Light Wall
The Exploratorium in San Francisco have a magnificent Tinkering Studio. It’s a space where educators, artists and engineers collaborate to produce beautiful, thought-provoking, and just plain fun activities and installation pieces.
One of their classics is Light Play, a wall of frosted screens back-lit with weird and wonderful shadows interacting with the light, with colour filter, and with the screens. It’s a tremendous activity, particularly good with younger children and family groups. One aspect we particularly like is the way it fosters a sense of collaboration and contemplation. If you’re working on the arrangement of materials behind the screen, you can’t really see what effect you’re having, since that’s only properly evident from in front of the screen. So you have to work with others, articulate what looks good, and work out how to get that effect again.
The Exploratorium have written up their approach on their own site and at Instructables.
Light Play workshops from the Exploratorium. Images © Exploratorium, used with permission. Thanks, tinkering.exploratorium.edu!
Our version
We loved the idea of Light Play, and our colleagues at the Centre for Life were keen to produce a set for use here in the North-East of England. But while the Exploratorium’s setup is wonderfully dramatic, for our purposes there were some challenges around component availability, ease of construction, and cost.
So we simplified the components considerably. The results aren’t as gorgeous, but they’re still pretty good. The activity has prompted the response and interactions we wanted, so we’re happy.
Here are a few more details about what we – Think Physics and the Centre for Life – built:
Boxes
There’s nothing clever about our boxes; they’re large cardboard boxes with big holes cut in each end. One end is covered (internally) with good-quality tracing paper to form a screen, the other is used for access.
Things we’d do differently next time
- Use smaller boxes. The ones we picked were 465 x 465 x 600mm, and are just a bit unwieldy in use and particularly in storage. I’d go 100mm smaller in each dimension.
- Cut the holes in the sides, not the end. Rectangular apertures are more interesting than square apertures.
- Using the sides of the boxes also means you don’t have the tape holding the boxes together encroaching on the display face of the wall. Oops.
- Absolutely use double-wall boxes. It’s tricky to cut, but the resulting boxes are tough enough to stand up to many uses – we’ve so far done two Maker Faires plus an art gallery installation and a bunch of school workshops. The boxes are looking scrappy, but they’ve at least one more busy weekend in them.
- Curved corners to the cut-outs are a pain to make, but absolutely worth it in the long run. They look more pleasing than square corners.
Lights
The Exploratorium’s lights use single-LED high-output devices, which are lovely but quite costly in the UK. They also require heatsinks.
Instead, we adopted triplets of extra-bright conventional LEDs. Having three individual light sources, even closely-spaced like this, isn’t ideal – they cast rather awkward shadows rather than the crisp outlines a single source would give, and they’re only just bright enough. However, the effect looks better than we’d feared, and the trade-off was worthwhile in our case. We used sets of three high-output LEDs of various colours, ranging from about 8,000 mCd output up to something like 11,500 mCd. Bear in mind that the sorts of cheap LEDs you’ll find in every electronics kit are rated at about 300 mCd. They’re also fairly cheap from suppliers like Kitronik and Hobbytronics.
We mounted the LEDs up on prototyping board, in series with a single current-limiting resistor to suit the specific LEDs, and powered them off 9V cells (so, ~3V each).
Things we’d do differently next time
- The gorillapod-style positionable necks were a pain to make. Literally. We bought cheap mini tripods from Amazon, un-popped all the segments, drilled them out, popped them back together, then threaded wires up the holes. There were blisters.
- In use, we rarely see people position the lights other than by laying the entire unit on its side. So:
- …next time, I’d just use a short length of dowel or plastic tube as an upright, and maybe mount the LEDs on a couple of segments of positionable leg.
- I’d be tempted to make only white light sources, and offer a range of lighting gels for colouring.
- Consider using small lamps like these from Ikea or these from Clas Ohlsen. On balance I’d probably prefer battery-operated lights, as they allow a finished box to be moved into a group wall display, but there’s a lot to be said for an off-the-shelf lighting solution too.
