Notes on how we ran the SuperCollider Symposium 2012

I've just uploaded my notes on how we ran the SuperCollider Symposium 2012 (10-page PDF). sc2012 was a great event and it was a privilege to work with so many great people in putting it together. I hope these notes are useful to future organisers, providing some detailed facts and figures to give you some idea of how we did it.

The document includes details of the timing of things, the budgeting, promotional aspects. I also include some notes about outreach, which I think is important to keep in mind. It's important for community-driven projects to bring existing people together, and to attract new people - and for something like SuperCollider which doesn't have any institution funding it and pushing it forwards, these international gatherings of users are 100% vital both for the existing users angle and the new users angle. Happily, both of these aims can be achieved by putting on diverse shows featuring some of the best SuperCollider artists in the world :)

Shout outs to all the other organisers, who put loads of their own time and enthusiasm in (see the "credits" page), and hi to everyone else I met at the symposium.

(If you weren't there, see also Steve's great photos of sc2012.)

Syndicated 2012-05-02 15:43:54 (Updated 2012-05-02 15:44:09) from Dan Stowell

Why power to the people

What should you strive for?

• Equal spread of power among all people.

Why? Three reasons, of which the third is the most important:

1. Morality: Equal power per person is fair.
2. Efficiency: Equal power is the most efficient way to make use of our combined human capacities.
3. Instability: Power begets power, which means that it tends to "clump" - equal spread of power is not a stable state. Thus we have to continually work towards it, rather than achieve it and then relax.

Syndicated 2012-05-01 09:05:50 from Dan Stowell

How I made a nice map handout from OpenStreetMap

OpenStreetMap is a nice community-edited map of everything - and you can grab their data at any time. So in theory it should be the ideal thing to choose when you want to make a little map for an open-source conference or something like that.

For our event this year I made these nice map handouts. It took a while! Quite tricky for a first-timer. But they're nice pretty vector PDF maps, with my own custom fonts, colour choices etc.

For anyone who fancies having a go, here's what I did:

1. I followed the TileMill "30 minute tutorial" to install and set up TileMill on my Ubuntu laptop. It takes longer than 30 minutes - it's still a little bit tricky and there's a bit of a wait while it downloads a lump of data too.

2. I started a new map project based on the example. I wanted to tweak it a bit - they use a CSS-like stylesheet language ("MSS") to specify what maps are supposed to look like, and it's nice that you can edit the stylesheets and see the changes immediately. However, I found it tricky to work out what to edit to have the effect I wanted. Here's what I managed to do:

   • I changed the font choice to match the visual style of our website. That bit is easy - find where there are some fonts specified, and put your preferred font at the FRONT of all the lists.

   • I wanted to direct people to specific buildings, but the default style doesn't show building names. However, I noticed that it does show names for cemeteries... in labels.mss on line 306 there was

         #area_label[type='cemetery'][zoom>=10] {
     

     and I can add buildings to that:

         #area_label[type='building'][zoom>=10], 
         #area_label[type='cemetery'][zoom>=10] {
     

   • The underground train line was being painted on top of the buildings, which looks confusing and silly. To fix this I had to rearrange the layers listed in the Layers panel - drag the "buildings" layer higher up the list, above the "roads" ones.

3. When I'd got the map looking pretty good, I exported it as an SVG image.
4. Then I quit TileMill and started up Inkscape, a really nice vector graphics program. I load the SVG that I saved in the previous step.
5. I edited the image to highlight specific items:
   • The neatest way to do this is to select all and put it all into a layer, then select the items you want to highlight and move them to a new layer above. Once they're in a separate layer, it's easier to use Inkscape's selection tools to select all these items and perform tweaks like thickening the line-style or darkening the fill colour.
   • Selecting a "word" on the map is not so easy because each letter is a separate "object", and so is the shadow underneath. If there's a single word or street-name you're working on, it's handy to select all the letters and group them into a group (Ctrl+G), so you can treat them as a single unit.
   • You can also add extra annotations of your own, of course. I had to add tube-station icons manually, cos I couldn't find any way of getting TileMill to show those "point-of-interest"-type icons. I think there's supposed to be a way to do it, but I couldn't work it out.
6. The next job is to clip the map image - the map includes various objects trailing off to different distances, it's not a neat rectangle. In Inkscape you can do a neat clipping like this:
   • Select all the map objects. If you've been doing as I described you'll need to use "Select all in all layers" (Ctrl+Shift+A).
   • Group them together (Ctrl+G).
   • Now use the rectangle tool to draw a rectangle which matches the clipping area you want to use.
   • Select the two items - the rectangle and the map-item-group - then right-click and choose "Set clip". Inkscape unites the two objects, using the rectangle to create a clipped version of the other.
7. Now with your neatly-cropped rectangle map, you can draw things round the outside (e.g. put a title on).
8. If you ever need to edit inside the map, Inkscape has an option for that - right-click and choose "Enter group" and you go inside the group, where you can edit things without disturbing the neat clipping etc.
9. Once you're finished, you can export the final image as a PDF or suchlike.

