the singapore river as a psychogeographical faultline

today me and dominic succeeded in approximately aligning the camera/projection/fiducial setup with the visual response in my flex swf. i've switched to using CS5 Flash Builder because I eventually want to publish it as an Air app. so far its been sweet using reactivision with TUIO AS3 library.

we are using a 3.6mm lens for the PS3 Eye and the projector is at a resolution of 1024 x 768 x 96hertz. apparently hertz refers to the refresh rate and when i set it higher than 120 hertz it says out of range. this is all gobbledygook to me too but what i know is that when i stare at the back of the projector and shake my head (oh the migraine!), for a split second i see the light dividing itself into bright bands of red, green, and blue...

Dominic and Edward have been helping me with the projector mounts and testing the setup for the table. while studying mechanical engineering, Edward previously built other things with aluminum profiles, so he recommended using these aluminum bits to build the mount instead of wood (as it would help conduct the heat away from the projector better!)

despite its complex appearance, (well, to construction noobs like me) it's actually a rather simple and modular system to build with, along with other parts (gussets, glass/mirror mounts, hinges, etc). plus it has the benefit of being lightweight and easily adjustable for height/length...



one thing is that you MUST remember to do in advance is to: TAPPING THE SCREWS. and what is this mystical tapping business? this refers to the process of creating a thread for the screw to go into. according to Edward you can do it by hand, but of course it is always ideal if you can just get the supplier to thread it on the spot. saves you from the heart attack of suddenly having to google for hardware stores in the city area...

25 JULY: me and dominic conducted the first preliminary hardware tests within the actual physical box which will be used in the exhibition. the following discoveries were made:

• IR light reflects somewhat differently from visible light. rather than defusing in the same way that visible light usually defuses on normal surface, it bounces straight off some surfaces which might be expected to absorb visible light, like cardboard
  
• even though you cannot see IR light, IR LEDs still get very hot if left on for long. also, projectors get very very hot as well, so computer fans and good ventilation/air conditioning will be ESSENTIAL in a DIY tangible table setup
  
• infrared light hotspots (insufficient diffusion and spotlights instead) adversely affect the detection of fidicuals
  
• accidentally sticking your finger inside a computer fan does not actually result in injury or death
  
• tracing paper will warp with moisture over time. an additional acrylic sheet is essential for holding down tracing paper and for improving sensation of touch on the touch surface.
  
• using developed film as a "poor man's IR filter" is not effective enough for the use of a tangible touch table which wants to detect fidicual symbols. purchasing specialised IR filters and additional focal lenses will be crucial to the success of the project.

29 JULY: After significant wrangling and wrestling with Singpost's Speedpost service, I received the 2nd PS3 eye camera with m12 mount with 850nm IR filter and set of lenses ranging from 2.8mm to 16mm. (these were purchased online from peauproductions, which stocks a lot of essential equipment for DIY touch surfaces)

With the 16mm lens, reactivision can now detect 3cm fiducials at a range of 1 metre!

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footnote: i assumed i needed the BIGGEST lens initially, but later dominic showed me that the smaller lenses could SEE MORE, and the final lens we went with for our table was 3.6mm