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So now we’ve completed the hardware section. The process of building a multi-touch computer is far from over, though, we need to get the software installed and configured so that we can actually use the thing.
The central software that powered our rig is Touchlib, an open source library which takes the visual data received by the camera and parses it into touch events, which can be used by other programs to provide multi-touch control. Some programs implement this library directly, allowing for standalone multi-touch apps, while others, such as those written in ActionScript, require an extra software layer to allow the program to receive touch input. In this section, we’ll explain how we got both up and running.
But, there’s something else we had to take care of first. The PS3 Eye, as we mentioned earlier, is a fantastic fit for this project because of its high resolution, impressive framerate, and ease of modification. There’s just one problem: it’s meant to be used on a PlayStation 3, not a computer.
Fortunately, PC users are famously unconcerned with what things are “meant to” do, and enterprising multi-toucher Alex Popovich has written a driver that allows the PS3 eye to be used with a computer. To get it working, we followed these steps:
1. Download the PS3EyeSetup file here. The download link is a ways down the page, in red, just above the comments section.
2. Make sure that the modified PS3 Eye isn’t plugged into the computer, and then run the executable. Plug the PS3 Eye back in. If the Windows found new hardware wizard pops up, tell it to search for drivers manually, and point it to the folder we installed the drivers in (C:/Program Files/AlexP/Drivers).
3. Now, we’ll want to test to make sure that the drivers are working and that our computer can see the PS3 Eye. To do this, run the PS3Eye Test App included with the driver. Because we’ve already modified the camera, you probably won’t see anything on the screen unless we point the camera at a source of infrared light, such as a light bulb or a sunny window.
4. Now that we know the camera works, we need to check to see that the DirectShow filter works, which will allow other programs to access the PS3 Eye. There’s another program called AmCap installed with the drivers. Run it, and if the preview view shows what the camera is seeing, we’re golden. If it doesn’t, try unplugging the PS3 Eye and plugging it back in, as well as rebooting your computer. For reasons unknown, the first time we tried, we got stuck at this stage. For us, running the uninstall program, then installing the drivers again fixed the problem.
Now we'd gotten our PS3Eye up and running. Next, we had to get Touchlib set up to handle our touch detection. Touchlib can be found here, and doesn’t need to be installed. We simply extracted the files to C:/Multitouch.
We had to replace certain Touchlib files with ones specifically designed to work well with the PS3 Eye. We downloaded these files here, then extracted them to C:/Multitouch/touchlib, overwriting when we were prompted to do so.
Now, at long last, we’ll get to see how our surface actually works. We ran ConfigApp.exe from C:/Multitouch/Touchlib. This program launches a total of eight windows, six of which are the video stream from the PS3 Eye, at different stages of processing. It’s a little over whelming the first time, but it’s actually not that hard to use these to get Touchlib properly configured to do touch recognition on our setup.
The most important window is the one in the bottom right, with the slider marked “Rectify” is the one that’s most significant. This window displays the “blobs” that will get passed as touch events. When the touch surface is working properly, this window will be entirely black until we touch the screen, at which point a white blob will appear, hopefully without flickering. Starting with the window in the bottom left, and moving right, we adjusted all the sliders so that we got the clearest blobs when you touch the screen. Generally, we accomplished this by playing with each slider until we started to get background noise on the Rectify window, then scaled it back slightly. Once you’re happy with the sensitivity of your screen, it’s time to calibrate.
Calibration is necessary to sync up the projected image and the touch surface. To calibrate, we first pressed the Enter key. This enables full screen mode, and displays a grid of green crosses. To begin calibration, we pressed the ‘c’ key. One of the crosses on the display turns red. By pressing on the dot, Touchlib is able to map that point in projector space to a point in camera space. The next cross will turn red, and this continues until all crosses have been pressed. We learned the hard way that when you’re done calibrating Touchlib, you must press the escape key. If you close the program any other way, it won’t update the config file with your changes.
Now our surface had been be properly configured (at least until we moved the camera or projector, or the lighting conditions changed significantly). To test it out, we ran the smoke.exe app in the Touchlib folder. With everything calibrated properly, colored “smoke” particle effects were displayed on our surface everywhere we touched.
