More Dublin Street Art

I took another walk around the streets this morning. The light and atmosphere wasn’t quite as idyllic as it was a couple of weeks ago but the old city was looking all right, and the James Joyce bridge was in a reasonably photogenic mood.

I went off into the side streets this time, looking for some more street art, found quite a bit as there is some sort of effort going on at the moment to add a bit of life and colour to the place.

First stop was just up by the Liberties

And then back around by the NCAD – clearly someone is channelling their inner Banksy with the first one here.

And then I ended up around the Grafton St area, not much to see there but this advert for Phantom FM was quite cool.

And then back down towards the Liffey, taking in the Andrew’s Lane Theatre, and something in Temple Bar that might be a shop front or might be graffiti and I can’t tell for sure but it was worth taking a picture of .

Once over the river I decided to follow the Luas tracks for a bit and found some pretty cool stuff

Fegan’s Cash and Carry was a magnet for some great work – I really like these two.

But this one was awesome:

And then on to Coke Lane by Smithfield – the Cinnamon Cafe’s security shutters were nicely done and this dead space with its old walls and ramshackle looked quite surreal with the weird light reflecting in from all the glass around that part of Smithfield

But then I turned a bit to the right and found this, that just blew me away. It was a really nice way to finish off the walk around the city centre too.

What makes it even more special to me is that I have no idea who CB is and, despite the presence of that @ourtimeourcity Twitter handle, the words in this poem do not register any hits on any search engine. Not yet anyway. It’s just stuck to a lamp post, adding something amazing to the city, something real.

Walking around Dublin on a calm winter’s morning.

I was walking around Dublin this morning and got some pretty good shots of the Liffey looking like a pane of glass.

I also noticed a lot of Graffiti\street art that I don’t remember seeing before:

Bondi Beach Club, a bit off to the left of the above picture.

And some interesting stuff near Grand Canal Dock:

 

Grand Canal Dock itself is looking very nice these days.

 

And then I came across this very nice piece near O’Connell Bridge. I’ve passed this quite a few times without noticing it.

And finally two slightly weird ones. On the left is the gable end of “The British and Irish Shipping Company” building near Sir John Rogerson’s Quay. And no, the building does not have a rose window, that’s either graffiti or something left over from a film set. It’s definitely a drawing\poster, not real and very odd. 

On the right is a really weird piece of something mechanical embedded in the pavement in front of part of the Irish School of Art ( I think). It looks like a cross section of some form of cylinder head from an engine but the markings on the right list off metres and feet. Very cool looking though. It’s about 40cm or so in diameter if you want to get an idea of scale.

  

Keepy Uppy hack at Science Hack Day Dublin

Loads of fun, more posts to follow but some pictures for a start.

And all of this gives us data like this ( dropping a ball and then a kick, followed by freefall followed by another kick and freefall pair of events:


Freefall   G:     72 Duration 0.00238265 Launch Delay 2.64402304
FreeFall End

Launch G:    313 Duration 0.00305754
Launch End

Freefall   G:     70 Duration 0.02869233 Launch Delay 0.37855668
FreeFall End

Launch G:    445 Duration 0.04812543
Launch End
Freefall   G:     26 Duration 0.37386897 Launch Delay 0.06773423

More adventures with Raspberry Pi and an IMU

Buying a cheap IMU is definitely a good way to learn about working with sensors. When I last posted about this I'd managed to get some sensible data out of 3/4 of the sensors but hadn't realised all the fun I had ahead of me.

Right now I think I'm about 25% of the way through getting to a stage where I'll be confident about working with this thing but at least I'm now getting good data from all of the components and my Raspberry Pi can tell me this sort of information with a refresh rate of around 100hz:

Accelerometer xyz  g: 0.008,0.023,1.005                                         

Gyroscope xyz    dps: -0.061,0.166,-0.674                                       

Mag xyz        gauss: 0.002,0.055,-0.074                                        

Bearing          deg: 2.045                                                     

Gyro Temp      deg C: 28.000                                                    

Temp           deg C: 25.900                                                    

Pressure      Pascal: 99334.000                                                 

Bar Alt  m (sea lvl): 167.353

That might not look like much but getting this far has involved a lot of work with documents like this beauty, from Freescale.

I'm not finished with the Compass\Magnetometer yet, the bearing data I'm getting right now is only roughly calibrated and not tilt compensated but I now know what I need to do to get that properly corrected. The Gyro Temp sensor doesn't work but that's not a big deal, the barometric sensor gives me a good temperature reading.

The next challenge is getting these properly calibrated and establishing how accurate\noisy the particular components are. The compass and gyro are the big headaches on this front, the gyro because it is inherently a noisy signal and the compass because I need to actually code solid routines for handling both hard iron interference ( ie magnetic interference fixed with respect to the reference frame of the sensor ) and soft iron interference ( magnetic interference that varies with position ).

