Yep, it’s a QR code stencil generator! The F.A.T. Lab is pleased to present QR_STENCILER, a free, fully-automated utility which converts QR codes into vector-based stencil patterns suitable for laser-cutting. Additionally, we present QR_HOBO_CODES, a series of one hundred QR stencil designs which, covertly marked in urban spaces, may be used to warn people about danger or clue them into good situations. The QR_STENCILER and the QR_HOBO_CODES join the Adjustable Pie Chart Stencil in our suite of homebrew "infoviz graffiti" tools for locative and situated information display.

CONTENTS

ABOUT THIS PROJECT

QR codes are a form of two-dimensional barcode which are widely used to convey URLs and other short texts through camera-based smartphones. A variety of free tools exist to generate QR codes (such as the Google Charts API) and to read them (such as TapMedia’s free QR Reader for iPhone app). Our QR_STENCILER is a Java-based software utility which loads a user-specified QR code image — from which it then generates a lasercutter-ready, topologically correct stencil .PDF. As Fred Trotter 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 (sometimes called contour tracing). QR_STENCILER was created with Processing, a free, cross-platform programming toolkit for the arts.



Closeup of a QR code lasercut in 1/8"-thick fiberboard. The QR_STENCILER automatically thickens corners between squares (left) and generates "bridges" to connect stencil islands (center). The level (amount) of island bridging is user-adjustable.

Accompanying the QR_STENCILER are the QR_HOBO_CODES (see below), 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. We present these as modern equivalents of the chalk-based "hobo signs" 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, that are specific to contemporary conditions ("insecure wifi", "hidden cameras", "vegans beware").



Examples of 19th- and 20th-Century "hobo signs". Sources: Fran DeLorenzo (left), Wikipedia (right).

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.

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. (See this QR code for an example; it has 23-pixel grid-cells in an overall image size of 540x540px.) Download QR_STENCILER.zip, and unzip this to a folder. The QR_STENCILER is also available from this Github repository. 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. Put your QR code image in the folder, ‘QR_STENCILER/data/’ Launch Processing and open ‘QR_STENCILER.pde’ Press ‘Run’ (Command-R) to start the stenciler. You will be prompted to Open your QR code image. (A default “hello world” QR code will be opened if none is provided). After opening the QR code image, the program will generate a stencil .PDF in the ‘data’ folder. Note that there are some options (checkboxes, sliders) which you can use to alter the generated stencils in various ways, including (for example) generating “reverse” (white-on-black) stencils. The .PDF can be opened in your favorite CAD program, for laser-cutting materials like cardboard, delrin, MDF or acrylic. If you need to find a lasercutter, consider Ponoko.com, which ships anywhere. You can also Google ‘lasercutting service‘ to find a bureau near you, or check the Architecture or Design departments of your local university. (Of course, you could always print out the PDF on paper if you prefer to cut the stencil by hand. Cheap!) For non-permanent outdoor marking materials, we recommend Erwin Strait-Line 64908 powdered chalk; black spray chalk; black finger paint; and Crayola Sidewalk Paint. After marking your stencil, test it with a QR code reader, such as TapMedia’s free QR Reader for iPhone app.



More photos: 1, 2, 3, 4, 5.

LICENSE

The QR_STENCILER software is provided "as is", without warranty of any kind. QR_STENCILER is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. You are free to distribute, remix, and modify QR_STENCILER, so long as you share alike and provide attribution to FFFFF.AT. The repackaging of QR_STENCILER as or into commercial software, is expressly prohibited. Please note that QR_STENCILER also enjoys protections under the GRL Repercussions 3.0 license. More details about QR_STENCILER’s license and warranty can be found in the preamble to its main code file, QR_STENCILER.pde; for other uses, please contact us. The 100 QR_HOBO_CODES and their respective stencils are hereby dedicated to the public domain.

