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Build Your Own Multi-touch Surface Computer

By - Source: Tom's Hardware US | B 17 comments

Maximum PC didn't feel like shelling out $12,000 for Microsoft's Surface technology, so the staff made its own multi-touch table PC for only $350

The online magazine's original task was to publish an article about future user interfaces. However, after extensive research into multi-touch applications such as Apple's iPhone and Microsoft Surface, the staff at Maximum PC uncovered a whole community of DIY engineers "perfecting the art" of creating homemade multi-touch surfaces. Home-built multi-touch surfaces should come as no surprise: there are websites dedicated to hands-on construction of unique technologies such as a Commodore 64 laptop, a speech-controlled trash can, and even a lemon-charged battery. Needless to say, if the industry can build it, then the online community will find a way to build even it better... and cheaper.

With that said, Maximum PC decided to create a multi-touch surface computer using methods found online at the Natural User Interface Group. Ultimately, the online magazine didn't go out and spend $12,000, but rather just $350. Out of various processes used to construct the homemade multi-touch surface, the staff decided to use the FTIR (Frustrated Total Internal Reflection) screen setup. This consists of a sheet of transparent acrylic, a chain of infrared LEDs, and a camera with an IR sensor. According to the site, the LEDs are arranged around the outside of the acrylic sheet so that they shine directly into the side. The IR light thus shoots into the acrylic, reflecting off the top and bottom of the material, remaining contained within.

When a finger presses against the sheet, the reflecting light hits the spot and bounces downward into the cabinet mounted underneath. A modified webcam mounted in the cabinet--altered to detect only infrared light--views the finger touch as white spots, and then sends the image to software running on a connected PC. The software maps the movements and applies the coordinates to whatever application is running. The PC thus transmits the on-screen image via a projector back onto the surface using a mirror and a piece of heat-absorbing glass. Granted this brief overview sounds rather simple, the process of creating the multi-touch surface PC takes a bit of work, from polishing the sides of the acrylic sheet to altering the webcam.

But wait... Maximum PC didn't just use any webcam; the site implemented the $35 PlayStation 3 Eye, using a rectangular razor blade to gain access to the poor camera's IR filter. As with the rest of the article, the site shows the step-by-step process of removing the unwanted filter. "The infrared sensor is the innermost piece of glass on the lens assembly," the site reads. "When it catches the light, it looks ruby red – a dead giveaway that this is the piece filtering out infrared light. In order to remove it we simply used a razor blade to gouge out the plastic in a circle around the filter, allowing us to easily pop it out." Why remove the filter? So that the PlayStation 3 Eye can pick up infrared light.

As for the connected computer, the staff didn't use anything meaty, only a PC containing a Core 2 Duo and 2 GB of memory. With that said, DIY builders won't need anything outrageously fast, but more than likely a rig that hit the market within the last few years. Additionally, the camera and PC don't necessarily need to be within the cabinet; the cables for the PS3 Eye and projector can run out of the cabinet and hook up to a laptop if needed.

Ultimately, the actual multi-touch screen was 24-inches by 30-inches, with the acrylic sheet 3/8-inches thick. The IR LEDs lining along each side were 1-inch apart, however the staff wired the LEDs together the hard way, soldering the leads together rather than just using a wire-wrap gun (that would make the task quicker and more environmentally safe... meaning no lead). The cabinet itself was constructed from 3/8-inch MDF, with a stained hardwood frame on top, standing waist high. To get the entire contraption to work, the team installed Touchlib on the PC, an open source library that takes the visual data received by the camera and parses it into touch events. Someone even wrote a driver that enables the PS3 Eye to work on the PC.

"We completed this project over the course of about two weeks' work," the article reads. "All said and done, everything worked out pretty well. We ended up with a fully functional, highly responsive multi-touch surface."

For a meager $350, the DIY multi-touch project sounds like great fun, and may end up as something we do here at Tom's just for kicks. After all, many of us don't have a whopping $12,000 stored in the underwear drawer (well, maybe Tuan). Still, this example definitely proves that anything is possible on a small budget. All it takes is a little patience, a little research, and a dedicated community to help along the way.

