Hi to all,

i am new in this MT stuff, but i made some research and succesfully done a few tests with the “simple” methods like the MTmini etc. I have an MT project on start and i would like to ask for some oppinions since i am in the process to build a serious prototype. We will build a MT-table for one of our clients. The table would be used on fairs/booths with some simple applications (nothing special, just as simple like the picture viewer/mm-demo apps written in flash).

I am planning to go with rear DI with some IR-sources behind the projection plate. The projection on the table will be appr. 60’’. Since the table will be used as a “real” table, we decided to use a glass material (i don’t know the right terminology in english but the glass is satined on one side from the factory - sand blasted or etched?). I hope to get the test plate today or tomorrow, so we can do some projection testings. Do you have any experiences with glass plates (without a special compliant surface)?

For testings we are using currently a modded Xbox camera, but a fire-i is on the way for the “release candidate”. Since we are try to stay completly on OSX, it seems for me the better choice over the firefly (driver for OSX etc.).

As a projector we are thinking about to use the Sanyo PLC-XL50. I konw the resolution is only 1.024 x 768, but this should be sufficient - is this sufficient? What do you mean?. The main reason why we are considering the Sanyo is that we don’t have to mess around with mirrors for the projection, since the very small throw distance and the possibility to mount the projector verticaly. But maybe you can give me some advice with other/better projectors?

As i mentioned we would like to “sty” completly on OSX. So i am very exited to see what the new LUX framework will bring us! And as we are at this point: are there any news regarding LUX? Would be great to hear something from - i have sent a mail to last week but did not get an answer till now… Is there somebody in the community who could compile a working touchlib version for OSX an could share the bin? So i could do some testings in OSX and not in Windows?

So that’s all for now.

Thank you in advance for your answers/advices, i will post my experiences here…

I think if you’re doing DI you don’t have to worry as much about a “compliant surface” like you do with FTIR.  Mostly you’ll need to make sure you have the proper diffusion.

I too am making a Mac OS X based multi-touch table and Lux is looking incredible.  Look here for status on Lux: http://nuigroup.com/forums/viewthread/2299/ Seems to be any day now once some final issues are worked out with the current beta.  Keeping my fingers crossed

Hi sandor,

yo wieder mal ein deutscher am start

You could also try to build a DSI (Diffused Surface Illumination) setup, which is basically a DI setup using a special acrylic. And since you live
in Germany, its easy to order there (the acrylic)… Its pretty simple and you don`t have to worry about getting the IR light diffuesed evenly…

I made a post on my blog: http://iad.projects.zhdk.ch/multitouch/?p=90

@ Ignigena: sorry - you are right with the compiant surface. I was actualy talking about the right “projection” surface. I hope that the sandblasted side will do the job… Godd to see that i am not the only Mac user here Let’s see what LUX will bring…

@ YO Tim! Nice to hear from you. I guess is too late for a friedly “Hopp Schwitz” I have allready read about your work - awsome man! And a realy great idea with that DSI setup. My main reason to go with rear DI is that i HAVE to use glass instead of acrylic - it’s not a good idea to make a conference table for a fair out of acrylic After a day your surface is completly scratched… Maybe this could be solved with a protection layer of thinner glass above the acrylic, but for this project i do not have too much time for experimenting. As i said - i am a completly beginner, but far as i can see rear DI seems to be the fastest way. I looked over the availabel “real live” examples ( surface, that awsome table for Abu Dhabi, reactable etc.) and they all seems to use rear DI… THX again! Good to know that ther’s a real expert in my naigborhood

hey sandro,

i am actually german, so i did have a good time at the euro anyway.. to bad about the swiss team though, they are my second favorite of course

About DSI… basically its the same as DI, but takes some work at the beginning since you have to build a led frame. But in the end, it will save you time
because you don` t have to worry about the even illumination. I mean, DI sounds pretty simple, but finetuning takes a long, long time. If you don`t get
the light even, you will have problems with correct recognition of the fingers. So one part of the screen is oversensitive (reacts before touching), while you really
have to press hard on the other side.. DSI does not have that problem, since the light is even from the beginning, and all parts react the same. If you are on
a tight timeframe and its your first setup, I would recommend it..

You can put a thin sheet of protective glass on top of the plexi/screen combination. It still works, I tested it already..

I’d have to second what Tim said. DSI is really my favorite technique right now although I haven’t had a chance to test it. Sandor, keep in mind that MS surface and reactable are using DI because they use fiducial (symbol) detection and physical objects, not just fingers. If you only need fingers, then FTIR is the way to go in my opinion. Well, that was until DSI came along which I think is really a good mix of the two.

Yo Guys!