Fancy Lights
We made a small number of these ‘fancy’ lights. They use an Adafruit NeoPixel ‘Jewel’ array of RGB LEDs driven by a 5V Trinket microcontroller (like half an Arduino, and yes that’s a terrible description). Power comes from a single AAA cell via a step-up board which I still think must work via unicorns or something. I mean, how do you make 5V from 1.5V?! Mind-boggling.
When first booted, a small potentiometer controls LED colour. A second (button) input toggles the Trinket into a colour-cycling mode, with the potentiometer then controlling the rate of change of colour.
They can produce delightful effects… but the power drain is such that they last about half an hour, and hence aren’t terribly useful. Also: everybody wants one. Ultimately, we’ve withdrawn them from the workshop because they don’t add enough to make up for their limitations.
They’re still cute, though.
Turntables
To bring a little motion to the boxes, it’s worth having a few motorised components, like turntables. But they need to turn slowly, which is a challenge. Since I’ve never done the Exploratorium’s workshop personally I just assumed they’d made their own, but compiling this page I’ve realised they seem to be using jewellery display turntables, like these or this. Since I didn’t know that, I ended up reverse-engineering something which didn’t exist in the first place. Hmm. Well, I’m proud of our turntables. They turn slowly (about 1rpm) and despite looking pathetically fragile have proven quite robust in use. The old exhibit standby of ‘if it looks fragile, people treat it with care; if it looks solid, they’ll whack the heck out of it’ seems to apply. They do tend to fall apart in transit, but a minute’s ministrations with a glue gun solves that. The core is a geared 3–6V motor, driven off a single 1.5V cell. There’s enough torque to work reasonably well, and undervolting it slows it down even before you get to the gearing. The drive pulley is a short length of plastic tubing with a cardboard end-cap. A slot in the cardboard cap fits tightly on the motor shaft, then hot glue poured into the tubing fixes it well enough. Gaffer tape wrapped around the plastic tube provides enough friction for the edge drive to the turntable itself. Since we hand-cut the turntable discs they vary in diameter somewhat. The pivoted chopstick and elastic band tension spring keep the drive pulley and turntable in contact. The main turntable bearing is a short M10 bolt glued to the frame – ridiculous overkill, but it’s what we had lying around.
Things we’d do differently next time
Close-up of the drive system. Most of our units have an additional chopstick-segment guide stuck to the motor, which rides under the turntable platter and offers some extra support. I didn’t notice it had fallen off this one before taking the photo, because it worked perfectly well without it. Be aware that additional bodging may be required!
Turntables as far as the eye can see!
Effects, outcomes, and miscellaneous notes
This is a beautiful workshop and installation. The impact of the assembled wall and its ever-changing display is mesmerising, and it delights all ages. We’re not surprised that the new Tinkering Space in @Bristol uses a light wall as a prominent feature.
At Maker Faire UK we observe:
- Broad appeal; families are drawn to the activity, but when there’s clear spare capacity pairs or groups of teens and adults will want to be involved.
- Family groups working collaboratively.
- Dwell times of typically 20 minutes, ±10 mins.
- Lots of back-and-forth revisions and adjustments.
- Discussions around aesthetics, properties of light, narratives, mood…
- With about six work tables, we can work with ~400 people/day.
- Many more people notice and watch the finished display, but we’ve not counted those interactions.
- Two lights per box is about right. Many groups will use just one.
Things we perhaps still haven’t nailed are typically around the available choice of materials, and the nuances of facilitation:
- Too many plastic dinosaurs = ‘Lost World’-themed light wall. A constrained choice of pre-made objects and an abundance of raw materials is probably better.
- Few people try moving the light in front of objects (ie. casting reflected light onto the screen). Similarly, shaping the light by using masks close to the source is fairly rare.
- Go back to the top of this page and look again at the rotating gallery of the Exploratorium’s workshop. Notice the amount of patterned acetate they’re using. It produces beautiful effects, but we’ve found it tricky to entice people to give it a chance.
