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Wiimote as Multi-Touch Display Controller 107

Posted by Soulskill
from the amazing-home-projects dept.
Tmack writes "While hard-hacks with the Wiimote are somewhat old news, this particular implementation is quite interesting. Using the infrared camera on the Wiimote, pens with LEDs instead of ink, and an LCD projector, Johnny Chung Lee of Carnegie Mellon University has created software to use them as a (relatively) cheap multi-touch display. Any surface onto which you can project becomes an interactive multi-touch display, as demonstrated in the video at the link. He has the software available for download, along with some other neat projects. Lee has also documented another impressive Wiimote hack.
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Wiimote as Multi-Touch Display Controller

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  • by FatAlb3rt (533682) on Wednesday December 19, 2007 @10:40AM (#21751204) Homepage
    What's this...a way to pass time until the demand for the Wii consoles goes down enough that I don't have to crawl over people to get one? Sign me up!

    Oh...the Wiimotes are out of stock too? *walking away, hanging head*
    • Re: (Score:2, Funny)

      There, there. On to the good news: we still have plenty of PS3's in stock, Mr. Alb3rt.

    • Oh...the Wiimotes are out of stock too? *walking away, hanging head*

      I presume you're making a joke on this part, and you've been accordingly modded +2 funny. But I thought I'd mention that by my own experiences, the wiimotes have been consistently well stocked, even with the wiis sold out constantly. Apparently it is nowhere near as difficult for nintendo to make the wiimotes as is it to make the wii itself...
      • Re: (Score:3, Insightful)

        by ByOhTek (1181381)
        or Nintendo predicted a higher demand for the Wiimotes

        either
        (A) the Wiis are used less for multiplayer than Nintendo expected
        or
        (B) the Wiimotes have a higher survival rate than Nintendo expected
        or
        (C) A+B
        • Re: (Score:2, Funny)

          I particularly like option

          (B) the Wiimotes have a higher survival rate than Nintendo expected

          Since this could imply that perhaps Nintendo expected more people to (inadvertently) send their wiimotes crashing through their TVs or sailing across the room...
          • by ByOhTek (1181381)
            inadvertantly, or intentionally.

            I have to admit, I'm quite annoyed with the detection on mine. I keep wanting to bash the thing against my coffee table because it won't detect that it is pointing at the screen.
            • I have to admit, I'm quite annoyed with the detection on mine. I keep wanting to bash the thing against my coffee table because it won't detect that it is pointing at the screen.

              Unfortunately, I cannot relate to this, as I have not been able to buy a wii for myself thus far. Your comment does remind me of my days with the good ol' NES, however. I know I intentionally swung those controllers around by their cords and bashed them on the floor for not working correctly.

              I know there were many times where poor Ryu Hayabusa fell into one of many bottomless pits because the timing just wasn't right for the A button on those controllers. Even the "slow motion" feature on the "NES A

              • by beckerist (985855) on Wednesday December 19, 2007 @06:45PM (#21757774) Homepage
                Oh man I used to throw my 64 controllers in hissy fits of rage. Whoever the fuck had to play as Oddjob [wikipedia.org] every god damn time was nothing short of a cheater! (Yes, the pun was intended!)
                • by tepples (727027)

                  Oh man I used to throw my 64 controllers in hissy fits of rage. Whoever the fuck had to play as Oddjob every god damn time was nothing short of a cheater! (Yes, the pun was intended!)
                  That was just stupid. A Goldeneye player who wants a more subtle advantage can play as Civilian #1, the little girl.
            • Re: (Score:2, Informative)

              by gallwapa (909389)
              semi OT, but...

              A few notes if you're having trouble:

              First, make sure your IR sources don't confuse the wiimote. Example: Opening my drapes on the window behind the TV on a warm, sunny day, made the wiimote useless.

              Second, set the proper height for the "sensor" bar in the Wii console itself. It does make a difference, especially if you have a large TV

              Third, make sure your batteries are properly charged. Don't wait for the warning to go to red. When it gets to 1 bar, put the batteries in the recharger.

              T
              • by HTH NE1 (675604)

                The "IR Pollution" is the biggest factor affecting the performance of your wiimote, in addition to distance.

