DSI Multitouch construction – Part 8

In the never ending quest to get better blob tracking on my touch screen I decided to add more cameras. A few months ago I added a second camera but they didn’t quite cover the whole screen – there was about an inch gap in the centre of the screen. I didn’t want to use wider lenses because of the distortion so I decided to add two more camera to bring the total to 4, with each camera tracking a quarter of the screen.

I was trying to think of a good way to mount the cameras so that they were evenly spaced and I came up with the idea of using a piece of wood with a routed cavity to sit each camera in. The problem with this was that the wood would have to sit above the backlight of the LCD and so it would block some light. Then I remembered I had a spare piece of 10mm acrylic from my old 19″  FTIR touch screen. So instead of using wood I cut and routed the piece of acrylic so that the cameras had transparent mounting plates.

Here are some photos of my process…

Left: Acrylic measured so that the lense of each camera is perfectly spaced; Right: Testing routing the acrylic – I had to use the slowest speed and keep moving so the router bit didn’t gum up with melted plastic. Super messy!


DSI Multitouch construction – Part 7

Well its been a while since I posted an update on my DSI coffee table. It is pretty much complete now. The last thing I have to do is get a piece of scratch resistant plexiglas for the table top to create a single seamless top. I would also like to get black perspex for the sides so the table has a piano black finish, but this is a maybe in the future. The reason I have been holding off with the final top piece is because I am still experimenting with different lighting so blobs can be detected through the extra layer of plastic. Currently I am waiting on a second PS3 Eye camera so I can try a two camera setup to hopefully get clearer and less distorted images for tracking.


DSI Multitouch construction – Part 6

Here is a small update on the current state of my coffee table. Its been a nearly a year now since I first started and I’m still slowly working on it. Recently I decided to add some touch sensitive hardware buttons at the edge of the screen. I researched some different ways of doing this and I decided to use Phidgets since these seem to be the easiest to use with Flash or any other languages and weren’t as low level as something like Arduino. So I bought a Phidgets board and 4 touch sensors and installed two on each side of the screen to be used as hardware buttons. I have adjusted my multitouch painting application so that these buttons hide/show tools, layers and other panels. Here are some photos of the installation in the table top:

Routing out the recesses in the table top to sit the sensors in:

Mounting the Phidgets controller:

Two of the Phidgets touch sensors sitting in place. They will be covered by 3mm of perspex which will eventually be the top layer of the table:

DSI Multitouch construction – Part 5

Here is some more updated photos of the coffee table. I wanted to post some shots up before I head over to Japan in a few days. I managed to get it out of my bedroom and into the lounge for some better shots. Note that the top and sides are not the final. Currently they are MDF painted matte black, but when I get back from overseas in a month I will replace the top and sides with gloss black perspex so it’s all shiney! Check out the new photos below.

With the temporary top and sides on:

Sides off, showing the PC and LCD components:

Height comparison – the whole unit is about 500mm height, with the inner height between camera and lcd about 45cm.

Top off, showing the IR LEDs etc.

DSI Multitouch construction – Part 4.5

This is just a small update with a few new photos… I’ve have now painted the table top black, I used a matte black spray paint (because I think its easier to get an even colour with) and then went over the top with a clear gloss. A also made a temporary top cover and painted it black also, eventualy this will either be gloss black perspex or I had an idea of having a clear frame and putting interchangeable frame designs on paper under it.

Preparing for paint.

Undercoat – 1 can of white primer

Black – 1 can of matte black, 1 can of Clear coat

An early version on my multitouch paint app.

Here are some more demo videos form my MT painting app…

Spray Paint with a spray can controller i made.

Painting and paint mixing using a paint brush.

DSI Multitouch construction – Part 4

Its been a while since I posted an update on my Multitouch coffee table. I am still working on it, just little bits at a time so no significant progress has been made worth posting. But here are some more photos of the progress. I will have some more recent shots up later in the week.