Syndicated 2012-04-22 10:11:21 (Updated 2012-04-22 10:25:33) from Dan Stowell

Implementing the GM-PHD filter

I'm implementing the GM-PHD filter. (The what? The Gaussian mixture Probability Hypothesis Density filter, which is for tracking multiple objects.) Implementing it in python, which is nice, but I'm not completely clear if it's working as intended yet.

Here's a screenshot of progress so far. Look at the first four plots in this picture, which are:

1. The true trajectory of two simulated objects moving in 1D over time.
2. Observations received, with "clutter" and occasional missed detections.
3. The "intensity" calculated by the GM-PHD filter. This is the core state variable of the filter's model.
4. Filtered trajectories output from the PHD filter.

So what do you think? Good results?

Not sure. It's clearly got rid of lots of the clutter - good. In fact yes it's got rid of the majority of the noise, hooray hooray. But the clutter right close to the the targets is still there, seems a bit mucky, in a kind of way that suggests it's not going to be easy to clear that up.

And there's also a significant "cold start" problem - it takes up to about 20 frames for the filter to be convinced that there's anything there at all. That's no real surprise, since there's an underlying "birth" model which says that a trail could spring into being at any point, but there's no model for "pre-existing" targets. There's nothing in the PHD and GMPHD papers which I've read which even mentions this, let alone accounts for it - I'm pretty sure that we'll either need to initialise the state to account for this, or always do some kind of "warmup" before getting any results out of the filter. That's not great, especially when we might be tracking things that only have a short lifespan themselves.

One thing: this is a one-dimensional problem I'm testing it on. PHD filters are usually used for 2D or 3D problems - and maybe there needs to be enough entropy in the representation for clutter to be distinguished more clearly from signals. That would be a shame, since I'd like to use it on 1D things like spectrogram frames.

More tests needed. Any thoughts gratefully received too

Syndicated 2012-03-29 17:00:13 (Updated 2012-03-29 17:03:11) from Dan Stowell

All Tomorrows Parties: Jeff Mangum

Just back from a fab All Tomorrow's Parties, this one curated by Jeff Mangum. As well as the bands, he curated quite an educational TV channel throughout the event - we got to learn about Chomsky, Zizek, the Bali islanders, oh and Monty Python on endless loop.

Some of the things I saw:

• Elephant 6 Holiday Suprise - best thing about that was the ending, when they played a Sun Ra song and then started to process off the stage, led by the sousaphone player and the saw player (the saw player sticking his saw in the sousaphone and banging it!) - they led us outside singing the Sun Ra refrain, "This here, our invitation, we invite you, to our space world"...
• Charlemagne Palestine played a wine glass nicely, but then when he settled into his long two-note piano tranceout it got really boring.
• Joanna Newsom - quite amazing to see her play. That surprised me, I know her music but seeing her playing live, the intricacy of the harp and her twisty twindy vocals is kinda mesmerising. It's less interesting when she's playing the piano.
• Matana Roberts and Seb Rochford did some delightful delicate free-jazz together. It's amazing watching Seb Rochford play, even when he isn't actually playing.
• John Spencer Blues Explosion - amen to that.

That was all on the first day, fantastically enough. The best things about day two were:

• Cream tea in town, with wortleberry jam, yum.
• Flumes in the Butlin's swimming pool. The "space bowl" flume was brilliant. Word to the wise, if you're ever there...

Musically there wasn't much I planned to see on the second day. Two bands that are pretty new to me but I was looking forward to were Demdike Stare and Yamantaka // Sonic Titan. Both of them were a little bit underwhelming - Demdike Stare is atmospheric and has good video, but not sure it built up to much. Yamantaka were pretty good, especially their song "Queens", and they had some great costumery, with one of the singers looking like some big hair-creature out of a Studio Ghlibli film.

Sunday we had a lovely beef roast, though I cocked up the gravy so we had none. Then music. The Magic Band were a massive disappointment, not a credit to Beefheart's legacy IMHO, just some noodley noodle. However, they were bad enough that we went next door for Olivia Tremor Control who were fantastic. Their mixture of straight indie-pop and "musique concrete"-like sonic experimentation is just brill, neither of the two components losing out to the other.

Sun Ra Arkestra were also great fun, some great jazz ing. A bit more straightforward jazz than I might have expected, but with a notable appearance of a lovely electrical wind instrument, a buzzy little device played really well by the lead sax bloke.

Later on we joined a queue that had already been queueing for an hour to see Jeff Mangum. It was quite a pleasant queue and the ale people were delivering ale, so we didn't mind queueing for another three quarters of an hour (while Jeff played inside) and eventually went in to catch the last three tracks of his set, including "Two-headed boy" for which most of the crowd sang along. Lovely atmosphere in there. Though apparently the real closing event was a secret gig later that night where Jeff plus Elephant 6 crew, Sun Ra Arkestra and assorted others had a big old jam session...

Syndicated 2012-03-12 12:29:03 from Dan Stowell