The F.A.T. Manual
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QR_STENCILER and QR_HOBO_CODES Trotter [1] has pointed out, QR codes contain stencil islands in unpredictable configurations. QR_STENCILER automatically detects and bridges these islands, using thin lines that are minimally disruptive to the highly robust QR algorithm. It does so through the use of two basic image processing techniques: connected component labeling (sometimes called blob detection) and 8-connected chain coding (someties called contour tracing). QR_STENCILER was created with Processing, a free, crossplatform programming toolkit for the arts. Accompanying the QR_STENCILER are the QR_HOBO_CODES, a set of 100 lasercutter-ready QR stencil designs created with the QR_STENCILER software. These stencils can be understood as a covert markup scheme for urban spaces — providing directions, information, and warnings to digital nomads and other indigenterati. [2] We present these as modern equivalents of the chalk-based "hobo signs" [3] developed by 19th century vagabonds and migratory workers to cope with the difficulty of nomadic life. Indeed, our set of QR stencils port a number of classic hobo annotations to the QR format (“turn right here”, “dangerous dog”, “food for work”) as well as some new ones, with a nod to warchalking, [4] that are specific to contemporary conditions (“insecure wifi”, “hidden cameras”, “vegans beware”). Download & Instructions QR_STENCILER has been tested in MacOSX 10.6.8, but (since Processing is a cross-platform toolkit) it should work in Windows or Linux as well. 1. Make yourself a QR code image which embeds a short piece of text. GoQR.me, Google and Kaywa all provide free online QR generators. To reduce the complexity of the stencil, we recommend generating your code with the shortest possible texts, and with lower levels of error correction (L-level or M-level). At the same time, we recommend generating QR code images with more pixel resolution, such as 500x500px; for QR_STENCILER, the ideal input image has a “grid size” of about 20 image-pixels per QR grid-cell. 2. Download QR_STENCILER.zip <http://fffff.at/files/2011/07/QR_STENCILER.zip>, and unzip this to a folder. 3. Although the zip includes compiled executables for Mac, Windows and Linux, we recommend running the QR_STENCILER from the Processing development environment. Download and install the Processing development tool. The QR_STENCILER works with Processing v.1.5.1 or later. 4. Put your QR code image in the folder, ‘QR_STENCILER/data/’ 5. Launch Processing and open ‘QR_STENCILER.pde’ 6. Press ‘Run’ (Command-R) to start the stenciler.