                It also affects the ability of a TiVo to control an external tuner like a cable box with IR properly. Even if the cable box cannot see the source of the IR pollution, if the TiVo can see it, it cannot send the signal to change channels until that pollution goes away (IR bus busy).

                So be careful how you set up your Wii sensor bar with respect to any TiVos that control external tuners with IR signals.

                Before the Wii, another source of this problem was wireless IR repeaters that would turn any radio noise they

            • by AKAImBatman (238306) <akaimbatmanNO@SPAMgmail.com> on Wednesday December 19, 2007 @12:21PM (#21752348) Homepage Journal

              I keep wanting to bash the thing against my coffee table because it won't detect that it is pointing at the screen.

              Check that there are no bright IR light sources nearby. Sunlight and Christmas lights are two common ones that confuse the Wii Remote. Also make sure that your Sensor Bar is far enough forward that it isn't blocked at certain angles.

              An easy way to figure things out is to go into the Wii Remote settings screen. There's a black and white image there that effectively shows you exactly what the Wii Remote "sees". You should see a few dots that do not flicker or go away as you move the remote around. If the dots disappear at any point during your tests, you may need to adjust your sensor bar.

              If the lights appear to be working okay, but the remote is still confused, try turning down the sensitivity of the remote. That will encourage the remote to ignore light sources other than the sensor bar.
              • by ByOhTek (1181381)
                That's useful, thanks.

                Actually, my problem is how close I have to be. They should make a smaller "nearsighted" bar.

                Since I got my replacement contact lenses (and can focus at larger distances), it's better, though still not perfect. They need to make a sensor-bar mini, that's half the width, designed for closer use.
                • by bcat24 (914105)
                  You've probably already tried this, but if not, try going into your Wii's settings and adjusting the Wiimote's sensitivity.
                • by Rynth (1092427)
                  Or perhaps a sensor mini-bar, so those tired sensors can kick back and have a drink.
                • Actually, my problem is how close I have to be.

                  Ah, I see how that could be a problem. The minimum distance is really about 4-5 feet from the screen. Even then, you pretty much need to be in a chair to play effectively.

                  Possibly the best advice I can give you is this: Get a bigger TV. :-)
                  • by ByOhTek (1181381)
                    47" is already particularly absurd for my living room... And about the top of my budget
                    • 47" is definitely a good size. Exactly how close are you to the TV? If you used your Wii Remote at the same distance I do during development (I have a 15" LCD Monitor), you're going to have a fully-immersive experience! :-P

                      If your TV is big enough and you're standing at least 4 feet away, then its probably your sensor bar. Either there is too back background IR light, or the bar is becoming invisible at certain angles. If it's the latter, you can try one of two things:

                      1. Move the sensor bar closer to the ed
                • by pavon (30274)
                  The bar itself is nothing but two IR LEDs, so it shouldn't be difficult to build or modify an existing bar to be any length you wish. I've even seen someone who managed to get the Wii to work with two candles placed on top of the TV :)
                • by CityZen (464761)
                  The problem with being too close is not that the bar is too big, but rather that the field of view of the camera in the Wiimote is too small.

                  Imagine a cone growing out from the front of the Wiimote. The further you are away from the sensor, the more likely that the sensor is seen within this cone. The closer you get, the more likely the sensor is outside of the cone.

                  For most pointing applications, the Wiimote only needs to see one end of the bar or another. Some applications might use the sightings of th
                  • Some applications might use the sightings of the two ends to calculate how far away you are from the TV, or what the rotation of the Wiimote is with respect to the bar, but I'd imagine these are rare.
                    Rare? Hardly. Wii Menu is one of them. Try rolling the Wii Remote while pointing it at the screen. Or in Wii Play, try Pose Mii and Laser Hockey.
                    • by CityZen (464761)
                      That's interesting.

                      One question is whether these apps require sighting the two points or not.
                      They can also get the rotation data from the accelerometer.
                      Can you experiment with covering up one end of the sensor bar to see if those things still work?
                    • by tepples (727027)

                      One question is whether these apps require sighting the two points or not.
                      They can also get the rotation data from the accelerometer.
                      Can you experiment with covering up one end of the sensor bar to see if those things still work?

