Even though the prices of projectors have dropped noticeably in the last years, the projector is nevertheless the most expensive part of a multitouch surface.

Indeed there have been some successful attempts of making a mutitouch surface using LCD matrices, further reducing cost of the hardware. This approach, however, has two problems in my opinion: the resulting screens are relatively small and there is a problem with background illumination. Fortunately working in a laboratory on a faculty helps a lot with this kind of issues and we were able to test a few projectors to see what would fit the best.

Logically the most important characteristic of the projector is the focal length followed by keystone flexibility. The space behind the actual surface is usually very limited. In our case the table scenario imposes a practical height limit of approximately 1m. This is the height that a standing person of average height would consider comfortable. Because it is extremely hard to find a projector that would produce a 80x60 cm image at the distance of cca. 80 cm we decided to use a mirror and double that distance. Even in this configuration only some projectors are suitable, so if you decide to go this way be sure to test the projector first.

To conclude this (rather meaningless ... but it was on my list) post: I have uploaded some additional photos regarding our project in my gallery ... as you can see from them, we have already started to make the side walls and to put everything in place. I will talk some more about this in my next post that will deal with all this.