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Sunday, May 11, 2008

How I built ORION mt

The ORION mt table has been one of the smoothest/responsive DI (Diffused Illumination) tables that I have built. Below is a video of the ORION mt in it's prototype state.

You can view the original post on the NuiGroup forum here

Please see the Showcase post on Nui Group forums here:



Here is a short explanation on how it was built.

Rear Diffused Illumination: DI - The Theory:

Infrared light is shined at the screen from below the touch surface from. A diffuser is placed on the bottom of the touch surface. When an object touches the surface it reflects more light than the diffuser or objects in the background. The extra light is sensed by an Infrared camera. Below are pictures illustrating the effect of DI and also a screenshot an image captured by the camera.





The above images and text have been extracted from the NUI Group wiki

The Box:
Made out of 12mm craft wood (MDF), the box is 710mm(w) x 775mm(l) x 655mm(h). I left a section on the top of the box so that I could mount a small mirror to increase projection throw.



The Projector:
For the projection I'm using a SHARP DLP projector Model: PGM15S


Table Specs:
My PC is an AMD Athlon 64X2 Dual Core 3600+ with 2GHz RAM, Nvidia GeForce 7600gt Graphics Card. Sharp PG-M15S projector, Frosted Glass as diffuser/projection/surface.

The resolution that I am using is 1024x768 (DVI to DVI).

WebCam Specs:


The camera is an Xbox Vision 360 (AUD$50) (I’m using 320x240 res @ 60fps)
This camera was fairly easy to modify the IR filter.

Also our friends Jose & Vasco (jmccd) from NUI Group have summarized our posts on the forum and made a pdf guide which you can download here

See the original NuiGroup post here

IR Illuminators:


In the ORION mt there are 3 illiminators. I’ve drawn up a crappy picture in MS Paint to show the layout of the illuminators. (1x 140 IR Leds, 1x 80 IR Leds and a smaller 45 Led illuminator too!)

Illuminator number 1 is the 140 IR led I got from a mate. Number 2 is the 80 IR Led I made up, and Number 3 is the 45 Led one.
The purple border represents the physical screen projection size in relation to the illuminators and the box.

The need for more IR light was due to the fact that during the day or close to a IR light source (overhead lights or the sun) the IR that I was generating was not enough to receive clear blobs.

WebCam & Projector Placement:
Here are some pictures to illustrate the camera, mirror and projector placements in the ORIONmt. I originally had a camera angle issue where i wanted to place the camera in the middle of the floor facing upwards, however I could not capture the entire screen. To overcome this, I ended up moving the camera to reflect of the 2nd mirror. That way I can capture the entire screen (with overscan)

See below:



I have also added a beamer/mirror placement applet that may help with design of your own multi-touch display.

Please see below:

Beamer/Mirror Placement Guide Applet




IR Illuminators - detail
The 140IR LED Illuminator was originally bought by my mate from ebay, and I found one similar on ebay (after typing in the search bar of ebay "140 IR Led"), so here are some specs on it.



- Built-in sensor (which I taped over)

- Illuminating range: Detecting range is 80m, viewing range is 60m (outdoor)

- Definition Consumed power: 18W

- Wave length : 850nM

- Structure: All weather aluminum and reinforced glass

- Power: DC 12V 1000mA

Because of the narrow beam of this IR illuminator, I was getting a large hotspot on the glass. To get around this, I have angled the 140 IR Illuminator so that the light is emitted and reflected off the side wall of the box. (please see above pics)

Also, the placement of the illuminators can be seen in the picture below...



Glass Specs
The sheet of glass is 4mm thick, 71cmx56cm frosted (sandblasted) on one side for the diffuser/projection surface. It was bought from a glass manufacturer, cut to size while I waited and cost about AUD$40-50.

I will add photos soon...

More soon....

17 comments:

iProbo said...

Hi!

Great work!

Did you apply an special tratment to the screen? I mean, silicon or anything like that?

Would you please specify the IR iluminators models?

Thank you!

Paul D'Intino said...

Hey there,

Thanks for the kind words,

Because the screen is using the DI method, there is no compliant surface needed (silicone etc..)

Just an ordinary piece of frosted glass will do the trick.

I have updated my blog with the answers to your questions, however, the IR illuminator (140IR Led) was originally bought by a mate from ebay.

Please see the blog for more detail/specs etc.

Cheers,
Paul

Anonymous said...

Incredible work!
Will you add more pics of you mtd? I'd love to see more of you work. And could you write more about your pc components you used for the project? A last question: How high is the temperature aorund the beamer and the other components? Did you need to elaborate a cooling system?

