Johannes Luderschmidt’s Blog

Georg Kaindl the developer of the Open Source multi-touch tracking software for OS X Touché has published a blog post about how a laser light multi-touch setup can be build on your own.

He has also published a video in which he presents how the laser light multi-touch table works:

DIY laser multi-touch table – Raw camera feed from Georg Kaindl on Vimeo.

Update: Some more links:
Nuigroup LLP Wiki page
Alex P’s initial LLP setup at the nuigroup

Simon Lehmann, a fellow student of mine from the visualization classes of the Computer Sciences department at the Wiesbaden University of Applied Sciences, has created the very nice Wikipedia visualization Wivi in the work of his Diploma thesis:

Screenshot of Wivi

We are proudly announcing that the Virttable will feature at an IT exhibition called iTec ‘08 at the darmstadtium in Darmstadt, Germany on 6 and 7 November.

This is a small version of the poster with which we will present features of the Virttable at iTec ‘08:

Multi-touch table The Virttable poster

Many thanks to Melanie Seyer, who designed the poster for me!

Update: Two photographs from our booth at the iTEC:

Virttable booth at iTEC '08

Johannes Luderschmidt and the Virttable booth at iTEC '08

The second multi-touch table, that I have built is called The Virttable, which stands for Versatile Illumination Research Touch Table.

This table is the property of the department for Design, Computer Sciences and Media (DCSM) of the Wiesbaden University of Applied Sciences, which provided me with the money for the components of the Virttable. Amongst others those parts include:

• a Panasonic PT AX 200 projector
• a Unibrain Fire-i Firewire camera
• lots of Osram SFH 485P infrared LEDs
• two panes of acrylic glass
• MDF boards for the box

The computer that I have used in the Virttable is my Mac Mini.

The Virttable (Versatile Illumination Touch Table)

The main goals for the Virttable have been…

1. a cheap setup
2. It can be put into a closet when it is not needed
3. It should be easily transportable in order to be able to exhibit the Virttable and innovative multi-touch software on it on fairs
4. All parts should be easily accessable in order to test different illumination techniques and to make the Virttable maintainable.
5. It should be usable with multi-touch and object input

The first point has been acheived: The whole setup did cost around 2000 Euro.

The second point has been achieved as well:

The Virttable in the closet

The third point has been enabled by the small form factor of the Virttable: the Virttable is 70 cm high, 74 cm wide and 54 cm deep. The wheels underneath the Virttable’s body make it rollable. The handles to the sides make it easy to carry and to attach tension belts in the trunk of a car.

The fourth point is provided by the lid and the hatch: The LEDs and the acrylic glass can be accessed via the lid and the projector, the computer and the camera can be accessed via the hatch.

The fifth point has been more complicated: A DI setup would have been easiest to support as well multi-touch as object interaction. However, DI is not as efficient as FTIR and thus we decided to make a hybrid approach by applying a mixture of DI and FTIR:

On the left there is no illumination. On the second photo the Virttable is FTIR illuminated. The third photo shows only DI illumination. The right photo shows the hybrid mixture of FTIR and DI: Touches are bright and precise and the fiducials of the objects are evenly lit.

We have also tried the DSI technology like it has been described by Tim Roth by using a Plexiglas EndLighten acrylic glass pane but the results have not been satisfying for us.

In the Virttable DI is provided by a few aluminum bars equipped with Osram SFH 485P LEDs underneath the tabletop. The bars are diagonally emitting their light onto the underside of the acrylic glass. Each LED is covered with a piece of masking tape to disperse its light evenly and to prevent hotspots. With this DI technique fiducials like those from the reactable can be used in this setup.

FTIR is provided by Osram SFH 485P LEDs in aluminum bars, which emit their light into the polished edges of the acrylic glass.

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I’ve found many instructions in the nuigroup forum on how to configure the Pointgrey Firefly MV Firewire camera in a multi-touch setup and especially with the Touchlib.

As information about this topic is widely scattered, I want to write down some helpful steps on how to configure the Firefly in this post.

Pointgrey Firefly MV with Tamron zoom lens mounted with tripod bracket

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