Thanks for the feedbach. Well i quess that i will try out both ways since my materials for DI (IR-illuminators and glass plate) are allready there… Tim, ist there a special angle for mounting the LEDs used in the DSI method (like in other FTIR solutions)? Did you also checked out the PLEXIGLAS® XT Grau 99561 RP - since this is also from the same supplyer and has some nice specifications?

Right now i’m quite frustrated: i was fighting during the whole day with that Xbox camera! I’m using windows XP64 on my MacPro and installing that Microsoft! camera is a nightmare! No driver etc. Finaly i’v got the cam working but no chance to use it in touchlib… I followed the instructions by giving a “friendly_name” in the xml-file but no chance! I quess the problem is that the cam installs as a “USB Video Device” and not as “Xbox whatever"… Any clue somebody?

Jesus guys! When is finaly an OSX touchlib/lux/opentouch installer available. I’m tyred of this MS-S*****

Thanks for helping again. Will post my results (when i have some)…

Cheers!

hi sandro…

first of all, get a good cam! Well haven`t tried the xbox one, but I used the phillips spc one… and it sucked. Firewire is he way to go,
at least the unibrain.

I myself work on mac, and I am still frustrated that there is no good software yet.. they are coming though! For now, I use the wiimoteWhiteboard software,
which also sends TUIO Messages and works on osx. So I develop apps (Flash AS3) on osx, and when I am ready or satisfied I reboot into windows and
use touchlib…

BTW, I am building a DSI setup for myself at home, so I will be posting some more step by step info soon, I`ll let you know..

Yo Tim,

sure man - the fire-i is on the way. Took a few days since i first was trying to get the camera from dr.bott, but they estimated 3-4 week of delivery time. Well after that i discovered that the apple shop is offering the fire-i also… BTW a lot cheaper than bott… So i hope that the fire-i is here tomorrow… I allready got a fisheye objective for M12 without IR filter - good supplyer btw. just got it and tested with the XBox crap - at least it fits well and gives a very good view at a very short distance… So it should work well with the unibrain.

I found also a supplyer they can provide me with pre-made IR rails ready to use (yeah, i know i’m lazy!!!). Gonna talk tomorrow with an acryl company for the plates - i guess i will go for both solutions (for FTIR and DSI)… Let’s see what will bring the best results (not that i would not trust your expertise!)

I have some important questions:

- did one of you guys tryed out to use a glass plate for FTIR? Or is this senseless?
- for you DSI setup - is there an angle for the LEDs needed?
- also for DSI: how thick was the glass-plate you used for protection??

BTW: you are confusing me now a bit. You say that you’r using the wiimoteWhiteboard for Mac-Developement… Are you using the software with a Camera??? Or with the WiiMote and some LED sources?

Cheers!

hey sandor,

- you cannot use glass on FTIR setups, it wont work (or very bad)
- check what kind of leds your guy is using, also the angle the radiate, kind of important (wide angle, 880 or 850 nm wavelength- check the SFH-485P from osram for specs..)
- I used 10mm endlighten for the DSI Setup, 8mm should work as well (depends on the size of the table though)

Just a tip… using wide angle lenses can lead into problems, because of the amout they distort. Also you will need good bandpassfilters because otherwise you will get a dark image
around the edges.. Hard to explain. Does not matter if you just use film negatives as a filter. Just don`t get thorlabs filters, they do not well with wide angle lenses. Tried it myself!

wiimote: well I use it for development on osx with a wiimote, not a camera. That way I can test apps quickly in my native system and when I am finished I boot windows and test it with a “normal” table. The wiimoteWhiteboard also sends TUIO messages, so my Flash apps work the same…

Hey Tim,

thank you for yor tipps man! Hope i don’t get you annoyed with my questions So i will leave the glass where it is As for the guys they are making the LED-stuff: will have a call tomorrow with them an see what tey can supply - at least they sound serious about what they are offering. Will report asap.

Endlighten: yeah - i will try that out with 10mm - but my question was about the glass plate you used ABOVE the endlighten to protect the surface… Or did i missunderstud something?

About the fisheye lens: yepp i know about the optical vooooooodoo with the dark edges… It’s a well-known prob with wide angles… Well i have to see what’s happening with the firewire cam and the phisical dimensions of our table. BTW: had today an interesting talk with some projector guys - they offered me to put us on a “project” basis by the projector manufacturers - so we can test out some nice projetors… Sounds good… But i have to wait till next week since the tech-guy is on holliday… Shit: my deadline is getting closer and closer )

WiiiMote: oh, ok. I was realy wondering… Did you actualy seen the project of Ben (BBtouch)? Looks very promissing. I have downloaded the source and compiled it without problems. Looks nice and runs on OSX… Well if he adds the TUIO and the ability to use some filters like invert/background removal/and pinch distorsion… well… i guess it will make a lot of fun… (and Ben is my hero in that case!)…

Thanks again man for the nice advice! If you don’t mind i will contact you on PM the next days?

Gruezzi!