First project : DSI - LCD Coffeetable
Posted: 30 July 2009 08:53 AM   [ Ignore ]
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I’ve started the project a couple of weeks ago but didn’t get the time to write anything about it yet.

Country of origin : Belgium
Type of Table: DSI
Screen Size: 22” 16:9 screen based on the LG W2242T LCD
Actual Table Dimensions: Coffee Table (or higher if required

Steps taken :

THE IR FRAME

- Soldered 80 IR LEDs

IR LEDs SPECS :

intensity typ. : 10mW/sr
viewing angle: 50°
wavelength (peak): 940nm
forward voltage: 1.2V
LED current (If): 20mA

- Inserted IR LEDs into drilled anodised “h” profiled aluminium rails
- Connected the whole frame to a computer power supply

THE LCD SCREEN (LG W2242T)

- Opened it up with the help of a small screwdriver to pop out the plastic case. The rest was quite easy as the backlight comes in one block. I may need to solder some extra wires in order to make the power cables longer. The LCD doesn’t seem to have any FFC problem, I would really recommand it for people wanting to try LCD methods for cheap prices (got my screen for around 120 €)

- Checked every element separatly. Backlight lights up just fine (it’s made of white leds around a piece of plexiglas + diffuser framed in metal. I’m still wondering if I should take the frame appart or not… The LCD also works perfectly

THE CAMERA

- Bought and received a 15€ PS2 Eye Toy. I just wanted to play around with it so I keep the PS3 version for later.
- Easily opened up the Eye Toy case (two screws to remove). The lens plastic cover was unclipped and the lens removed by unscrewing it. The IR filter was just a small additional glass maintainted by some plastic frame that I easily cut out with a small sharp cutter.
- Now I see what my IR leds are truly made of ! At first I was affraid that they wouldn’t be powerfull enough, now i feel a bit better (I have a video that i’ll post later) as the light travels up to my fingers even in the very center of the table. I still need to test it with the endlighten though

THE SOFTWARE

- Nothing much to say yet. I’ve installed everything needed to run CCV on Windows 7, tested out some demo’s but nothing really fancy as the table is not yet functionnal.

THE ENDLIGHTEN

- I’m still waiting to receive my order placed a few days ago for a 530 by 370 mm, 8mm thick endlighten ordered at Plexiglas-shop (price is around 58€, shipping included). I’ve been trying to find some reseller that could handle the polishing (or laser cutting) of a piece of acrylic. Unfortunatly, for the small quantity I needed, it was hard to get a decent price (and had to ring back several times in order to get a quote… sometimes customer service gets really poor in Belgium smile). So after talking with some people, I opted for the DIY solution....

- Bought 150, 240, 300 wet sandpaper + some extra polishing wheel for my driller for around 12€ (which means that it’s 2 times cheaper than getting it polished by some company + you learn something + it’s faster + you keeep the materials for later projects… No need to think about it twice !!!)

ACTUAL SITUATION

Well, that’s were i’m at at this moment. As you have probably noticed, I haven’t talked about the computer hardware, just because I’m planning on using a simple laptop for a start and once i figure out the config needed, I will probably buy separate computer parts or go for a “peripheral” approach (ie : keep the computer outside) as I want the lowest table possible.

Right now, I need to figure out how I am going to put all this together. Probably gonna do some 3D previz in order to figure out what’s working and what’s not. I saw some aluminium profiles that you could stick together using simple bolts and screws and build some modular structure to fix all the frames / screens / devices, but I couldn’t find any information on where to buy these.

Last thing I need to test is the distance from camera to endlighten. I’m gonna need a front surface mirror to bounce the image once in order to achieve low level for my table and I will have to figure out where to place that mirror.

I already have plenty of pictures and a couple of videos to show you but I am running out of time for today :p

Thanks for all the support offered by NUI Group members up to now. It’s been a delight to learn from you people smile

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Posted: 31 July 2009 02:52 AM   [ Ignore ]   [ # 1 ]
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Hey dimitri,

some suggestions:

1. buy more sandpaper with 800 an 1000 number and wet sand it with 1000.
2. do not use polishing wheel on the drill, it will burn the acrylic and melt it. do polishing by hand.

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My Blog: http://zviangi.blogspot.com with pictures and videos ....text in Georgian
22" LCD DSI coffee table
58" DI Table
FTIR table (my 1st) http://www.youtube.com/watch?v=mR90jjZNs8s

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Posted: 02 August 2009 05:20 AM   [ Ignore ]   [ # 2 ]
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and one more:

why did you choose 940nm leds?  and not 850nm?

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My Blog: http://zviangi.blogspot.com with pictures and videos ....text in Georgian
22" LCD DSI coffee table
58" DI Table
FTIR table (my 1st) http://www.youtube.com/watch?v=mR90jjZNs8s

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Posted: 02 August 2009 01:18 PM   [ Ignore ]   [ # 3 ]
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Total Posts:  40
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Just because I didn’t knew yet about which IR wavelength was better to use.... I’ll use 850 for next project or if the leds that I use right now or not strong enough.

By the way, i just received the endlighten two days ago. I’m gonna polish it tomorrow and see if my leds are good enough

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Posted: 11 August 2009 04:00 PM   [ Ignore ]   [ # 4 ]
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Today, I’ve finished a first major step into my first MT Table project. The whole setup is know “working” and by working I mean that everything is in place and I’ve managed to display and use all of the demos provided with CCV.

Although now I have a bunch of fixes to do in order to make the setup work better so please do advise....

Take a look at this video (which is unexpectedly fast… seems like VIMEO had a problem when compressing it) :

It shows some basic testing I’ve been going through. One thing I’m affraid is that my LEDS (940nm) won’t be powerful enough. On one side of the table, it detects them quite easily and not on the other. Don’t know what’s causing this…

A list of changes to be done :

- REPLACE the camera + mirror (to achieve low depth) WITH a camera + wide angle lens AND/OR add extra length to table feet. Check if M12 lenses are also compatible with PS2 Eyetoy

Why ? Because the distortion caused by an angled mirror is creating diverse problems :

It creates a gradient-like area that makes one end of the IR plane (the short one) less sensitive because it has less pixel definition to use (same blob will appear smaller on one end than on the other) and also because due to the angle, we are now able to see direct light from the leds and blocking this light would also block a great deal of the screen itself causing no blob detection in both cases (either because of too much light, or because of no light at all)

Watch the video if you need to understand what I’m talking about.

- Try to find a way to diffuse the light coming from the backlight screen just behind the LCD… (right now, when looking at the lcd from the side, i can barely see anything, because backlight is not right behind it)

- Find a way to prevent the backlight reflection from being seen by the camera (see video as well)

- Decide if LED’s are powerful enough or replace them with more powerful LEDS (850nm this time !)

- Buy some bandpass filters for either 940 or 850 nm (depending on the above) and check if they are compatible with a PS2 Eyetoy

- Ask about the LCD backlight to see if some parts of it should be removed or placed above the camera (see diffuser)

- Ask about another diffuser that would diffuse IR ambiant light and where it should be placed (between LCD and supporting glass ? or above endligthen and everything else ?

That’s all for the moment, please give me some feedback, it would be very VERY much appreciated as right now, I feel a little bit lost with all the amount of unknown data…

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