Slippery circles: Vuforia, Tee Shirts, and computers being picky.

Recently, I was tasked with producing a graphic for a shirt that would be visible with Vuforia, and have an augmented reality game overlayed on top of it. This is all fine and good, except the logo that I made for my company earlier looks like this.

Glimmer Technologies in some of its splendor. So this image tracks well when evaluated by the Vuforia algorithm. From one to five, it's a four. It does this by making a greyscale image and finding unique contrast points in the image like so.

Now, this presents some issues for a teeshirt. We were getting these shirts screen printed which means they have to lay down one color at a time. Moreover, screens cannot print in a gradient, unless that gradient is produced in halftones.

This is a crappy quality image of the awesome work that Threadbare did printing our logo. They had to send our logo to a guy to make a color separation, which then could be fed into their machines which can make halftoned screens of each color. Unfortunately, because of the nature of screen printing, you have to print one color at a time, one over the next. The stacking of these lighter colors in the top right, much of the contrast was being lost. This design tracked at a three out of five in this photo. So I thought I could manually halftone the image and eliminate the issues with the color overlap.

I produced this design to try and convert our gradients into a more printable configuration. In Inkscape, I took my original design and used the tiled clone tool to make one set of dots of varying size for the blue, and one one for the purple in the image. I took these sets of dots and ever so slightly shifted them so that they formed a diagonal grid, so the blue and purple halftones occupied the other's negative space. Super cool I thought. Only two colors I thought. Easy to print, super great. I thought.

The problem is that image cant be tracked for crap. my half-toning process reduced everything into much larger circles than there were before. This means that the image is effectively very blurry to a low quality (cell phone (our target platform)) camera. In addition, it is very hard to make unique contrast points on a field of circles. they are all circular! Every time the computer sees a circle, it could be confusing it with the one next to it. Or confusing that larger circle for that slightly smaller circle. How does it know if the circle you are looking at, is not, in fact, a larger circle that is further away from the camera! This design tracked at zero of five stars.

Once again.

So we have gradients in our logo, which can be made into gradients in a silk-screened design, but in that process, do not track well. Because of this, and how the dwindling timescale was forcing our hand, I made a new design with a new technique.

All of the visual noise in this design was made by taking an existing texture and cutting it into our logo. This leads to a bunch of grippy texture that VuForia can hang on to, and it looks pretty cool. 

Had I more CPU and time, I would create custom shapes to halftone. For instance, some interlocking hexagons! With different wedges missing, and at different rotations they would produce a field of unique contrast points perfect for computer vision. Not sure if the printer, or the camera coudld get that small. Further experimentation is required.