Comments on: The Multi-Touch Table Virttable [Update]

By: virttable « belshi.com

virttable « belshi.com — Wed, 31 Mar 2010 11:08:36 +0000

[...] http://johannesluderschmidt.de/lang/en-us/the-multi-touch-table-virttable/153/ [...]

By: LED Tables | Robot Monkeys

LED Tables | Robot Monkeys — Fri, 26 Mar 2010 01:22:12 +0000

[...] cables to pass through. What I really want is a multitouch display like either of these two guys are building. However, a multitouch is still pretty hacky and more DIY than I want right now. I [...]

By: johannes

johannes — Sun, 21 Mar 2010 16:27:12 +0000

hi hugo as you said: optimization. i frequently experienced disturbances of the blob tracking by ambient light i.e. by daylight or by light sources that contain high amounts of infrared light like halogen spotlights. the stronger and the more LEDs you use for the illumination the higher will be the contrast of the blobs in comparison to the ambient light and the easier blobs will be to track by the tracking software causing a higher sensitivity of your table for touches resulting in a light-pressure surface even in problematic surroundings. however, even with a strong FTIR light source there are some things to keep in mind:

in problematic surroundings sensitivity can be enhanced by amplifying the hardware contrast of the camera.
in the Virttable blobs show a nice contrast even with four halogen spotlights directly above the table. however, if someone interacts with the Virttable in such surroundings, they will throw a shadow on the table's surface, which interferes heavily with the background removal filter of standard tracking applications like tBeta/CCV or the Touchlib. Thus, ambient light must still only be indirect.
As I need quite a bit of power for so much LEDs, I use a standard ATX PC power supply. The poor quality of that kind of power causes the LEDs to flicker a bit, which impairs the tracking. It is better to use another power supply (e.g. there are dedicated LED power supplies). Oddly enough, lots of DIY multi-touch tables rely on ATX power supplies.

By: HSobralP

HSobralP — Sun, 21 Mar 2010 05:22:09 +0000

Hi, very nice work. Why do you changed FTIR aluminum setup to this new one, some problem with the LEDs ilumination? optimization ?

By: // Commented Out » Blog Archive » Preparing for Multi-touch in Flash – A Link Dump

Tue, 06 Oct 2009 14:14:02 +0000

[...] http://www.tactineo.com/ http://www.ideum.com/products/multitouch.html http://johannesluderschmidt.de/lang/en-us/the-multi-touch-table-virttable/153/ http://www.hp.com/united-states/campaigns/touchsmart/#/usnews/ [...]

By: Digital Art & Technology » Blog Archive » Multitouch Table

Digital Art & Technology » Blog Archive » Multitouch Table — Thu, 02 Jul 2009 10:23:26 +0000

[...] Reference: http://johannesluderschmidt.de/lang/en-us/the-multi-touch-table-virttable/153/ [...]