Paul D'Intino said...

Hi there, thank you for your comments. Yes there will be more pics soon (new table design is underway. What other PC specifications were you after that I haven't listed? Anything specific? Also yes, the box does get hot and I'm not running any fans at this stage. (nothing too serious) So the new box design will have allocations for 2 fans at this stage.

David said...

Hey Paul,

first things first... You RoCk!

Would it be possible if you can upload a picture of the way you've placed the 3 led illuminators? i mean, like the pictures you posted for Camera placement and Projector placement.
Thanks a tonne bro...
again,
You rock... lol

Paul D'Intino said...

Haha! Thanks for the comments David.

I ahave uploaded an image of the illumination used in ORIONmt. The picture is very busy and probably makes no sense, but it might give you an idea on how I am achieving all round illumination.

David said...

WoW,
I guess this the only 'request comment' I have posted in which the answer and work has been done in not less than half a day.
Thanks a lot Paul. The pictures have helped me a great deal.

Am, sorry... but I have yet another request... :D (another picture)...

Can you like just make a simple sketch diagram showing the whole working or principle or theory or whatever they call it. I do know that many have made sketches n' all about this... but I find the pictures of yours to be extremely helpful, you make it so easy to understand.
Thanks again...
David

SIGNATURE while posting comments on Paul's blog:
YOU ROCK.

Paul D'Intino said...

Hey David, thanks! =)

I've added a "Theory" section with text and some pictures. Please let me know if it answers your question.

It's not a simple MS Paint drawing but it outlines the process.

Thanks again for the comments =)

David said...

Hey Paul,

Thanks for the super quick reply, as usual!

This has solved most of my doubts on DI.
A small doubt, should the diffuser material be placed in such a way that when we touch the surface, we touch the material... or should it be on the other side of the surface glass (the 'non-touching' side)?

And, what material have you used as a diffuser for your ORIONmt?

Thanks...

-Signature:--------
YOU ROCK. :D

David said...

Oh, sorry, never mind... Just read the glass specs

Fernandoka said...

nice work!!
wondering where u purchased the ir-lamps?

ty!!

F/

Paul D'Intino said...

Hey fernandoka,

Thanks for the comments!

The 140 IR Led illuminator was bought off a friend of mine but originally it was purchased from ebay. (type in 140 IR led in ebay search bar)The other IR illuminators I actually made using a printed circuit board and IR Leds.

If you are considering building a table with similar dimensions to mine, my recommendation would be to go with maybe 4 x 48 IR Led Illuminators for a much more even distribution of IR light.

Uwe said...

Hi,

great work...but is it safe? Is the diffuser strong enough to prevent this strong IR light getting into the eyes of the user?
Even if it is invisible it can harm your eyes...did you care about that?

Greetings,
Uwe

Paul D'Intino said...

Hello Uwe,

Please read this post:

http://nuigroup.com/forums/viewthread/2102/

Here is a quote from this post...

"..The sun itself puts out an incredible amount more IR light than what we are. There really shouldn’t be any harm in using IR for our purpose. We’re not putting anything near what’s already out there by the sun, light bulbs, etc.

Also, in each MT technique, none of the light is coming you without being diffused or scattered in some way..

jsearles said...

Paul, first of all congratulations on a gr8 table, a gr8 blog and some gr8 software. I have been following nuigroup for about 2 months now and am just getting around to reading your blog.

I just finished an LLP table except for some finetuning th elaser placements it's working ok. Could you confirm the advantages of using a faster FPS camera. I am getting only 30fps from a Philips SPC900NC, but ai have a Sont PS3 ready to go. I just want to be clear on what to expect.

You have also convinced me to start on my next table and make it a DI. With fiducial capability, it's got to be a winner.
John
nuigroup:Jsearles

Paul D'Intino said...

Hey John, Thanks for the kind words... I'm happy that people are using my apps and find the info on NUIGroup and on my blog helpful..

With the Camera, The idea is to get a high frame per second camera (and a pretty decent computer to run the apps) which will reduce the lag from the user’s interaction and the camera/computer processing time.
Many people are using the PS3 camera because it is a cheap, 640x480 @ 60fps/75fps (and 320x240 @ 120fps!)camera which is still USB.

I would recommend using a faster FPS camera if you want a more realistic and smoother setup.

Cheers
-Paul

Nicolino said...

great project!
we are also working on our multitouch table.
Very inspiring

thank you very much

limulo