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Art: Eggbot Drawbot... in Colour
24th June 2012

I've been working on a drawbot based on Eggbot and Sandy Noble's Polargraph for probably a year or so, if not more. I've finally cracked the accuracy problems that have plagued it for most of that time and the point where it became useful coincided with StippleGen being released by Evil Mad Scientist, able to produce beautiful stipple patterns for Eggbot and other plotters.

I've adapted some Processing code to run the stipple patterns StippleGen produces on the drawbot and today I tried a new trick - colour!

I wondered if running StippleGen on the CMYK channels of an image one-by-one might produce a colour image if I plotted them on top of each other.  Initial experiments seemed to indicate that it was promising:

colour drawbot test

I separated the cyan, magenta, yellow and black (key) channels and saved them as PNG for StippleGen to use as input.  I ran StippleGen to generate the stipple pattern and saved it as SVG after optimising the path to save plotting time.  A screen capture of the StippleGen pattern for each of the channels, converted into grayscale then merged into the CYMK channels in a new image showed the result above.

I found a set of felt pens that seemed to give a reasonable set of the four colours needed and ran the stipples one after another.  I had to pay attention to the paper - over-drawing four times could overwhelm paper that wasn't set up for it so I found a pad of Daler-Rowney Bristol Board, made for technical pens and airbrushes. Glossy inkjet paper would probably work also.

The Processing code I use makes filled circles with a spiral pattern that's reasonably quick to draw and I spent a while optimising the servo pen lift/drop speed - 4 channels with 2000 stipples each is 8000 dots, easily the largest plot I've yet done, end-to-end it took about 5 hours with each plot taking over an hour.

Here's the result:

colour drawbot test

The picture above didn't come out that well from my camera but I'm quite pleased with it in person, lots of kudos should go to EMSL for StippleGen - it has rapidly become one of my favourite Processing sketches.

fastness - Iain Banks Graphics
Fastness - Iain Banks Graphics
All of the content from my Iain M Banks website, now shifted to be a section in this one

fastness - Links & Resources:
An open source programming tool aimed at artists, engineers and designers.  Simple, light and Java-based with a wealth of libraries and a strong user community

3D printing for the masses - plastics and metal to your design or team up with a desigenr to personalise a design with a 'co-creator'.  Visit my Shapeways shop for some things I've designed.

MeshLab is an open source, portable, and extensible system for the processing and editing of unstructured 3D triangular meshes

Blender is the free open source 3D content creation suite, available for all major operating systems under the GNU General Public License

GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages

An Open Source vector graphics editor, with capabilities similar to Illustrator, CorelDraw, or Xara X, using the W3C standard Scalable Vector Graphics (SVG) file format

Retail laser cutting outlet with centres in New Zealand, USA, Germany, Italy and the UK (if not more by now)

Java development environment