Monthly Archives: May 2015

Coding with knots: Inca Quipu

This week I’m teaching at IMM Düsseldorf with Julian Rohrhuber which has given me a chance to follow up a bit on Inca Quipu coding with knots, a dangling thread from the weavecoding project. Quipu are how the Incas organised their society, as they had no written texts or money – things like exchanges (for example from their extensive store houses) were recorded via knots. Researchers have been able to decode the basic numeric system they used, but 20% of the quipu seem to follow a different set of rules, along with extra information encoded via thread material, twist direction, colour and other knot differences. I’ve written a python program for converting the Khipu Database Project excel charts into graphviz files for visualising:

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The knots are described in ascii art, with S and Z relating to the ply and knot ‘handedness’ direction they are tied in:

O : a single knot 
O/O : two single knots tied in S direction (it's rotated 90 degrees :)
(\\\\) : a long knot of value '4' tied in the Z direction
/8 : end (figure of 8) knot tied S direction

The pendant nodes also have labels describing their ply direction and the side the attach on, so “S R” is S ply & recto attached.

The hardest part of this has been a bit of more recent media archeology to figure out the colour values, I’ve had to cross reference the original Ascher-Ascher Quipu Databooks published in 1978 which contain their own colour system which more or less maps to the NBS-ISCC Munsell colour chart originally proposed in 1898. Luckily that site provides hex colour values – hopefully they are vaguely accurate, the current lookup table is here:

colour_lookup = {
    "W": "#777777",
    "SR":  "#BF2233",
    "MB" : "#673923",
    "GG" : "#575E4E",
    "KB" : "#35170C",
    "AB" : "#A86540",
    "HB" : "#5A3D30",
    "RL" : "#AA6651",
    "BG" : "#4A545C",
    "PG" : "#8D917A",
    "B" : "#7D512D",
    "0B" : "#64400F",
    "RM" : "#AB343A",
    "PR" : "#490005",
    "FR" : "#7F180D",
    "DB" : "#4D220E",
    "YB" : "#BB8B54",
    "MG" : "#817066",
    "GA" : "#503D33"
}

Weavecoding Munich

Ellen’s exhibition in Munich was always going to be a pivotal event in the weavecoding project – one of the first opportunities to expose our work to a large audience. The Museum of casts of classical sculptures was the perfect context for the mythical aspects of weaving, overlooked by Penelope and friends with her subversive woven/unwoven work, we could explore the connections between livecoding and weaving.

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Practically we focused on developing the tangible weavecoding exhibit for events later in the week, as well as discussing the many languages we have developed so far for different looms and weaving techniques. One of our discoveries is that none of the models or languages we have created seem sufficient in themselves – weaving could be far too big to be able to be described or solved from a single perspective. We’ve tried approaches describing weave structures from the actions of the weaver, setup of the loom and structure of the fabric – perhaps the most promising is to explor the story of weaving from the perspective of the thread itself.

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One of the distinctive things about weaving in antiquity is how multiple technologies were combined to form a single piece of fabric, weaving in different directions, weft becoming warp, use of tablets vs warp weighted weaving. To explain this via the path of a single conceptual thread crossing through itself may make this possible to describe in a more flexible, declarative and abstracted manner than having to explain each method separately as if in it’s own world.

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The pattern matrix has now been made into good shape for explaining the relationship between colour and structure in pattern formation. For the first time we also used all 4 sensors per block on the bottom row which meant we could use a special “colour” block that the system recognises from the normal warp/weft ones and use it’s rotation to choose between 8 preset colour settings. This was quite a breakthrough as it had all been theoretical before.

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Adding this more complex use of the magnetic patterns meant that Alex could set up the matrix as a tangible interface for his tidal livecoding software meaning Ellen could join us for a collaborative slub weavecoding performance on the Saturday evening. The prospect of performing together was something we have talked about since the very beginning of the project, so it was great to finally reach this point. The reverb in the museum was vast, meaning that we had to play the space a lot, and provide ‘music for looking at sculptures by’:

Tangible programming: detecting flip, rotation and id with magnets

When we started designing the pattern matrix we wanted to include the possibility of encoding more than binary (which side is up) using the magnets. In order to test this, we made the bottom row of sensors with 4 in a square – the rest only have one sensor currently (to avoid blowing the budget on hall effect sensors).

Here are some test blocks with four magnets glued on. The one at the back is easy to make as they naturally snap together edge to edge in this pattern, the closer one required superglue and lots of patience – I’m still expecting it to fire a magnet off unexpectedly at some point:

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The orientation seems to work well in our tests so far, as you rotate the blocks the sensors latch from one state to the other – and it seems like they stick to their previous reading until the block is very nearly aligned straight. I’ve added some sound on the Pi to give some haptic feedback which is turning out to be very useful.

The next job was to head back to makernow make some better blocks with the magnets inside. Oliver Hatfield milled out new holes in some of our spares:

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Luckily the fit is really tight so with some force the magnets can be placed inside without the need for any gluing – and they don’t rattle around at all:

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The next thing was to make some visual indication of the polarity and meaning of the patterns, and show how the binary encoding changes with flipping and rotating. Andy Smith designed and laser engraved these new caps and locating rings:

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The 4 bit binary codes read in clockwise order from the top left (same as the notation for tablet weaving) so rotation causes the same effect as bitwise rotate in programming – multiply/divide by 2 with overflow. There are 4 possible different configurations of magnets (which can provide block identification). Two of the configurations are mirrored on both sides but you can read rotation still, with the other two you also can tell which side is up, and one – bottom left in the photo below, can represent 8 states all by itself (flip as well as rotate).

In future we’ll make more of these with specific meanings dependant on the language we use them for and what they actually do – at this point they are for debugging/experimenting further.

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Ellen Harlizius-Klück – Textile MATRIX

Next week the weaving codes project assembles in the Museum für Abgüsse Klassischer Bildwerke in Munich. We’ll be working for a few days surrounded by these characters to get us in a classical mood:

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The museum is hosting Ellen’s ‘Textile Matrix’ exhibition, a crossbreeding of logical science, religion, crafts and visual arts. The word ‘matrix’ originates from the latin word for mother or uterus, but today is predominantly used in mathematics, science and technology. Her work, as much of the weavingcodes project, provides new perspectives on connections between modern digital technology and ancient weaving.

Alex, Ellen, Emma and I will be in residency in the museum from the 6th May and I’ll be reporting our activities here as usual. On the 9th there will be talks and slub will be performing a special livecoding gig. On the 10th we will be presenting the work we have been doing during the residency and inviting people to participate in a citizen science event, exploring mathematics, weaving, music and code – including the brand new pattern matrix tangible weavecoding device.