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Fun and games with geodesic domes and LEDs – part 1

 

Last year I built a 5m geodesic dome, covered it in LEDs, and took it along to a festival in the UK called Burning Nest.

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The dome itself was constructed using a connector kit from buildwithhubs.co.uk. It’s a 2v dome, is 5m in diameter and 2.5m high at the apex. Geodesic domes are (typically) icosahedrons which have been subdivided some number of times to more closely approximate a sphere, then cut in half to make up a dome. For 2v (or 4v, 6v etc.) domes you can cut them exactly in half. For 3v etc. domes you have to make the cut off-centre, so they end up being either flatter or taller. This article is a really great overview of the geometry involved.

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The kit comes with hubs and connectors, which in my case combined with a job lot of broomsticks to give the edges and vertices of the dome. All the sticks are lovingly painted with metallic gold paint and varnished to hopefully improve their longevity. The dome packs down to two bundles of sticks (2v domes can be made up entirely of two lengths of stick – 3v typically requires three lengths) around 1.5m and 1.3m long. Putting the dome up takes under half an hour. Rigging the LEDs takes a little longer!

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The LEDs are WS2812 5v individually addressible RGB LED strings. I got a bulk order of them from AliExpress. The dome requires 1760 LEDs (55 edges, 32 LEDs per edge). The LED strings are 64 pixels/LEDs long. The LED system has been designed to be flexible (i.e. it isn’t specific to the dome) and currently has 4 control boxes (each of which is weatherproof, and capable of driving up to 8 channels of 64pixels each – 512 LEDs). Each box has a 150W 240v power supply, a Raspberry Pi v3, and a Fadecandy inside. The Fadecandy takes care of driving the WS2812 LED protocol, and the RasPi runs my custom lighting control software – Magiclights.

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The boxes can be used to drive a variety of LED form-factors, and the software is intended to provide a simple and intuitive interface to easily add lighting to existing or new artistic projects. The interface is built around the concept of using images as a source, and applying algorithms to transform those images into an output display format (for example, taking an image and smoothly fading between lines of pixels in it).

There’s a few videos of various rigs (including the dome) on my YouTube channel.

Recently I’ve been working on improving the system (with a view to returning with it to Nest, and being a lot more relaxed about it). I’ll be writing more about that in the next post, but the key improvements I’m aiming to make are:

  • Change the interface to give realtime feedback of the system’s playback status (to make it more responsive)
  • Add the ability to treat the output as a graph, so that image patterns can be combined with graph-traversal algorithms to produce interesting effects.
  • Also add the ability to model the output pixels as a 2D surface, or 3D shape (which would enable even more interesting effects, like volumetrically rendered visual effects).

On the hardware side, I’d quite like to provide an option to run the entire system off of a 24V DC low-voltage power supply – opening up the possibility of using battery power.