Meant to be Seen

Hey, had a random idea for a cool augmented reality display.

Basically what I 'm thinking is a head-mounted projector (top mounted), which projects on a half-silvered mirror (45 degree angle). Stuff like this has been done before, at least with desktop setups. My spin on it would be to have a mono-chrome LCD display in front of the projector to block the excess light (i.e. black out around the silhouette of an avatar). Then have another mono-chrome LCD in back of the mirror, to block out the inside of the silhouette. This would have the effect of making the virtual object opaque (instead of transparent like with the Vuzix STAR) and also not projecting extra light on the glasses (which would give an unsightly frame to the scene). I think this could work very well with the right technology.

So, does this sound even remotely possible? If I were to take apart a consumer-grade LCD panel, would there be transparent areas not activated (like with digital watches) or is this another type of screen? Surely its theoretically possible, but I'm wondering if its reasonable to think someone could DIY this. Any thoughts?

Makes sense, is what you are saying is basically have a backdrop that is alterable between opaque and transparent, and that way you can have greater brightness etc on the virtual objects?

What I actually like about this idea is that depending on how opaque you set the LCD you can actually add alpha to your scene programmatically rather than just having support for it in software which is very cool. Basically render an alpha buffer to the LCD. Cool idea!

It would be a blurry silhouette because the proximity of the lcd to the lens would throw off the focus.

The could be side-stepped if the projection system was a laser projection system like http://lightblueoptics.com/

But I still think you'll have light leak through. If it didn't, then existing LCD projectors would be able to achieve true blacks.

A big problem that comes to mind is that the LCD used to make the projection opaque is still going to have a lot of light loss, so you could only use it in bright environments, and it will not blend seamlessly.

There are some graphical LCD modules with very high transparency (Like the ones used in graphic calculators), though they are very low resolution. Would be very cool to try out, I will put it on the list of things to try out for a few hours when I just can't stay focused on my main work.

Ideally, a DLP based projector, when properly calibrated, should have a black level of 0. Same with CRT projectors (though they are far too bulky to head-mount!). Then you would only need the projection surface panel.