Testing diffusers for the LCD, the ones that came with the screen were too tick and blurred the blobs/fiducials too much. I decided to go with tracing paper which works really well as you can see in the image below.

Installing Windows 7…

Since I couldn’t be bothered pulling everything apart to paint the inside white, instead I lined the inside with white printer paper. I placed the original diffusers directly on top the back light to diffuse it more without affecting the blobs.


I bought a smart powerboard to hook everything up inside the box, this way everything including the LCD, amplifier and any other components have their power switched off when the PC is switched off. When the PC turns on, the powerboard detects the change in current and switches all the other sockets on. This way everything can be powered on by a single push button.


All circuitry, speakers and wires are now mounted…


View from the top looking at the back light without the back light diffuser

More photos coming soon…
Here are some dodgey videos taken on my phone…

Plants vs Zombies:

Fish pond screensaver from the Win 7 Touch Pack:

Basically all thats left now is to order black perspex for the outer box so the whole unit is shiny and black.

DSI Multitouch construction – Part 3

Over the weekend I made a lot more progress on my multitouch coffee table. I also discovered some issues – firstly the original backlight emits way too much infra-red light so I am going to have to make a custom one out of ultra-bright LED strips, and secondly I don’t seem to be getting any blobs when placing a layer of glass or clear acrylic above the Endlighten. I get great blobs when touching the Endlighten directly, but I want to avoid this since it scratches easily.  More photos below.

Gluing and soldering the IR LEDs into aluminum rails… all 96 of them

The box so far

The power ‘terminal’ for the backlight, and the CCFL tubes in the bottom of the box

All the TV circuitry temporarily mounted in place, all the placement turned out great… the FFC cables brought no issues at all!

TV turned on… here I have no diffuser behind the LCD so you can clearly see the back light and the inside of the box

PS3 Camera poking through back light

Wiring the LEDs

Mounting PC parts –

  • MB: Asus P5E-Deluxe
  • CPU: Core2 Quad 2.8Ghz
  • RAM: 4GB 1066 DDR2
  • PSU: Coolmaster 460w
  • Graphics: Radeon 3850 (I think, though not pictured here)

DSI Multitouch construction – Part 2

Here are some more shots of the work in progress of the DSI Multitouch Coffee table I’m building. Last week the Endlighten arrived. This wasn’t the easiest to acquire – in Australia the only option really was to buy a full sheet which would have cost $1000+. The best place to get cut-to-size acrylic is through the Evonik Online Store. Unfortunately they don’t ship outside the US so I had to get an account set up at MyUS, which provides a US mailing address with package forwarding so I could order the Acrylic to this address then have it forward to my address. This turned out to be the cheapest option (I also looked into some other methods).

The package was packed pretty well with a wooden frame for protection:

Placing the Endlighten on the LCD with the aluminium LED rails sitting in place. A final layer of glass/abrasion resistant acrylic will sit flush on top, providing a seamless full glass top:

Shot from underneath showing standard clear acrylic (3mm thick from Bunnings) supporting the backlight light diffuser layers from the LCD:

Some more shots of the clear acrylic with the diffusers. The LCD originally had 4 diffusing layers, but I will probably only use the two ‘frosted’ ones. I might place the Fresnal layers directly on top the back light which will be sitting at the base of the unit.

32″ DSI Multitouch coffee table construction – Part 1

For a while now I have been planning a 32″ multitouch coffee table. DSI uses a special acrylic which when lit from the edges distrubutes even illumination across the panel. Over the last few weeks I have been collecting bits and pieces and this weekend I started making the top for the table. Photos below.

The TV I will be using – 32″ Full HD Samsung LCD

TV with the back casing removed

FFC cables could be a problem

Hopefully this long ribbon cable will allow me to use the original FFC cables

The LCD panel removed

The backlight

The CCFL tubes in the backlight… Looks like I will have to make a custom backlight

I decided to make the table top out of 3 sheets of MDF glued together

Lining the sheets up

Checking that the LCD fits

Glueing sheets togther