- The turntables are good, but they don’t prompt a particularly wide range of effects. I’d like to motorised widgets which could be fixed to the top of the box and turn things on strings, or could wave things back-and-forth, or … (etc.)
- High-mounted lights + low turntables = all the movement is at the bottom of the box. There are many ways to fix this, but we need to make some of those solutions more obvious.
Wrapping up
We love this activity. Here’s what it looks like in the hands of secondary students:
Technology Wishing Well
Caution
We never really did finish writing up this project before we headed off on our next ridiculous Maker Faire build. And then the one after that was a revamp of this one, renamed ‘Pirograph,’ which – you guessed it – we never really finished writing up either.
One of these years I’ll find time to make a really good version of this project, and will probably write it up as a tutorial for MagPi magazine or something. But I wouldn’t hold your breath. If you’re a final-year student at Northumbria who’d like to explore a project at the intersection of OpenGL, coding instruction/education and computer art… please drop me an email!
Maker Faire is an international network of events celebrating people who make, craft, build and do, using technologies old and new. The movement started in California ten years ago, with the first international Maker Faire starting a couple of years later not merely ‘right here’ in the UK, but right here in Newcastle. Maker Faire UK is a big deal: it’s more than 100 exhibitors and ten thousand visitors gathering at the Centre for Life for two days of show and tell, hands-on experience, performance, and invention.
For last year’s Faire, Think Physics built a family activity – the Light Wall – and a pendulum wave piece which was part instrumented physics demonstration and part musical sculpture.
Our planning for 2016’s Maker Faire UK started even before the last one finished. Both our installations saw a terrific response last year, but we particularly liked the family discussions prompted by the Light Wall. We also enjoyed the technology aspects of the pendulum installation, as the techniques we learned pointed us in some interesting directions with our other work through the year.
So this year, we built… the Technology Wishing Well.
Long-exposure photograph of the Technology Wishing Well installed at Maker Faire UK, 2016. Image: James Brown.
Award–Winning!
We’re proud to say that the Well picked up not one but two ‘Maker of Merit’ blue ribbons from Maker Faire UK, including one from Maker Media VP and co-creator of Maker Faire itself Sherry Huss, who was visiting from San Francisco.
The third ribbon Carol’s proudly displaying here was also from Sherry, for our Light Wall activity (which also picked up a blue ribbon last year). So Think Physics now has two multi-award-winning Maker Faire installations. Yay us!
Wishing Well Gallery
Our pick of some of the best images the Well has produced to date. These pictures build up very gradually – the gallery images took anything from a few minutes to an hour to produce. It’s mesmerising to watch…
What the Well is
A large black turntable disc spins slowly. Above it, a camera takes photographs, and some simple image processing turns all the black parts transparent and adds all the photographs together, displaying the result on a large screen. So far, we have a device which takes photographs of… nothing.
Add a light to the turntable, however, and soon the screen is showing a circle – the path traced by the light as the turntable turns. More lights = more circles.
Add lights mounted on rotating arms, and you get… what, exactly?
The Technology Wishing Well is a device for exploring patterns and the ways rotating objects interact with each other.
How to use the Well
At Maker Faire UK, we invited visitors to make a wish. You need two things to wish at a wishing well: a thing to wish for, and a token to cast into the well. Traditionally the tokens are coins, so for the Technology Wishing Well visitors make illuminated tokens our of coin cell batteries. A battery, LED light, and a twist of black tape, and you’re done.
More challenging is working out your wish. What future technology would you like to see? What are your hopes? Your dreams? Your aspirations? Your concerns, perhaps? Write a note on a card, hold it up to our selfie camera, and the Well tweets your photograph and your wish, along with its own comment.
Then you cast your token into the well, and see how it contributes to the swirling display as it develops.
Make your own Well!
We’re going to write up a proper ‘how to’ guide, based around the tabletop demonstration Well we built. If you’d like to build your own, you’ll need:
- A Raspberry Pi 2 or 3.
