Tuesday, March 13, 2007

Transparent info boards

Tavis over on the WFA has mentioned information boards for any proposed trail and got a tad excited about it. Use transparent boards to point out features on a building. It's a great idea, and in theory will work; except for one or two small drawbacks. Using my Crown House pictures from Flickr I knocked up a quick simulation POV-Ray. the building is 15mx25m, the camera is 32m away from it. The information board is .5m square and 1.5m from the camera.

At a height of 1.8m looking straight ahead.
Everything looks fine. Now how about at a height of 1.7m looking at the same point as before.

Damn, this is with a difference of only 10cm. I can't rotate the board to bring the roof in line without moving the floor up. Even lowering the board starts to cause problems and I'd hate to be the engineer who worked on that board.

I'm not dis'ing the idea, it'll work provided you're standing at the one point it works at, that means you need the something like two small crosses on either side of the glass which you line up and a stand-here cross on the pavement. I'm afraid I think a simple photo would turn out to be easier.

2 comments:

Tavis Pitt said...

It was encouraging but also scary when I mentioned my idea to an expert. Once he got the idea he was ecstatic and I only asked if it would work. He went on, jumping up and down, that it could work with a LCD screen, maybe only requiring a back light shone from the ground. With a LCD screen not only would you have moving images, but you would also be able to adjust the angle to the high of the viewer. First we he thought of a chin rest but that would be uncomfortable for people too short and people too tall. Then he went hi-tech, a retina scan from the board could be used to locate the viewer’s eye level and adjust the images accordingly.
Add speakers and a CPU and you get spoken dialogue (in many different languages)!

FlipC said...

Heh experts are great when dealing with their own field. So you'd need a highly directional back-light that's resilient to foot traffic. A tough unbreakable screen that can be cleaned easily (perhaps two removable transparent panels).

Retina scans for people wearing glasses? A head level would be better, detect the round blob and assume the eyes are a third of the height down; you don't need to be too exact. Oh and a power source.

Avoiding the scan a four arrow buttons and a 'line up the crosses' might be easier, you can then use the arrows to navigate too.

All that and it'd still only work for one or two people at a time.

Would be nice to see though.