                      Both. In Wii Menu, when I use both emitters, the hand cursor responds immediately to roll. When I use only one emitter, the hand cursor responds much more slowly, as if it is trying to filter out accelerometer noise. If I cover up one emitter on Wii Play's menu and then point the Wii Remote at one emitter, the cursor doesn't show up until I uncover the second emitter. In Pose Mii, if I cover up one emitter, my Mii responds to roll but spins in place until I uncover the other emitter.

          • No, they just didn't expect the Wiimotes to survive.

            They've made a secret deal with Sony. Sony doesn't compete with them in the console business, Nintendo creates an artificial demand for new televisions. Win-win.
        • D) people are hoarding Wii base systems to ebay them and not play them. Nintendo is making balanced shipments based on the titles they know are selling, say, 2 extra wiimotes per system. Extras are on the shelf because Wiis are not being bought by players. Note in the early days, separate Wiimotes went about as fast as Wiis as most people bought a Wii then went back a few days later for the extra remotes. I'd doubt Nintendo is making MORE than 4:1 extra wiimotes.
      • by telchine (719345)

        Oh...the Wiimotes are out of stock too? *walking away, hanging head*

        I presume you're making a joke on this part, and you've been accordingly modded +2 funny. But I thought I'd mention that by my own experiences, the wiimotes have been consistently well stocked

        I suspect that the original poster may be in a different country to yourself.

        I live in the UK and have bought both a Wii and a Wiimote in the last week. The Wii was hard to get hold of, but nowhere near as hard to get hold of as the Wiimote. Eventua

    • by DrWho520 (655973) on Wednesday December 19, 2007 @11:12AM (#21751526) Journal
      I have seen Wiimotes everywhere, Buy Buy, Circuit City, Target and Walmart. Maybe they should contract to the Wiimote manufacturer to also start cranking out Wii's.
    • by joaommp (685612)
      It's gonna be the "Multii-Mote"
    • by Smidge204 (605297) on Wednesday December 19, 2007 @12:30PM (#21752452) Journal
      Just about any CMOS webcam can be easily modified to see only IR light. It involves removing the IR filter (usually a small glass plate with special coating inside the lens assembly) and adding a filter to block visible light (usually a fully exposed piece of film negative).

      =Smidge=
    • My friend at work has bought 5 Wii at Walmart (not all at once of course). You simply need to know when the delivery takes place and hang out at the store until they bring them out. Actually, he got six. He got one for me and then GAVE IT BACK when he couldn't contact me on my cell to see if I wanted it! No problem; he just got another one for me the following week. This morning he picked one up for our boss to give to his son. Now that's job security!
  • by imstanny (722685) on Wednesday December 19, 2007 @10:49AM (#21751294)
    The Wii-mote is actually a sensor that is used as a remote. It doesn't just send a signal, but rather it 'sees' the location of the 'motion detection' bar. In the traditional usage, it has only 1 point that it detects - the bar. But if you have 'many of these bars' the Wiimote is used as a detector of multi-inputs.
    • by Paralizer (792155) on Wednesday December 19, 2007 @11:01AM (#21751420) Homepage
      The sensor bar has two IR points on either end to help with calculating things like distance. The wiimote itself can see up to 4 IR sources at any given time. So the multitouch interface would be limited to 4 pens, not that you'd need more than that though.
      • they have size... (Score:3, Informative)

        by emj (15659)
        ... you see how big/close they are as well, so it's not just position.
        • by ug333 (919867)
          Umm, no. It knows the distance between the two points on the sensor bar. Their location relative to each other is used to calculate distance. If you do anything to provide 2 IR sources that are farther apart, it will behave like you are closer to the screen.
        • Re:they have size... (Score:5, Informative)

          by slim (1652) <`ten.puntrah' `ta' `nhoj'> on Wednesday December 19, 2007 @12:04PM (#21752114) Homepage

          ... you see how big/close they are as well, so it's not just position.
          No, the Wii software expects the Wiimote to see two IR dots (one on each end of the 'sensor' bar). Everything is calculated from these two points. X/Y position is the X/Y position of the midpoint between the two dots. Roll is the angle between the two dots. Z position (closeness) is the distance between the two dots.
          • You can get other kinds of data [wiili.org], it's just not that usefull as the x/y coordinates.
          • by Smidge204 (605297)
            Pitch and roll are handled by internal gravity-sensing accelerometers. The bar is used only for yaw control because twisting the unit about the vertical axis has no effect on the perceived gravity for the accelerometers - that requires expensive gyroscopic-procession sensor units.