After a couple of days failing to understand the sensor data I had thought the compass ( a Honeywell HMC5883L ) was broken. When I thought I should be getting numbers that would vary between +-(something) in each axis as I rotated the sensor I was getting something very different:

Bearing	X	Y	Z
0	-683	-473	-442
45	-773	-420	-436
90	-800	-311	-433
135	-749	-222	-436
180	-647	-194	-441
225	-561	-258	-447
270	-545	-354	-451
315	-589	-436	-449
360	-683	-472	-442

I blame the amount of time I have to work with PowerPoint for the fact that I couldn't see a pattern in that. In any case I thought I should simply be able to apply a tilt transform to make this better but that actually made things a lot worse. I really should have read the Freescale white paper earlier.

Anyway I got led on a number of wild goose chases as a lot of people seem to have issues with this sensor but none of the code that I found helped. I even tried switching over to an Arduino and testing code from a number of sources for that. The code worked, the values still didn't.

The light bulb moment came from a comment on a blog post about the HMC5883(L) from a guy called Cory who worked on a similar IMU that gave me the clue I needed to solve the problem. The comment wasn't actually about the IMU that I have but he said that the BMP085 pressure sensor they used was actually magnetic to some degree and my IMU also uses that pressure sensor. That meant that that there was probably a fairly significant hard iron interference issue on my little board and a quick graph of the above sample data showed me a smoking gun. Ideally, on a calibrated compass with no interference, the data below would have been a circle around the origin but the fact that what I was seeing was vaguely circular was enough to tell me that it was working and all I needed to do was to sort out the interference problem if I wanted it to be useful.

The really important lesson in this is it is always worth trying something visual if you are trying to make sense of data. I think that needs to go into The Rules, preferably with a number somewhere high up the list, just after the bit where you actually pay attention to things like calibration and sources of interference.

A slightly larger data set has given me a baseline transform for the hard iron interference - this is simply an x,y,z offset so it's only trivial code and while it is not as accurate as I want to get to it's more than enough to tell me that the sensor is working correctly. It now reliably indicates that North, East, South, and West are approximately 90deg apart at any rate.

All code is up on Bitbucket ( I seem to be having some sync issues with this right now, that should be sorted out shortly Fixed..).

Raspberry PI - Interfacing with an IMU

I picked up a dirt cheap I2C capable 10-DOF "IMU" breakout board with from e-bay ( this one here ) just to see how hard it would be to get some motion sensing capability for my Raspberry Pi. I know that we've had all these sensors built into phones for years now but it's still amazing that I can now buy a 3-DOF Accelerometer, 3-DOF Gyro, 3-DOF Digital compass and have a temperature\barometric pressure sensor thrown in for €20. 

After a bit of minor soldering a quick test proved that all the parts were visible over the I2C bus but I could only find Python libraries for the pressure sensor. This was not a surprise, and frankly I wanted to have to work a bit to get sensible data and I really wanted to have a project that I could use to learn Python. 

The breakout board has these sensors:

• Gyroscope L3G4200D Datasheet
• Accelerometer ADXL345 Datasheet
• Digital Compass HMC583L Datasheet
• Temperature\Pressure BMP085 Datasheet

The extremely useful AdaFruit Learning System has a basic tutorial, complete with a working interface library for the BMP085. I already had one of those working ( it's on a second Pi that I bought because my first one was taking so long, so now it's monitoring the temperature and pressure in my attic - you can see that data here: https://cosm.com/feeds/80617 ) . That sample gives me enough of a framework to try building up the necessary libraries for the other three sensors. 

I've had a couple of evenings to hack away at this and I've now got sensible, if uncalibrated, data from both the accelerometer and magnetometor via Python. AdaFruit's Raspberry Pi WebIDE has been a joy to use for this sort of learning exercise - it's clean and simple (which I need right now) and its integration with Bitbucket means I can easily point people at the code I've managed to hack together so far:

• ADXL345.py
• HMC5883L.py

This stuff just about works and I'm sure anyone who has any sort of Python skills will find a ton of newbie errors and bad practices in there but hey, they work and I will be cleaning them all up as I learn how to do all this properly. And hopefully I'll have the L3G4200D Gyro in there over the next couple of days. 

Interesting Times

I’ve been thinking a bit about the fact that we’re living in a time of monumental change that is running rings around the established systems of the world.

First consider that the world we live in now is one where the average computing power, and digital storage available to individuals is increasing at a rate that is roughly equivalent to a 64x improvement in performance, capacity or cost-effectiveness over the lifetime of an average political leader ( 8 years ). Those in nominal control of things haven’t got the beginnings of a clue what that actually means, they are struggling to come to terms with the concept that stuff that was functionally impossible a handful of years ago is easily managed by a school-kid with a phone today. And the idea that such school kids might actually have experience with the complex multi-tasking needed to marshal armies is something that I suspect rarely bothers them but it probably should, after all hundreds of millions of hours are spent by the youth of today doing just that, only they call it online gaming.

Have a read of Ben Hammersley’s awesome speech last month to the IAAC. He puts forward some ideas there that are well worth reading at any point in time but it is truly worrying to think about the conceptual problem the rulers of the world have given the things that are happening right now.

So there are clear problems with “The Suits” trying to get their collective heads around security and governance in a world that changes faster than they can change their ties and pin stripes but so far they have mostly only been dealing with the effects of revolutions in communications capabilities and patterns. Now even those can be dramatic – the Arab Spring and the London Riots both showed how social networks and cell phones can pose existential threats to governments. It is interesting to note that these are proven existential threats, unlike the fake existential threats that Hammersley talks about that have prompted the ridiculous security theatre of Airports and the rest of the pointless moves towards a ubiquitous surveillance society.

Now think about the following two articles I read today about some interesting legal edge cases in the world of 3D printing.

3D Printed parts for Automatic Weapons.

ATM Skimmer Gang invests in 3D printer.

Once the ability to print your own guns, and any other illegal machinery of your choice, gets out there it will be out there and no amount of banning will put that genie back in the bottle.

Interesting Times doesn’t even begin to describe what I suspect is about to happen.

I think that despite my previous rant about being able to buy Rule-34 as an e-book that I really should go out and get a copy.

What the austerity plan actual means to you and me.

So we now have some fairly solid information about what the next three to four years worth of budgets are going to look like.

It’s pretty fucking savage: To put it in easy to understand terms, take 60% of your current gross salary - that’s effectively what you will be earning in 2014 in todays terms.

Now I know that this is what is needed in order for this particular plan to succeed but I don’t think the average sod on the street understands precisely what that means for the amount of money they will have left if it does actually work.

Oh and that’s before we even begin to consider paying for the banks. This part is just about getting our current budget balanced.

There are actually some long overdue and good ideas for reform in the plan too, but I don’t think there will be anyone worthwhile left in the country by 2014 for them to matter.

 

The Numbers, for those who are interested.

Income Taxes: The plan outlines €1.5bn in tax increases from additional individual direct taxation ( ie you pay more tax, get lower tax credits or pay some new taxes ). Since there are about 2.2million individual tax payers in the country tat will average out at an extra €700 per annum. given the income distribution of those earners the _average_ PAYE tax payer will be paying around €1000 more in direct taxes next year. 

Spending Cuts: Then there will be €2.1 billion in spending cuts. A significant chunk of that will hit the less well off via social welfare cuts, and a nice chunk should be realised by trimming down the civil service numbers but at least €500m or so will come from reductions in general “benefits” – many things that are now free, or subsidized will have to be paid for adding up to another €250 or so per taxpayer. That’s money you have today that you wont have this time next year.

Where we have to get to: Now remember that we are €18bn or so out of balance and need to bring that down to about €15bn to hit the deficit target. This first step addresses €3.6bn of that. So by the start of 2014 every tax payer in the country will take home (on average) €4000 or so less than they do today on the same earnings. Those that earn around the average wages for the country will end up with about €5000 less net take home pay per annum.

Net Income per person: To put that in context someone on the average income in Ireland today (€35k) who will take home about €28k (after PAYE, USC, PRSI and the rest). Or in other words they will pay about €7k in tax. By 2014 the plan is that they will pay €12k in tax – an increase of about 71% in the individual direct tax burden.

Inflation: Meanwhile we have high double digit increases in Medical Insurance (20%+ so far), Electricity (Bord Gais 12%), Gas (Bord Gais again 22%), Petrol is up about 15% over the past 12 months and there is no sign that it will abate. These increases will continue and on average we will all pay about €1500 per annum more for these core necessities each year. Even if the now freeze those costs we are all going to be €1500 worse off per annum next year based on the increases that have already been confirmed.

Mortgages: A 20 year mortgage for the average house price as it was in 2008 ie €300k , calculated on a monthly repayment basis, at 4% costs €1812 per month. If the rate rises to 6% that increases to €2138 per month. The increase is €3920 per annum. The actual average outstanding mortgage is probably only €200k but even at that level your average punter will end up €2700 worse off.

Putting it all together: An average PAYE earner on €35k gross who has €28k to live on today will find that in three years they have the same buying power at that point in time that someone who earns €21.5k gross has today (about €19k net).