Display 17 Comments.
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  • 0 Hide
    08nwsula , April 7, 2009 11:15 PM
    video anyone?
  • 1 Hide
    08nwsula , April 7, 2009 11:17 PM
    http://www.vimeo.com/4030910
  • 0 Hide
    rigaudio , April 7, 2009 11:22 PM
    I've always wanted to build a multitouch table of my own. The projector, though, is the biggest cost.
  • 2 Hide
    jhansonxi , April 7, 2009 11:59 PM
    Very cool hardware project. Most OS platforms have support for multi-touch now so it's getting easier. Maximum PC is using Windows XP and the Touchlib library. X.org has added MPX support so it should be supported on most Linux distributions in the future (here is a video).
  • 1 Hide
    Shadow703793 , April 8, 2009 1:04 AM
    Nice! So many projects to do during summer.... will I have time(and money)? lol.
  • 1 Hide
    seboj , April 8, 2009 1:55 AM
    I don't have the time to research this whole thing right now, but would a beefier computer decrease the lag? Or is that just inherent from the way it works with the IR -> Computer -> Projector?
  • 0 Hide
    acecombat , April 8, 2009 4:49 AM
    Hmmm...looks like a project I might undertake when I'm bored in the near future :p 
  • 1 Hide
    Anonymous , April 8, 2009 5:04 AM
    Why not just use the nintendo wii controller instead of a camera, it is wireless and already tracks 4 points of inra-red and sends the co-ordinates back to the PC, far easier, almost no lag and works a treat, I've been doing this for a while, built an 'interactive' canvas to paint on. There is already drivers for OSX and Windows.
    http://johnnylee.net/projects/wii/
  • 0 Hide
    tayb , April 8, 2009 5:20 AM
    It's a fun project to do but it isn't actually anywhere near $350. The $350 doesn't include the PC or the projector.

    I found a cheap projector on craigslist for $200 and use a MacBook Pro running boot camp to accomplish this. The device is treated more like an accessory than a stand alone unit. Powering the LED's and what not is obviously quite a bit different than how they powered them but I think it is more ideal. I would rather be able to simply plug in the laptop and use the device when I wanted to rather than put a PC to waste in a machine I can't get any real work done on.
  • 0 Hide
    magicandy , April 8, 2009 5:44 AM
    I saw a guide on how to make your own cheap multitouch table on Gizmodo almost a year ago.....
  • -1 Hide
    thesmokingman14 , April 8, 2009 1:06 PM
    Sure, it's $350 for materials. But, your article states that it took them two weeks to build. Even if it only took one guy working 8 hours a day, 5 days a week, at $15 an hour, wages alone would be $1200. When you add the materials, their cost was really $1550, not $350. But, I'm betting the techies down at Maximum PC make significantly more than $15/hour, which actually put their cost over what they could have bought it for.....Just a thought on opportunity costs.
  • 1 Hide
    LuxZg , April 8, 2009 1:07 PM
    Yeah, I was wondering how come this article doesn't mention projector. t's still not a very cheap thing to do.. Yes, it will be a nice project if you really need touch-table, but as a "pet project" I think it's a little over the top.

    Though completing this thing shouldn't be hard with a SFF PC built into the table. If you're doing something this big, than better do it the right way from the start.

    Nice gizmo anyway, looking forward to reading and researching the whole thing once I get home :) 
  • 0 Hide
    Anonymous , April 8, 2009 7:07 PM
    rigaudioI've always wanted to build a multitouch table of my own. The projector, though, is the biggest cost.

    +1,a good projector eats more than the table costs you in parts.
    I think if someone would sell this concept it might go for $2000 with a +/- $1000 projector included.
  • 1 Hide
    mindless728 , April 8, 2009 9:05 PM
    if i didn't just build a new computer, this would be a good project for spring break right now
  • 1 Hide
    kamkal , April 9, 2009 12:26 AM

    thats major pwnage right there.
  • 1 Hide
    pocketdrummer , April 9, 2009 7:54 AM
    Isn't this kind of Article stealing?
  • 0 Hide
    Anonymous , June 6, 2012 12:13 PM
    just wondering can u use any projector for the touchscreen