov and I had read all the science fiction he had written before I was 16. When it was reported in the news that he had died, it was the first time I’d recognised a name in the obituaries.
3. Despite the above, my favourite book is Joseph Heller’s Catch 22, the only book that makes me laugh out loud every time I (re-)read it.
4. In an average week, I travel more than 214 miles by train, 38 miles by bus, but drive 0 miles by car.
5. My brother and I used to collect and paint miniatures (all the well-painted ones are mine!) but I was never very good at actually competing with them.

Since I don’t have five friends with blogs, I’m just going to tag Rachel.

Add comment January 5th, 2007

Anniversary

Well, its been over a year since my first post, but I didn’t notice. Never mind, there’s always next year

Add comment November 6th, 2006

Infamy

Finally, my great work is on display for the world (well, LinuxTAGers anyway) to see!

To be honest, I feel a little ambivalent towards the design: Its too busy, uses too many colours, doesn’t scale down to low resolutions. And, at the end of the day, it doesn’t really communicate what OSM is all about.

The problem with trying to represent the idea or concept of a free global street map is that the two main themes, “free” and “map”, are inherently difficult to explain visually. The visual language icons is surprisingly complex, but at the end of the day reduces to pictography – i.e: you draw simplified versions of what you see. For example, the Chinese character “人”, meaning man, does look something like a man. (see more and the evolution of the character at the Wikipedia page).

See also the 50 ideograms of the AIGA symbol signs. Of those, only five don’t in some way represent pictures of what they mean: First Aid, Information, Parking, No Entry and Exit.

So the concept of “free”, being an abstract noun, is quite hard to picture. The meanings, both intended, of gratis and freedom are in themselves hard to draw. How do you show “no money”? Freedom is even harder – it represents a lack of barriers and restrictions. Typically, when designers need to include some icon of freedom they’ll turn to cultural artefacts, such as flying doves, the statue of liberty, national flags, which don’t translate well internationally. One of the better known, and very well-designed, logos is the Amnesty International logo, but sadly I can’t crib this as the logo itself has little to do with freedom

A map is also very difficult, because the map itself is a representation of reality. So the icon would be a representation of a representation of reality. Clearly, its easy to lose the message along the way! We couldn’t use map symbols, as these vary from country to country. I’m sure if the OS hasn’t copyrighted them yet then it soon would. The quintessence of “map” is very hard to pin down – clearly an aerial photograph doesn’t have “map-nature”, but LandRangerâ„¢ does and so does the Tube Map. It seems to me that “map-nature” is as abstract as freedom, even though a map might be a physical object.

To conclude: I’m not particularly happy with my design for the OSM logo, but I don’t have any better ideas… Maybe someone else will?

1 comment May 10th, 2006

Spring rituals

In byegone ages there were rituals to mark the coming of spring. The local one in Reading (Abbey) was the singing of “Summer is Icumen In“. Or, at least, thats the one I was forced to sing at school. In most places there were harvest festivals and the like, dancing, getting very drunk, etc…

In modern times (if we’re lucky enough to even notice the difference between winter and spring) we’re as likely to just complain about how long its taken to arrive, or how lacklustre it is now it has arrived.

Having nothing better to do on an Easter Monday, my parents and I went for a walk down by the canal (NOTE: this is rural, so the canal is actually a nice place to be, unlike the canals in Paddington) and tried to enjoy the nice weather. Well, the reports said it would be nice and that there would be some sun. I have to admit, there was some sun, in between the bits that were cloudy and windy and quite cold.

Weather being one of the staple topics of British conversation, you’re probably not finding this post very interesting. But it was interesting to me to remember what I thought spring used to be like; when it suddenly got warm and the sun shone and things started to grow (and we were forced to sing “Summer is Icumen In”…)

But maybe this is one of those cynical, growing-old things. I’m sure I noticed spring more when I spent more time outside, rather than in the office. Most of the exposure I get to the sun these days is walking to and from the canteen at lunchtime (providing the observations for the lunchtime discussions about the weather, obviously ). Or, maybe, I notice it just as much, but find it more difficult to get excited about the slow turning of yet another year.

If you got this far looking for some sort of a point… sorry. Its all just rambling drivel, thats why it is posted under “random”!

1 comment April 17th, 2006

The Prophecy

Good Night, And Good Luck is a great film, which everyone should watch! It has clearly been brought out to make a point, but its a point that needs to be made: Has television become a medium for the pacification of the masses?

Given that the film is mostly biographical, with a lot of quotations and even real footage of Senator McCarthy, there is a surprising prescience to the words of Murrow. For example:

This instrument can teach, it can illuminate; yes, and it can even inspire, but it can do so only to the extent that humans are determined to use it to those ends. Otherwise it is merely wires and lights in a box.

Oh, and how pretty the lights are…

I like to think that its different in the UK than in the US, because one of the BBC’s “values” is education. But I’m probably wrong, because what we actually watch is just a stream of imported programmes from America without any educational content at all…

Another great morrow quote is:

We cannot defend freedom abroad by deserting it at home.

Presumably, this was included in the film as a direct jab at the “war on terror” and its continuing effects on our basic civil liberties. (Which is happening in America too.)

1 comment March 12th, 2006

Weird Light Effect

I noticed this on the plane to Zagreb. The cloud cover just beneath us seemed to have this strange colour pattern that was tracking the plane, so I took a picture. The first is the original, the second is a zoom to the feature.

I can’t decide whether this is caused by light diffracting through the density fluctuation caused by the aircraft and/or its engines, or if its something else entirely. The sun was directly behind the camera, so its definitely not lense flare or anything like that…

1 comment January 31st, 2006

Zagreb

I’m currently in Zagreb, Croatia on business, attending a conference about OpenFOAM, a cool toolkit/library to do CFD and other finite volume physics.
The city strikes me as similar to the southern French style, architecturally. I think it looks a lot like Toulouse, but with a hint of Italian.

Its also very, very cold and I’m hoping that I haven’t come down with some sort of illness, because I feel terrible. It might just be dehydration, since the Croatians don’t seem to drink water. Very strong coffee and soft drinks, but not water.
Also, they seem to have trouble with the idea of vegetarianism, but that didn’t really surprise me. Most mediterranean cultures seem to see meat at the “centre” of the meal, so eating nothing but vegetables probably seems very odd from their point-of-view…
However, the (very opulent) hotel has free WiFi, so its not all bad

1 comment January 26th, 2006

Seattle

I’m currently in Seattle, attending the Supercomputing 2005 conference. After arriving on Saturday, this is the first day that I haven’t actually been jet-lagged out of my skull. So, in my short time here, I’ve noticed a few things…

Seattle is full of:

• Tall buildings
• Starbucks (there is one per block)
• Homeless people
• People who, although they aren’t, look like they’re homeless…

And some environmental observations: its cold, much colder than Bristol, despite being at roughly the same latitude.

1 comment November 16th, 2005