Posts Tagged ‘multitouch’

MT Update – Table Body

December 29, 2008

I was able to go to Lowe’s today – picked up all the wood I need to build my table’s body.  I don’t have a very good saw, so I just used the cutting center there. The guy who helped me out was great – he suggested I just go with regular plywood and 2x4s – not to pay more for MDF or something like that. I took my sketchup model printouts with lots of measurements, and I got done pretty fast. Four legs, four ‘legs’ for the base, four panels for the side, and a top and a bottom. I used 1/2″ thick wood, and 2″ square legs. Feel free to leave a comment here if you want the sketchup model I used – or just look through the several that I attached in the previous post through rapidshare.

For the top, rather than build a frame with 4 pieces, he suggested I use a jigsaw to cut the middle portion out, so I picked up a cheap $25 jigsaw, along with the necessary blades. I got it all picked out and cut in less than an hour, so I’m pretty proud of myself, having done no more than very small wood working projects before 🙂

Planning to build this week, with pictures! Then I can disassemble my LCD…



December 21, 2008

Haven’t posted in a couple of weeks…lots of action on the multitouch front, and not.

My monitor came in the mail. I started to disassemble it – just unscrewed a couple of screws and started to pry off the casing. I was talking to someone [Bridger Maxwell] about the monitor disassembly, and he told me that it was  a good idea to have your table and monitor mount 100% ready when you disassemble, so you can plant the monitor in its spot and never touch it again – the more you move it, the more likely you are to get dead lines/pixels, or break it.

So, I’ve been making sketchup models of what my box is going to look like – I’m going with a wooden frame, covered with MDF. One of my friends gave me a great idea regarding how to mount the LCD:ideaoverlay . That’s a very rough sketch, but you get the idea – I was going to use a dremel, etc., but this is so much simpler – the bottom piece would obviously be much smaller than the pic, of course.

I’ve done a bunch of sketchup models, for the various possibilities – 3/4″ thick wood, 1/2″ thick wood, with a lower frame, without a lower frame…here are all of them, from rapidshare [[UPDATE: NEW LINKS]]:

It’s winter break right now, so I’m hoping I get a chance to go to Home Depot/Lowe’s and pick up some wood. Itching to take my monitor apart 🙂

Getting a monitor!

December 2, 2008

Just won a monitor off of eBay! Yay!

Its the Acer AL1916W (19″) – nice discount, too. Much thanks to Bridger Maxwell for recommendation ( Can’t wait for it to come so I can RIP IT APART!

Yes! Will definitely post full disassembly pics when it comes in the mail.

Any advice on taking apart LCDs would be welcome and much appreciated (so I don’t kill it…)!


Diagramming Setup – Hardware

October 12, 2008

I’ve been piecing together parts and the overall building of the table in my mind for the last week or two, and I’ve been collecting some of the low-budget materials. As I mentioned earlier, I have an 18″ LCD (Sony SDM-S81) that is in (sort of) working condition. I still need to work out the details of the body and FTIR frame, so, to help me think through some of that, I quickly drew up a multi-faceted diagram by hand…not particularly neat or well-organized, but I scanned it in anyway. It includes very rough sketches of how things will be laid out in the table, and also parts+suppliers I need. Quite detailed…click on pic to zoom in.

Feedback on my plan is much appreciated and needed! 🙂 Thanks!

Attached here as JPEG and PDF…(not sure why I need multiple file formats…but here they are anyways)


MT Update

September 14, 2008

As I said previously, I’ve been playing around with lighting for my MTmini…angled light=bad shadows, too much light=washed out, not enough light=no blobs…I found that using lights that are angled upwards and reflect off the ceiling tend to work the best-fairly bright lights, but angled completely away from the device. Shining light directly down upon it doesn’t work too badly either, but like angled lights, your entire finger (as opposed to just your fingertips), are shadowed more than if indirect lights were used. SmokeDemo works like a charm for me now, nice accurate smokes.

Of course, with a larger scale setup, lights would need to be inside the actual device, for Rear DI and FTIR.

I found some nice LCD schematics here: | How CRT and LCD monitors work and here: 8512143_LCD_Disassembly_Gde.pdf (application/pdf Object) . Coupled with some guidance I found on several blogs, I think I have enough info on disassembling my LCD monitor, which I should be able to start taking apart shortly. I will most probably be using an old Sony LCD monitor, specifically the SDM-S81 (18″). It is partially working…its having some issues…it blinks off and on every minute or two, but for now, that’s not a problem.


August 12, 2008

Hello all!

Recently, I decided to begin working on a multi touch project, inspired by many, particulary Jeff Han, Bridger Maxwell, and other NUIGroup members. Essentially, there are two approaches to multi touch: FTIR (frustrated total internal reflection), and DI (diffused illumination). These techniques are explained well in the NUIGroup Wiki, here. Before embarking on a rather large scale, expensive project, I wanted a smaller scale, basic, proof-of-concept type example to create. I found this in Seth Sandler‘s MTmini. The MTmini is essentially a very basic form of front DI, composed of no more than a webcam, cardboard box, glass/acrylic, and a few sheets of paper.

How it works: the webcam goes in the cardboard box, the glass on top. The webcam is plugged into your computer, and when you press down on the glass, your fingers create shadows. The webcam picks these up, relays it to software that can comprehend these blobs on the glass (for example, TouchLib), and then TouchLib sends the data to an application which uses the touch event.

It seemed simple enough, and after a quick trip to Home Depot, I had everything I needed, and literally, in 5 minutes, I was done with the hardware. Now, for the software-TouchLib. From the NUIGroup website, I downloaded the latest version of TouchLib (2.0). From this point on, I had a bit of trouble with various components. I ran config.bat, as the instructions said to, which was fine, but with the MTmini, with no display, it was rather difficult to calibrate. Anyways, I was ready to try to run some applications, but I found that it wasn’t all that simple. Running TouchLib successfully requires among other things, .Net 2.0 framework (which in turn requires Windows XP SP2, which requires Windows Update 3.0, which requires Windows Genuine Advantage Tool….). After I was done with these downloads, I ran into some more trouble as I found that in order to run Flash-based apps, which the demos are, I needed FLOSC, and JRE 1.6. Several other multi touch users helped me out at nuigroup’s irc channel ( #nuigroup) to help me get to a working MTmini setup, so much thanks to them. Nuiman explains the need for FLOSC/OSC very well:

1) The TUIO (OSC) data is SENT from Touchlib’s “osc.exe”.

2) The FLOSC gateway CONVERTS the OSC (UDP) data into XML (TCP)

3) The Flash client uses an XMLSocket to RECEIVE and parse the XML data then renders the cursors within your application.”

This is necessary because Flash cannot understand UDP data.

Anyways, I downloaded a whole bunch of things (more details later), and I was able to run Flash apps-basically, I should’ve downloaded this package, and I wouldn’t have had the problems I was having, because cerupcat, the user who designed MTmini, had a special package for those using it, as it needed certain filters. Two .bat files downloaded with that package (similar to the TouchLib files I downloaded earlier), took the place of the FLOSC and OSC applications that I previously needed to run to have Flash apps recognize touch events.

So….now, my MTmini is in pretty good shape, and I am trying to fine tune the calibration of it, as the touches are not very accurate right now, and I am also trying to find ways to improve the hardware-better lighting, better webcam, etc. Software, of course, is a big part of it, and I am starting to learn to program in C++ in order to program applications for my multi touch device. Eventually, I plan to move past MTmini, and design and build a larger-scale, more stable, preferably FTIR multi touch table. But for now, I plan to work more with the software, and do what I can with MTmini.

Pictures of my MTmini setup coming soon!