            I'm doubtful the Wiimote uses any information from the bar other than yaw. Calculating distance to the screen is perhaps possible but it would have to account for things like not being pointed directly AT the bar (perspective skew)
        • by Paralizer (792155)
          That is an option you can enable if you want that data. Looking at it though, it seems pretty general and doesn't give very accurate results. For example, you may have to move backward a couple of feet for it to drop to the next smallest size interval. If you are using the two IR sources to estimate distance you will have much better precision.
          • by emj (15659)
            Of course it's not precise, but still it does work if you want to track just one IR source. You need one that sends a constant amount if IR in all direction (lighter will work). It worked pretty well for me in the 30cm-90cm rangre..

            But using just x/y is just fine, and a lot more precise..
  • Motion capture? (Score:1, Insightful)

    by kesoil (612878)
    Wonder if someone has made software to use Wiimotes for motion capture. =)
    • by bwcbwc (601780)
      I'm getting that burning, trolling sensation, but I'll answer anyway: Don't the games on the Wii act as motion capture already? I suppose you want something you could merge into a 3-D environment of your own choosing, though.
  • My project (Score:3, Interesting)

    by pkadd (1203286) on Wednesday December 19, 2007 @11:00AM (#21751400) Homepage
    I am currently working on using a wii controller as primary pointing-device for my livingroom. The goal is to make it the only device needed to controll the projector + PC i use for DVD, TV, and Music playback in my home. I will post info when i've figured it all out.
    • by duckpoopy (585203)
      You should know that the wiimote does not emit infrared like normal remotes - in case that was your angle. The wiimote is an infrared camera. The IR emitters are in the sensor bar on top of your TV.
      • Re: (Score:3, Funny)

        by BobMcD (601576)
        That's nothing a little duct-tape can't fix!
      • by emj (15659)
        You can have three paintings on the wall, a phone, a radio and a TV, which all have different IR patterns. Then when you point you Wiimote on the phone painting, the Wii mote will see the pattern and tell your computer what you are pointing at. The computer will then activate the Twinkle (sip) on your computer and you can interface with it.. :-)

        Using the motion sensors to answer calls [engadget.com] might be a bit awkward (some minutes into the clip).
    • I've done this. It was the first thing I thought of when I learned how the Wiimotes worked.

      It's actually rather simple...
      1. First you need a sensor bar that is no dependent of your Wii. You can make one [google.com] or buy one [ebgames.com].
      2. You need a bluetooth module
      3. A driver to handle requests for your Wiimote and translate them into mouse movements, etc. Linux, Mac and Windows drivers [wiili.org]
      4. (optional) I mapped my buttons to multimedia keys and bound some of them to commands
      5. You need some software. In my case I've written my own call
  • by superid (46543) on Wednesday December 19, 2007 @11:16AM (#21751552) Homepage
    My own trival "hack". I'm using Darwiinremote [sourceforge.net] to read xyz accelerometer data and Octave [octave.og] to make/graph ffts of Parkinson's tremors. It's remarkably sensitive!

    • by Gravatron (716477)
      Reminds me of seeing the engineers at NIWeek using nunchucks and wiimotes as cheep accelerametors for some of the demonstrations. Analog Technologies, who makes the wiimot's accelerameter, was onhand at the convention, and had a blast seeing what all people were doing with it. Interestingly, when I brought up the sixaxis, they were somewhat interested in how it functioned. Almost makes me wish I had one on hand we could have picked apart.
  • Nice hack but that's pretty much how some existing surface computing devices work anyway. That a mass produced device is cheaper is nothing new.
    • Re:Nothing new... (Score:4, Insightful)

      by skorch (906936) on Wednesday December 19, 2007 @12:10PM (#21752208)
      Some of the most important innovations are not about making something completely novel but about coming up with creative and more efficient ways of using what we already have. If this hack reproduces 75% of the performance of a commercial product at a fraction of the cost, then this is already a more cost-effective solution for simple touch-screen presentation software. It also puts it well within reach of the at-home user and not something that can only even be considered for large corporate presentations. All of a sudden an 8ft sq canvas for digital art is not out of the question, and it's scalable to a simple laptop as a tablet-pc replacement.