QR_HOBO_CODES



25-minute wait

png | stencil

assholes

png | stencil

bad coffee

png | stencil

bad food

png | stencil

bad tempered owner

png | stencil

bad water

png | stencil

be alert

png | stencil

be quiet

png | stencil

be ready to defend yourself

png | stencil

beware pickpockets

png | stencil

bike thieves

png | stencil

boring

png | stencil

broken meter

png | stencil

camera perverts

png | stencil

camp here

png | stencil

cars ticketed

png | stencil

caveat emptor

png | stencil

changing table

png | stencil

cheap drinks

png | stencil

check cashing

png | stencil

civilized place

png | stencil

contraception available

png | stencil

cops active

png | stencil

cops inactive

png | stencil

danger

png | stencil

dangerous homophobes

png | stencil

dangerous neighborhood

png | stencil

dishonest scalpers here

png | stencil

dog

png | stencil

food for work

png | stencil

free doctor

png | stencil

free out-of-date food

png | stencil

free wifi

png | stencil

get out fast

png | stencil

go straight

png | stencil

good cheap food

png | stencil

good coffee

png | stencil

good for a handout

png | stencil

good to kids

png | stencil

good veg-burger

png | stencil

good water

png | stencil

GPS is incorrect

png | stencil

great dumpster

png | stencil

habla espanol

png | stencil

has showers

png | stencil

help if sick

png | stencil

here is the place

png | stencil

hidden cameras

png | stencil

high-fee ATM

png | stencil

hold your tongue

png | stencil

insecure wifi

png | stencil

it’s fake

png | stencil

just ignore him

png | stencil

keep away

png | stencil

keep going

png | stencil

kind family

png | stencil

lax oversight

png | stencil

look down

png | stencil

look up

png | stencil

lots of outlets

png | stencil

mean to children

png | stencil

nice bathroom

png | stencil

no bathrooms

png | stencil

no changing table

png | stencil

no fee ATM

png | stencil

no outlets

png | stencil

no pets

png | stencil

no privacy

png | stencil

open late

png | stencil

over-priced

png | stencil

over-rated

png | stencil

owner gives to GOP

png | stencil

owner has a gun

png | stencil

perverts

png | stencil

pissoir

png | stencil

Plan B sold here

png | stencil

prostitution sting

png | stencil

scammers

png | stencil

sleep in barn

png | stencil

speed trap

png | stencil

stay low

png | stencil

strong phone signal

png | stencil

talk religion

get food

png | stencil

tell a hard luck

story here

png | stencil

test market

png | stencil

those aren’t real

png | stencil

toll road

png | stencil

tramp camp

png | stencil

tramps arrested on sight

png | stencil

turn left here

png | stencil

turn right here

png | stencil

unexpectedly good coffee

png | stencil

unsafe area

png | stencil

use gloves

png | stencil

used frying oil available

png | stencil

vegans beware

png | stencil

well guarded

png | stencil

will give to get

rid of you

png | stencil

work available

png | stencil

worth saving

png | stencil

ACKNOWLEDGMENTS

QR_STENCILER was created by Golan Levin and Asa Foster III with support from the STUDIO for Creative Inquiry at Carnegie Mellon University. Thanks to Ben Fry, Andreas Schlegel, Marcus Beausang, Neil Brown & Judy Robertson for the terrific code they have made available online. A tip of the hat to Fred Trotter, Jovino, Ric Johnson, le Suedois, Patrick Donnelly, David J. Burden, Matt Jones and others who have gone down similar or related paths. Additional thanks to Andrea Boykowycz for creative input. Some of the QR_HOBO_CODES are adapted from or inspired by designs presented elsewhere by Fran DeLorenzo and Cockeyed.com. "QR code" is trademarked by Denso Wave, Inc.

KEYWORDS

Barcode, QR code, stencil, QR code stencil, graffiti, grafitti, graffiti research, graf technology, street art, culture jamming, tactical media, urban messaging, locative media, situated visualization, contextual computing, lasercut, laser cutter, digital fabrication, template, chalk signs, chalk, spray paint, spraypaint, fffffat lab, hobo culture, hobo signs, warchalking.