However, we didn’t let ourselves celebrate for too long, because many apps written for the multi-touch surface are coded in the ActionScript language used by Adobe Flash. These programs are not set up to natively use multi-touch data, so we had to use a software layer to allow the flash-based apps to work properly. This is a three step process:
1. Change Flash’s global security settings to allow the flash apps access to the touch data. Go to this page and click the “Edit locations…” dropdown box, then select “Add Location,” then “Browse for folders.” Browse to the folder containing the flash programs you want to run, which by default is C:/Multitouch/Clients. This only has to be done once.
2. Run OSC.exe from the touchlib folder. This is an implementation of a protocol called OpenSound Control, which was originally designed to allow musical instruments to interface with computers, but can also be used to (among other things) allow programs to access multi-touch input data. This needs to be run any time you want to use a multi-touch flash app.
3. Run FlashOSCv2.jar (requires the Java runtime environment) from C:/Multitouch/Clients/flosc. And press the “start” button on the window that pops up. This program simply allows flash programs to access OSC data. This also has to be run every time you run multi-touch flash apps.
With that done, we were finally ready to try out the whole array of apps that have been written for DIY multi-touch tables. There aren’t a ton of apps available right, but we were able to find enough to have a good time with the table. Some apps come with Touchlib, in the C:/Multitouch/Clients folder, and we also recommend the AudioTouch apps, available at Seth Sandler's blog and the Multitouch Media App, by Laurence Muller.
Comments are closed on this article
AnitaG
August 07, 2011 at 1:50pm
Is there a youtube video that shows this being put together? It would really help to show the steps. Thanks!
chimney_pipe
August 03, 2011 at 12:26pm
This is super cool! I've always wanted a multitouch computer, but I figured it would cost me thousands of dollars if I were to ever get one. Thanks so much for this!
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Fred Ros
July 31, 2011 at 11:22am
This is astoundingly cool! My jaw dropped so much while watching the video. You guys are genius in building this Multitouch Surface Computer. Just wanna ask if it will work in making music? and whatever happened to this innovative invention? free chat rooms no registration
Good Vibes
July 30, 2011 at 1:09am
Wow, this is a really cool stuff! I am going to bookmark this link so that I can get back to this later and let some of my really techy friends to check on this site! Thanks for this guys.
CodyFish
July 29, 2011 at 9:27pm
Genius! This could be a candidate for an iPad killer. Well done! Detailed and easy to understand. Can you do something about the video though? I just want to watch how you guys did it and who knows, I mihgt try doing one pretty soon. international teaching jobs
bestjr73
July 29, 2011 at 7:15am
You just took away my drowsiness. Finally, I've stumbled upon a very enticing post, a multitouch surface computer. I can't wait to lay hands on it, I wonder how it feels like. I usually try to update myself with the latest trends in technology, I'm more like of a gadget guy. Thanks for this, very informative! free myspace layouts
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April 25, 2011 at 2:37am
can you also use this with program such as mozila firefox and windows internet explorer?
pragnesh
April 10, 2011 at 11:01pm
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.
jonnyboy
March 25, 2011 at 10:36am
Thanks for this, I've always wondered how they did multitouch. I think I'm a little out of my depth on this one though :( custom tents caravan canopy pop up canopies party tents canopy
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March 20, 2011 at 2:15am
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Propane
February 10, 2011 at 8:01am
Can you please post pictures of the inside of the cabinet with the camera and project installed?
I am doing a similar build for a school electronics project and would like a little more information on this part.
Propane
February 10, 2011 at 8:01am
Can you please post pictures of the inside of the cabinet with the camera and project installed?
I am doing a similar build for a school electronics project and would like a little more information on this part.
Propane
February 10, 2011 at 8:01am
Can you please post pictures of the inside of the cabinet with the camera and project installed?
I am doing a similar build for a school electronics project and would like a little more information on this part.
WAFFLELORD
January 21, 2011 at 11:23pm
Hey guys this really cool!! But could you give me a parts list? And possibly how much this costs to make? It would be really helpfull! Thanks!
