Iceplate

The first prototype

The required theory was in in order, and we went on a minor field trip to buy the different components needed to build the first prototype. The shopping list included a transparent plate, some semitransparent paper and a mirror, and Silvan seemed as the obvious provider of these items, so off we went.

The purpose of the plate should be supporting the paper, and make the surface pressable by the user. Therefore we sought a fully transparent plate that would not interfere with the light projected from underneath. Since the budget couldn't support buying a special cut glass plate, we bought an acrylic plate instead. It was equally transparent, but less expensive, so it seemed like a fair deal for testing purposes.

Next on the list were the semitransparent paper, but since Silvan really couldn't offer many useful solutions, we decided to see what a typical convenient store could offer.
In Føtex we found that normal baking paper could be a cheap and easy solution, and since they also had cheap mirrors in store, we bought both items and went home to set up our first, quite limited prototype.

Back in the group room a piece of cardboard and some tape became our first mirror stand, and we placed the acrylic plate across two tables with the baking paper on top. We connected the projector and the camera to a computer, and just like that we had our first working prototype.

At first glance it worked excactly as expected, and the image projected onto the paper looked quite good. At second glance there were some problems though.
First of all there were some minor problems with the mirror and the ”screen”. The mirror stand was quite unstable, and even minor movements would result in shaking of the image, or a total movement of the projection.
The acrylic plate turned out to be either too thin or too weak, which resulted in a bendy surface. This issue messed up the baking paper a little bit, which then resulted in an uneven image.
The paper also had too much structure, so the image was corrupted by slightly visible patterns in the paper.

Beside the issues mentioned above, we had an even more annoying issue with the mirror. Along the top and bottom edges of the projected image there were a greenish edge with a height of approximately 5 mm. We tried correcting the angle between the projector and the mirror, in order to see if that could be the issue. We also tried to play around with the settings in the projector software, but none of these possible solutions solved the issue.
Since nothing seemed to solve our problem, we decided to research the issue, and it turned out simply to be a problem with the type of mirror we were using.
The reflecting part of the mirror was covered by a thick piece of glass, and the image from the projector was therefore reflected twice, once at the glass surface, and once at the reflecting material.
This was of course a problem that we couldn't solve by setup, and we started searching for proper alternatives.

We sought inspiration from a former project, ConDio, and the group behind that project suggested to minimize the angle between projector and mirror in order to get the thinnest green edge possible. They also pointed to first surface mirrors as a possible solution. A little research revealed that a first surface mirror, as the name might imply, reflects at the surface of the mirror, and no ghost reflections would then appear. These types of mirrors are less resistant to scratches than normal mirrors, since there is no glass to protect the surface, so we concluded that a first surface mirror was quality over usage, since we wouldn't be able to clean it as normal.

The ConDio group also told us that they had used architechtonic paper for their project, and that this kind of paper had way less structure than baking paper. The paper should be quite expensive, but worth every penny, so we started considering whether to upgrade our equipment or not.
We decided to try another kind of paper that closely resembled the architechtonic paper, and we also borrowed another type of mirror with a thinner glass plate.

With this new equipment in stock, it was time to move on to the next step of our testing phase.

posted by Milla @ 11:20