I love QR codes.
I think the notion of simple graphical URLs is beautiful and elegant. If my wife were a graphical data object, I think she would be a 2D QR code.
Think of it, you can put links anywhere you want, in the real world!
You can put them on tshirts, coffee mugs, stickers, business cards… anything in the real world becomes a link to something in the virtual world. Awesome.
I have been playing with QR codes, with an eye towards gamification and behavior change for quite some time. I love the fact that with android and/or iphones you can rely on the GPS coordinates that webkit (the core of both browsers) will provide, makes a QR code a token that can do different things in different places. Think of the possibilities!
You could make geo-caching much much more interesting…
But how do you make durable (or intentionally not durable) QR code in a reproducible way? How do you manufacture large QR codes, that can be scanned accurately at a distance?
The first approach is simple to print the QR codes on either single sheets (A4 or US letter) and then clear paste them to some type of flat surface. You can use throw-away planks of wood from the hardware store to make durable QR code links. But what if you want to make a QR code on some permanent surface, like a wall or pavement. This basic idea can be taken pretty far, for instance you can paste the printed QR codes into ceramic tile or even bake it on, for a near permanent tag.
The simplest solution would be to use a stencil with black spray paint. QR code scanners vary greatly in their ability to pick up contrast, but the color black, and some other color, will almost always pick up. This has an advantage over gluing paper, because you can tag objects that are not entirely smooth. Moreover, with spray paint that does not damage the surface (more later) you can create images that can be placed out in public, non-destructively.
But what is the problem with a QR code stencil? In a word, islands. In order to make a stencil with, say, photo paper (which would otherwise be a great technique), you need a way to address bits that the stencil needs to block, that are not physically connected to the rest of the stencil. Its easier to show than explain. If you are spray painting black, for instance, and you want to make a stencil of the following QR code, you will have the following trouble spots:
See the issue, the two anything white, that does not connect to something else white (even by a corner) is going to be an issue. You might be able to make something clever for the places where this happens in most/all QR codes, but each QR code is going to have random “islands” that are often just one pixel big… and in different spots each time. These are the real headache. Making a traditional stencil simply will not work.
Also, making a stencil is very very slow. If you have to cut each pattern by hand.. ouch… way to much time. We need something faster too!
My first approach to solving this problem was to try and find a programmatic solution. For a given URL, there are many different ways to encode into a QR code. It might be possible to use an algorithm that detects this type of “island status” to find a QR code solution that did not happen to have any islands. You could make an application smarter by posting meaningless GET variables at the end of a URL until you found a version of the URL that would work (of course, I am focused on using URL shorteners like bit.ly to ensure that you have a simple-as-possible QR-code. The more character in the URL, and the more complex the QR code is and the harder it is to make a stencil. The shortener ensures that the QR code is manageable.
I gave up on this technique after noting that there were islands in all of my test runs for various URLs, but the idea is sound.