      And considering the application he offers is free this can only encourage more experimentation that can lead to even more innovative applications of a relatively cheap and abundant product which is (Nintendo sanctioned or not) becoming more and more of a multi-purpose tool.
      • by emj (15659)
        If this hack reproduces 75% of the performance of a commercial product at a fraction of the cost,

        Actually it's alot better than most products on the market atm. Mainly because of the speed, it's insanely fast compared too some commercial options that only support one touch.. And if you look at many of the multi touch interfaces being done you will see that they almost always lag 0.1s or something...
    • by prelelat (201821)
      You never did like the TV show MacGyver did you? I don't think you understand the joy of hacking something together to do something it wasn't designed to do. Whats good about this is that you could use it to replace a 2000+ dollar device for 50 bucks. It may not be new but it's defiantly interesting and cool. I mean I could go home tonight and have a touchscreen on my computer(I have a wii and bluetooth).

      I think your just a negative Nancy.
  • by TheLostSamurai (1051736) on Wednesday December 19, 2007 @11:19AM (#21751578)
    When Johnny Lee posted his last hack [slashdot.org], it seemed like a cool idea to track your fingers in the air, but not all that practical, as was discussed at length. This hack however could actually have very practical applications for discussion and presentation, without the $5000 price tag of many interactive white board products. I'd like to see if anyone ever attempts to implement this in a small business environment, such as a design studio.
    • I bought one of those candy fan pens from blockbuster last night and converted it to an IR pen by replacing the motor with an IR led. Cost: $3 pen plus $1.50 LED. Works great! I put up instructions here: http://jordanbalagot.com/blog/2007/12/19/converted-diy-ir-pen-from-candy-toy/ [jordanbalagot.com]
      • by Evangelion (2145)
        I was looking at something like that, but what I ended up doing was getting a $1 LED pushbutton flashlight from the dollar store. It was literally just the LED and 2 batteries in a plastic casing. I was able to drop-in replace an IR emitter from radio shack without so much as touching a wire.

        We're going to try this in the office tomorrow. We would have done so today, but for some reason there were no Wiimotes around :-(
  • I'm so going to have to try this. The software isn't complex and with some work I'll finally have a giant digital canvas with the infrared pen acting as pen/airbrush.
  • I've got to believe that using this with photoshop is the best use...
    • by RingDev (879105)
      It will matter a lot on the resolution. He made a comment that the further away from the pen the remote is, the lower the resolution, so using this for Photoshop would work best with his personal setup where the remote was only ~3 feet away from the surface. Using an IR only LED would be a wise choice as well so you don't wind up with a red tinge to everything you try to click on.

      -Rick
    • by fzachman (551166)
      As a digital artist, I can say that while this is intriguing at first glance, it's not all that practical for artistic purposes. The reason people by Wacom's and pay so much for quality digitizing touch screens isn't just the motion tracking, it's pressure sensitivity. Without any way to track variances in pen pressure or angle, you're really limited in what you can do with it. It would remain a novelty at best.
    • Won't work for a long while, AFAIK photoshop doesn't have multitouch support.
  • The only problem, when you use this with a projector-based system, you're always casting shadows. It would be better as the presenter if you had a tablet PC replicating the screen display and you multi-touched on the tablet. Touch-sensitive screens are always ridiculously expensive so this might be a good way to keep it cheaper.

    I'm still waiting for the large-format flexy-screens that are as cheap as rolled paper. I love my LCD screens but they're just too damn expensive and fragile right now. I want 100" w
    • by Tony Hoyle (11698)
      Rear projection... most projectors can be setup for this (by allowing them to project a mirror image).

      It looks like an insanely cool hack, and using things you have lying around the house too.
    • by RingDev (879105)
      You ever hear of "rear projection"? Completely eliminates the shadow issue.

      -Rick
    • by skorch (906936)
      Rear projection has already been mentioned as a solution for the shadow casting. Another solution is to point the wiimote directly at your laptop screen and do the 4-point calibration on that, and just use your laptop as a tablet pc hooked up through the projector. Considerably cheaper than an actual tablet pc in both cases.
    • by thedohman (932417)
      I always hate when an instructor/lecturer/presenter is at the board with his/her back to the room.

