FTIR coffee table
Posted: 15 June 2012 12:01 AM   [ Ignore ]
Joined  2012-06-04
Total Posts:  2
New Member

Hi nui group!

I have known about this technology and the methodology behind this for a while now (and thought it was quite ingenious when I read about it years ago), and have wanted to implement it.

I was given an older dell 20 or 22” monitor a couple years back, and realized it was perfect for what I wanted to do. It sat, and sat, and sat, for literally years collecting dust in my closet. I finally took the time to disassemble it to the bare lcd, and controller, and realized I was going to have issues with the flex cable being much too short to allow for the lcd to work and not have the matrix boards obstructing too much of the boards. I went onto digikey, and bought a flex cable that matched the same dimensions that I needed (and 8 inches long vs like 1.5 inches) for $8, (i needed 30 cents worth of other parts for another project, but couldn’t justify spending $8 on shipping for 30 cents, so I figured I may as well try with the cable). Well it came in and it works perfectly.

now I am just sort of in the imagination stage/design stage where I need to sit down and really think out the logistics of how I will be assembling the table, buy the parts, build up a test rig, and then once everything works, draw up a nice looking design for a coffee table with the screen in the center. I need a table for my new college apartment, so may as well implement the screen into it and have it be really impressive to guests.

My main goal as of right now is to have a very user friendly interface, which I think windows 8 will be perfect for. Fun multitouch apps like google earth, maybe some games, a multitouch internet browser, and I would also like for it to run xbmc, where it outputs the video to the tv via one of those wireless hdmi outlets. Another thing I saw that was pretty cool was a mathematics program called “hands-on mathematics” that was being developed by some people at brown university. It would be very nice to do my engineering homework using my multitouch table as a very strong tool.

Any informative links you could give me to read would be greatly appreciated. Thanks.

Posted: 15 June 2012 02:45 PM   [ Ignore ]   [ # 1 ]
Joined  2012-06-12
Total Posts:  13
New Member

Sounds like you and I are in the same boat. I’m going to go buy some acrylic later today at a local plastics superstore. I am pretty sure I am going to go with an LLP for my first time. I was dead set on FTIR for a while, but if you want to use drag gestures or any type of paint program, photo manipulator, exc you will need to use a compliant surface when using FTIR. This isn’t a problem when using a projector, but I would think that a compliant surface would distort the LCD image. I haven’t built a table yet, however, and I’m sure my knowledge would be easily surpassed by any of the more experienced members here.

I’m glad you brought up the idea of using Windows 8 on a MT surface, because now I’m thinking of trying it myself. I don’t think I would use Windows 8 on my main machine, but it may be a perfect fit for MT tables.

I would like to see how your project works out! Good luck!

Posted: 16 June 2012 05:02 PM   [ Ignore ]   [ # 2 ]
Joined  2012-06-04
Total Posts:  2
New Member

I actually did a bunch of reading on that today, and I think I’ll go with a DSI setup. It was the original idea that I first heard about, and liked it the most, ftir just sounded a little easier. But I spend most of today thinking up a design, and got some progress done in sketch-up, so I’m gonna upload the pictures. Sounds like DSI has problems with glass on top, but many people use the abrasion resistant acrylite anyways, so I can still have the original design that I wanted, which I couldn’t do with ftir, but I don’t really wanna drop a ton of money, so I downsized it a little bit. not its more like a smaller table that will sit in front of a sofa chair or a couch. Here’s a couple pictures with a couch that I downloaded and scaled to about the size of my couch:





Some more things I still need to read up on if people want to help me out:

What is a ghosting point?

What are the best types of cameras/most cost efficient ones to modify besides the ps3 eye?

Are there any webcams that don’t already have an IR filter? Possibly cheap ebay ones?

I will probably need 2 cameras because I don’t want to have 2’ of space from ground to table. Right now it is at 15” and I don’t want to go much higher. How hard is it to configure a multiple camera setup with respect to a one camera setup?

Posted: 18 June 2012 04:58 PM   [ Ignore ]   [ # 3 ]
Joined  2008-09-12
Total Posts:  2225

Your Endlighten and LCD layers need to be flipped.  LCDs cannot pass IR light from beneath it unless they are modified at the factory, hence why you can’t build a Rear DI LCD setup.  It should be top to bottom: AR->Endlighten->LCD->Diffuser From Backlight->Support Clear Acrylic (if needed).

Don’t know exactly what you mean by a ghosting point but perhaps you’re talking about a blob that is not caused from the user directly interacting with the screen, such as a reflection off something inside the table, a stray beam of sunlight hitting the screen, etc.

Can’t beat the price vs performance of a modified PS Eye camera.  Go for an upgraded m12 lens setup, you won’t be disappointed.

No, all web cameras typically come with the IR blocking filter inside them, hence the modification to the OEM original lens that needs to be done (or the full replacement of the lens setup = best results).

With CCV 1.5 a multiple cameras setup is very easy to implement, just make sure the lenses don’t have too much distortion in them (a focal length of 2.8mm or higher is recommended).


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