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January 19, 2011 at 11:36pm
After ted,this is the one i am looking in to,..i strongly believe pranav mistry is the main source for this to happen,..he showed off to the entire world,.now people are coming up with the new names,..although this s a good achievement i can say,..but pranav was the first man to implement this method on the earth,..
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June 09, 2011 at 12:42am
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koool.vaibhav
January 09, 2011 at 3:19am
hi alex ...
please post some snaps of the complete setup inside the wooden cube ... it will be really helpful in visualzing the idea .. thanks ..
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inter4522
December 15, 2010 at 8:07pm
I did not know that you could build something like this. There is definitely a lot detail here that needs to be covered. Keep up the good work.
GAME2010
November 30, 2010 at 9:16am
i really appreciate your work and thanks a lot for it...i was just thinking weather we can use some other camera instead of ps3 camera...i have Enter 12MP camera..will it work??
maureenlee
January 06, 2011 at 2:14am
Wow! This is super nice! Hoping I could get or even build one so I can try if it will work for me. This will be super fun to use when me and my classmates would be writing research papers. Not sure though if we''ll ever finish one while using this fun gadget.
foter
July 25, 2011 at 4:43am
Do you have any idea how this work again now. I dont see any thing related to test inside can you please double check?
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October 27, 2010 at 5:48am
What we found that surprised us the most wasn’t anything about the future of multitouch; it was about something that people are doing right now. Replica Watches UK
mlody
October 22, 2010 at 12:43am
Hi,
I've got a real problem cause I've no idea why when I'm touching my screen fingers doesn't appear. Eye works properly beacuse when I move it to look on the LED it appears on the screen. I've covered acrylic with vellum an silicone. Any ideas?
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petersonvictor
October 07, 2010 at 3:28am
I was just wondering what assignment writing the white wires on pages 1&2 which seem to be attaching the led chain together are for and assignment help what way to put them together.
tornato7
August 17, 2010 at 5:13pm
Great info on building this, and i am attempting to, but i can't get the darn IR filter out of the PS3 eye lens. I might have a newer ps3 eye? where can i get the old ones? Thanks!
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lowqiumei
May 13, 2010 at 11:53pm
I am having some problem with the camera's orientation. My LED calibration everything was perfect and alright. But i am having some problem with the camera image orientation. When i open the "demo_smoke" application, after doing my calibration, when i touch on the left on my acrylic, on my laptop it shows that i am touching on the right, how can i flip it?
JuliaDee
February 18, 2010 at 7:46am
Instead of soldering all those LED's you can just wire-wrap directly to the LED leads (assuming they're square or rectangular in cross-section. I wouldn't recommend a hand-wrapping tool, you want an AC-powered gun, or if you can't afford that, a battery-op one. Mouser sells the wire and I think the tools as well. Wirewrap has been around for 40 years and is a great technique but unfortunately has become a bit of a "lost art" in this era of CAD and fast-turnaround PCB service houses.
touch screen mate
February 18, 2010 at 8:29am
Do you know what the wires are for tho what is there aim?
dgjames
March 23, 2010 at 3:22pm
It appears that the wires are used to connect the LED chains to the 12v bus on the PC power supply
touch screen mate
February 17, 2010 at 11:41am
Hi guys,
im excited at the prospect of making this for my epq on touch screen technology!
I was just wondering what the white wires on pages 1&2 which seem to be attaching the led chain together are for and what way to put them together.
Thanks!
PLEASE HELP =)
jersten
February 01, 2010 at 10:29pm
ok so i am interested in building one and certainly going to start soon as i kinda know what im doing haha but when i get to the computer part, if i use a regular desktop computer from dell...will i be able to operate the regular windows applications like browse the internet and click on the desktop icons and stuff like you would be able to with a mouse or in order to do this do i need to do something special with the table?
SCPRedMage
February 04, 2010 at 5:19pm
The system Maximum PC built did not support using multitouch to interact with normal applications, because at the time, there wasn't any software available to pass TouchLib's data over to Windows.
Of course, time makes all things possible: http://multitouchvista.codeplex.com/