      How about using an IR laser pointer from behind the audience? the dot reflects the IR, the Wiimote picks it up.

      maybe a combo green/IR pointer, with the IR is switched separately from the green. That way, the green dot is your cursor. (otherwise you're clicking blind)

      But yeah, I love this. inset an LCD display into a desk, and have a mount for the Wiimote at the back of the desk. Who needs a mouse? (hm
  • The code to connect the Wiimote to your PC was already written by some other guy (you can find out who if you follow the links on the first guys website). The Wiimote was already capable of detecting IR light. The only hardware that he "hacked" was to make a pen light. Which is simply a power source, a current limiting resistor, a switch, and an IR LED. I haven't seen the white board software. Is there a video on the blog? There is an error loading the page for me. But I am guessing it turns the output
    • I don't think the idea is to use these pens to write twice as fast O_O.

      Have you truly never used both hands at once for a task?
    • by grumbel (592662)
      ### It seems to me humans are much more efficient at moving one hand at a time.

      That is only true when the motion of both hands are completly independent of each other. Human brain is doing quite fine with using both hands at once for a single task (trying typing with a single hand or opening a bottle with just a single hand).

      ### I think the usefulness of multi-touch displays is limited.

      Go and watch this demo video [youtube.com], now with a Wiimote you are limited to four points so many stuff seen there won't work, but al
      • That is only true when the motion of both hands are completly independent of each other. Human brain is doing quite fine with using both hands at once for a single task (trying typing with a single hand or opening a bottle with just a single hand).

        About opening jars you are definitely right, but about typing I have to disagree. If you are a halfway decent typist you have the layout of the keyboard memorized. A multi-touch display is only useful if the content it displays changes (making it impossible to

        • by grumbel (592662)
          ### If it were better to use 2 pointers, we'd all be using two mouses right now.

          I suggest you go and watch the demo video [youtube.com], it really gives some extremely simple and powerful example uses of multitouch and also makes it clear why that wouldn't be possible with a indirect pointing device such as a mouse. Look especially at the rotation and zooming and you will understand that there is no need to search for an object for both fingers.
    • I think it gets interesting to be able to have multiple people writing at once. Win, lose, or draw?

      It also might be interesting to use for zooming purposes. You can see the big picture as well as a box showing a portion of the big picture zoomed in to work on details...but moving that portion to where you want can be a pain in a lot of programs. While I couldn't write with two pens I think I could accurately move my one hand to the general area that I want to work on and hold it there or slide it occasi
    • Actually, I have a second cousin that can write from the middle of a sentence out with both hands. Insane, but true.

      Now, since that is far from common, I'll address the real issue with your post: limited creativity. Humans use their hands for multiple purposes quite often. Hands are actually designed for independent use. Your example of rubbing your stomach and patting your head at the same time is more of a question of how the arms are designed to work in tandem, this is more of a balance-oriented featu
  • I played a gig on sunday night, electronic peices with software synths. The venue manger moaned that my performance wasn't visual enough. This wiimote tracker could be better than Jarres laser harp!
  • this guy forgot to mention a couple things about this hack:

    * it can not distinguish between the different pointers
    * wiimote can only track up to 4 sources
    * nothing can get inbetween the line of sight of a pointer and the wiimote

    if you watch the video carefully the author carefully does not cross his arms, this is because if he does he will line of sight (LOS in wow speak) the other pointer.

    a fix to this could be to put the projector below a table and project upwards (inverted) on a g
    • by thedohman (932417)
      He does mention that the Wiimote line of sight can't be blocked. That was his explanation for setting it to the side.

      point taken on the other issues though.
    • He does mention near the beginning of the video I watched that when you set up the wiimote you have to be sure it has an unobstructed view of the pointers. It's near the same time he says the wiimote has a 40 degree (iirc) field of vision and the further away it is the less resolution you get.

      a fix to this could be to put the projector below a table and project upwards (inverted) on a glass surface so there is no change of LOSing any of the pointers.

      I actually thought that was where he'd go with it.

    • * nothing can get inbetween the line of sight of a pointer and the wiimote
      Given that wiimotes are relatively cheap, I wonder if this could be worked around by using multiple wiimotes from different angles and reconciling the data in software.
  • If you have two wiimotes, one located 45 degrees to your left, one 45 degrees to your right, wouldn't the appropriate math be able to locate the position of your pen in 3 dimensions?

