Tag Archive for 'Rear DI'

Rear DI Multi touch Set Up Part 2

With the camera set up in the previous part I proceeded to IKEA in search of a suitable cabinet which I found a perfect one that has an open top (Its supposed to be for the kitchen, but it fit the purpose of a multi touch anyways :) )

Here is the IKEA code for the cabinet I bought:
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The table with makeshift cardboard to hold the mini acrylic piece I got from Art Friends at Bras Basah Complex for around $8 SGD:
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The projector and materials in the cabinet, notice the cables running out from a small hole through the top, it was pretty convenient without having to manually drill a hole
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The first run of the initial set up:
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The blurry projection on about 40 pieces of laminating pockets as diffuser, acrylic at the bottom of those sheets
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Close up view from under the cabinet:
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In this iteration of the set up, there were basically loads of problems
- Hot spot from the IR illuminator
- Hot spot from the projector
- Floppy disk filter largely not effective (only discovered later on when the infrared cut filter arrived and made the magical difference)
- Double image from the standard mirror used (explained below)
- Lack of a proper holder to hold the mirror
- The laminating sheets were very poor diffusers

Explanation for double image:
In a standard mirror, there are two layers

| <- layer A | <- layer B

layer A is the glass layer and layer B is the reflective surface, because of refraction at the glass layer, some of the light slows and bends and causes another faint image to be projected beside the original image on the projection surface. The answer to this would be an industrial front surface mirror. These front surface mirrors are pretty fragile so special care has to be taken not to scratch its delicate surface.

Eventually the PS3 eye could not capture any blobs at all with the projector on. With the projector off, it was better and blobs could be registered. The PS3 eye is removed from its case and embedded in the makeshift Styrofoam holder (which is bad as I found out later on because the camera sat on the projector and the Styrofoam basically hits everything up a lot and caused the projector to overheat and shut down automatically after just 3 - 5 minutes)

These are the equipments I used above
- 1 x Sanyo PLC-XW60
- 1 x IR illuminator (domed shape, 180 degrees illumination, bought from Jia Ying at Sim Lim Square)
- 1 x normal mirror from IKEA (they don't sell single pieces, but set of 4s)
- 1 x PS3 Eye modified with floppy disk visible light filter
- 1 x Frosted acrylic from Art Friends
- Many pieces of laminating sheets
- 1 x cabinet
- 1 x multi plug extension
- 1 x Sony TZ notebook

* not in the list but it helps to have a wireless mouse/keyboard

More to come in part 3..

* I have managed to create the working table and a video of which is available at youtube
Video of the completed table running demo from touchlib:

On the road to my first Rear DI Multi touch table

Thanks to the help and advice from the guys over at NUI Group (www.nuigroup.com) forums especially the wonderful information supplied by PeauProductions (http://peauproductions.blogspot.com/), I have embarked on a project to build my own Rear DI Multi Touch table. I will be posting photographs and the progress of the building of the table.

This is the Playstation 3 EYE camera that will be modified to become IR capable. For people residing in Singapore, this is the packaging for the correct version of the camera to get. You can buy this at any Sony Style shop locally. Do note that some local game shops sell the European version of which I am unsure whether it is “friendly” towards modification.
PS3 Eye packaging in Singapore

The Camera removed from its shell
PS3 Eye dissection front of circuit board

The dismantled pieces:
Dissection of the PS3 Eye

The lens mount removed from the circuit board:
Lens mount front

I think I did a pretty lousy job in removing the IR blocking filter from the rear of the lens mount, look at those jaggy edges:
Lens mount

This is the IR blocking filter removed. It was damaged when it was removed.
IR Blocking filter

The visible light filter installed (cut out from floppy disk). This filter functions by blocking out visible light and letting infrared light through.
lens mount

And this is my work desk where all the mess is. The top right corner is a wide angle (180 degrees) IR illuminator that I am using for the Rear DI set up.
Messy Work desk

Next I will be making the box to sit the small piece of acrylic I got from a local art and craft shop (12″ x 18″ x 3mm(T)). It is available at Art friends for all you Singaporeans out there and costs around $8 only. Great for testing and fiddling around. I will be running tests soon using tbeta once I find time and I will post the tracking results.

On a side note: I am also intending to build a DSI table which uses a special acrylic called Endlighten. If you are living in Singapore/Malaysia and are interested in getting a piece of this very hard to get acrylic please contact me and let me know. I have managed to find a local manufacturer who has kindly indented and offered to laser cut the standard sheet (120″ x 80″ to 10 pieces of 39″ x 22″ x 10mm(T)) at $200 USD per piece. There are 4 pieces left for reserve as of this posting.