QR_STENCILER and QR_HOBO_CODES
5 August 2011 / code, infovis, projectNOTE: This page is an archival copy. The ‘official’ web page for this project is:
http://fffff.at/qr-stenciler-and-qr-hobo-codes/.
Yep, it’s a QR code stencil generator! In cooperation with the F.A.T. Lab and my student Asa Foster III, I am 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.
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.
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.
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