    Normally I just nod and appreciate these hacking projects from a distance, but I think I'm going to jump in and do this for myself. Wish me luck, everybody.
    • by CityZen (464761)
      Yes, that is how most IR-based motion tracking systems work.

      Each point in each sensor corresponds to a known ray in space.
      To find the point, you need to know which points correspond to
      each other from the different views (this is easy if there's
      only one point in each view), and then you calculate the midpoint
      of the line that's perpendicular to both rays.

      There's lots of research on this topic. For really good results,
      you might want to investigate the Kalman filter. It's a
      predictor-corrector algorithm that a
    • by CityZen (464761)
      Oh, and another way to track an object in 3D with IR is to track multiple points (at least 3)
      whose relative position is known. This what the TrackIR does.
  • People always joke about this, and I see that it doesn't. The c# gave me a little hope thinking maybe it could run with mono but it uses direct x. I'm wondering if there are any wii mote hacks for linux.
  • I can't believe I'm the only person who sees the infinite applications of this!
    If this code were ported to Linux (which it will be soon) and you were using MPX, [unisa.edu.au] you could have a multi input computer!

    The thing about this is that now there is ONLY software standing between me and this! [perceptivepixel.com]
  • I made something similar in using python and a webcam. My hack was pretty simple:
    1) IR webcam
    2) IR-pen, similar to this guy's
    3) software in python to track the IR light
    4) demo-apps in pygame (tracking, swinging, 2 player pong)

    It worked pretty well to be honest. I also atached some LED's to a wireless mouse and controlled the mouse from distance (similar to but not as good as the wii-mote).I tried to add multiple inputs using one cam by using color video input and color LED's instead of IR LED's, but then sc
    • It would be great if you could post your source code somewhere along with some description (and maybe even pics) of your setup.

      I'm currently (and very slowly) working on an FTIR multitouch interface, similar to the stuff at NUI Group [nuigroup.com] but haven't gotten to the software part yet. They have libs there, but I'd be very interested in seeing your python stuff, as I'd much rather work in Python :).

      Also, the IR pen setup should be quicker to build than the FTIR setup. I was especially impressed when I first
      • by jedie (546466)
        where should I put the sourcecode? I don't have any documentation to be honest, but I do have some demos. If you have the time and patience you could easily figure out how it works. You should keep in mind though that the resolution of the motion detection is limited to the resolution of the webcam. A more interesting hack would be to simulate what the Wii does (ie having an IR emitter and have a webcam track those) but that would be infringing patents I believe. I'm pretty busy lately (working on my disse
        • How much source code is it? I've been poking around a bit trying to find somewhere that would be quick and easy; Sourceforge definately isn't, google code is better, but I don't think version control is really needed here. I did find http://codeviewer.org/ [codeviewer.org] which seems like it might work if there isn't too much code, though it's definately not very permanent.

          Seems like most of what I found is geared toward snippets, or full source code management. I wonder if anyone else here knows a good place?

          Don't worr
          • by jedie (546466)
            ok, here's one more question: how do I make sure that you don't go running off with my code? :) The library is pretty small and then there are some small examples. How can you be so sure that you can figure out how it works? I'm a pretty messy coder Don't mind me being a bit paranoid about this, I'm nex at this :)
  • 1) old news...i finished building mine a week ago 2) i hate 4 point orientation, i need to tear apart his source so i can make it read 9 points as opposed to 4.
    • 1) old news...i finished building mine a week ago
      2) i hate 4 point orientation, i need to tear apart his source so i can make it read 9 points as opposed to 4.
      That would require tearing apart the wiimote too. AIUI, the wiimote can only track 4 sources.
      • not at all, all i have to do is change the source to base orientation off of 9 ref. points, instead of 4. the four point orientation has nothing to do with the fact that the wiimote can only track four points. the four points means it can track up to four separate points, not reference the position off of 4 locations stored in memory of the computer...using your logic if you use the multi touch, it is tracking 8 points.
  • If you had multiple wii-motes they could resolve a higher resolution by doing some averaging in the software. Also you would not have to worry as much about blocking the wii-mote.

I'd rather just believe that it's done by little elves running around.

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