- A Raspberry Pi Camera (we haven’t yet tested with the new Camera module v2, but it should be easier to work with and produce better results than the older cameras we used).
- A lazy susan cake turntable. Ikea sell a decent one for £5.50.
- Some black paint or card, to cover your turntable.
- Some way of clamping the camera above your turntable. We used lab retort stands, but you could use an angle poise lamp and some gaffer tape.
- An extension cable for the Pi Camera is helpful, though we didn’t have one for ages and just clamped the Pi itself.
- A motor to turn the turntable is good, though not essential.
- A few LED lights, flat watch batteries, and black tape. Though there’s a lot of fun to be had using things like straws and coloured pens, too.
Problems
The biggest issue with the Well is that it just isn’t very quick: the code draws a few frames per second only, which isn’t as satisfying as we’d hoped. At one point (on a plane to Bangkok, as it happens) I got fairly heavily into Python performance profiling, hoping I’d find a single slow subroutine I could work around. Unfortunately, my conclusion was… er… that Python is a bit slow for this sort of thing.
A couple of years after the Well we rebuilt the system and used a big dual-Xeon workstation to run multiple instances of the algorithm in Processing. That was great in that it allowed us to have eight simultaneous streams going on, but each one ran at only about the same rate as the Python version.
At some point, we’ll curl up with a good tutorial and learn just enough OpenGL to see if we can get the transparency and compositing calculations running on graphics hardware. Because that should look spectacular. But at present rates of progress, we don’t expect this to happen… er… soon.
The Technology of the Well
The list of technology the Well uses surprised us even as we were making it. Partly because it’s a long list, and partly because most of this stuff was reasonably easy to glue together. We’re not great programmers at Think Physics, but with a little perseverance and a lot of Googling we’ve managed to build this wondrous thing. We’re very proud of ourselves, and if we can do this, so can you.
The Well uses:
- A Raspberry Pi (3) and Pi Camera to do all the core image processing. The main application runs in PyGame, using a combination of Pillow and Numpy for image manipulation.
- A second Pi – this time a Pi 2 – to handle the Twitter camera. This Pi also pulls images off the first Pi every so often, to tweet the current state of the Well.
- A third Pi pulls images off the second, displaying a gallery of the wishes of previous visitors. This Pi is as old as they come – an original 256Mb RAM Model B. It’s sloooooow, but it does the job.
- A fourth Pi (maybe a 3? I’m honestly not sure) commands the rotating light robots. It runs the Mosquitto MQTT server for message-passing, and a graphical application written in PyQt.
- The rotating light robots run on Adafruit Huzzah controllers, which are cheap wifi-enabled boards. They’re driving NeoPixel colour-changing LEDs, and are glued to continuous-rotation servos. The package is powered with three AA batteries. We call the robots ‘Skutters’ because they remind us of the robots in the comedy series Red Dwarf. The skutters were built by students from Churchill College Maker Club, which saved us a lot of soldering and fiddling with tiny bits of wire.
- We’ve a wifi hub so we’re self-contained, then we’re routing that network out to the world. We tried really hard to make that router yet another Raspberry Pi, but after a few hours we gave up, plugged a Mac in, and clicked about three buttons. If anyone at the Faire is an ipfw guru we might yet manage to solve this.
- There’s another Pi – another 3 – running a tabletop version of the installation, to demonstrate that all your really need is a Pi, a Pi Camera, and a lazy susan turntable. We bought ours from Ikea for a fiver.
You’ll find all the code we’re running at the project’s Github page. It’s very roughly-presented right now. If you have a Pi Camera it’s really very straightforward to get this stuff running for yourself. We’ve love to see your results, and you might also want to fix some of the bugs and problems with our programs!
Building the Well
The Technology Wishing Well was built mostly by Jonathan Sanderson and Joe Shimwell very gradually over several months (then very frantically over a couple of weeks). We had lots of help from James Brown, and from Miss Brown and the Churchill Community College Maker Club. Here’s what the process looked like:
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Technology Wishing Well
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