after being part of the nuigroup for roughly one year i wanted to show off some pics and some information about the second table that i have built.
the nice part about the Virttable is that i have got the money to build it from the Computer Sciences department of my university, which is the Wiesbaden University of Applied Sciences. By the way, our Computer Sciences department has very nice information visualization research possibilities under the lead of my professor Dr. Doerner. so anyone, who is interested in studying Compuer Sciences in Germany and likes multi-touch and visualization: Wiesbaden would be a good choice for you for sure
to get back to the table: versatile illumination regards the different illumination techniques that you can use with the Virttable, which include FTIR, DI and DSI. FTIR and DSI are supported by 48 Osram SFH 485P LEDs that sit in aluminum bars to the sides of the acrylic glass. we have got both a pane of regular 8mm acrylic glass with polished borders and a pane of Plexiglas Endlighten XL glass with polished borders that we can switch by removing the lid and changing the glass pane. anyway, our DSI results were not good. thus, we are now using only the regular acrylic glass pane (or to be more precise: we have tried out toluene on the Endlighten glass, which attacked the pane’s surface and ruined it).
DI is supported by 3 aluminum bars with SFH 485P LEDs underneath the surface of the table that emit their light diagonally on the table’s surface. these are only a few but they are enough to illuminate the surface in a way to allow the use of fiducials on the table. check out this image to understand what i’m talking about (high resolution after a click):
on the left there is no illumination. the second picture shows only FTIR, 3rd only DI and finally on the right picture there is the hybrid solution with FTIR and DI. this works nicely.
we’ve built the Virttable’s setup in a way that everything is accessibe and can be exchanged easily. something that is not shown in the CAD drawing are two fans that we use to guide the hot air inside of the casing out through the ventilation openings.
some ingredients that we used for the Virttable:
- Panasonic PT AX 200
- Pointgrey Firefly MV and Unibrain Fire-i
- optical highpass filter B+W IR filter 52 093 (i tried 2 thorlabs bandpass filters but they did not work AT ALL for me. the b+w filter, which is made for photography, costs the half and yields better results than the negatives and lots better results than the thorlabs filters.)
- A Mac Mini
- for multi-touch tracking: fast touchlib version from AlexP
- for fiducial tracking: reacTIVision
- Gerrites OptiTrans
- lots of Osram SFH 485P
here is an ‘x-ray’ image of the Virttable:
and a view from all sides:
and a front/top view:
and finally you can see that i measured the dimensions in a way that the Virttable fits in a locker: