Thursday, August 24, 2006

Laser Show - I wanna be ILDA

This is a club I would join. How cool would this look on a resume? "Member International Laser Show Designer Association".
There are actually standards for laser shows which is interesting. I suppose the most significant is "do not look into laser show". Or possibly "do not use laser show to dissect spies".

I needed to do a little research on the ILDA mainly for the file format. Laser shows are basically vector art. Think "Asteroids" or "Tempest" if you recall your 80's video games. Or think Corel Draw or Adobe Illustrator or AutoCad if you know your computer graphics. The rest of you remember high school geometry - two points can be joined by a line. OK... think "connect the dots"...

A laser show is a picture created by defining a set of points (vertices) and drawing lines between them. The data for the show I've built is created in Pangolin Laser Show Designer. It's pretty basic, and hard to use on the Amiga (I need a new mouse, or a digitizer). It also stores the points data in a binary file using the .LSD format.
Most laser shows now use the .ILD format, which is slightly different and allows the more sophisticated gear laser shows are packing these days.

I wanted to create shows using software I knew how to use, or software that I could get for cheap-as-free ( as opposed to buying a copy of Mamba Black which would set me back E299 -what's a Euro going for these days?).

Fortunately I stumbled across someone's attempt at building a laser show controller in Visual Basic, which gave me some of the file formats. I've been monkeying with the program for some time now, but I can now say I've kludged a very nice system:

  • design a show using Rhinoceros
  • animate the show with Rhino plugin Bongo
  • export the show as a series of .DXF files with a custom script
  • import the files into the VB laser show
  • export the files as an animated .LSD file from VB laser show
  • port the files from the PC to the Amiga using a serial interface.

    "If you've done six impossible things before breakfast, why not round it off at Milliways, the Restaurant at the End of the Universe"

    I think this qualifies....

  • Monday, August 14, 2006


    The 5 year old has discovered the second law of thermodynamics - "When you put more cold water with hot water the cold water surrounds the hot and makes it cold BUT when you put more hot water than cold the hot water surrounds the cold and makes it hot! the hot water is the good guys and the cold water is the bad guys"

    I'm so proud...

    Saturday, August 12, 2006

    That Darned Trogdor

    Cleaning out the filing cabinet today in a futile organization exercise (entropy strikes quickly here) and came across my brother's cartoon work. Me and the family (pre sub-urchin) and our pesky dragon. Brian keeps a very meticulous blog of his life at Liverspot, but he's never published a cartoon as far as I know. Check 'em out here:

    Trogdor Title Page

    Trogdor in Train Wreck

    Trogdor in Ice Follies

    I said consummate "v"'s !

    Tuesday, August 08, 2006

    Laser Show - Irony

    A short in the system causes a blown fuse. Where's the short? In the fuse. One of the tabs was brushing up against the case. Can I still say D'OH!?

    Sunday, August 06, 2006

    Laser Show - Hardware

    This was the fun part. Fun as in "not particularily, but challenging, frustrating and it gave me something to think about while I was up at 2 AM soothing a screaming child".
    That kind of fun

    1. DC coupling: This thing is analog! How retro can you get? DC coupling does something to the analog input siganl so it can drive the scanners. I did a lot of work at UBC on signal theory and electronic measurement, but I still don't get what this actually does. Had to build it myself though - from designing the circuit to etching the board to soldering the parts. Worked first time too.

    2. Scanner Amplifier: Takes the input from the signal and amplifies it to drive the scanners. I shorted this out when I thought the heat sink was grounded. It still sort of works, but I may have to send it in to get it checked. My bad.

    3. Scanners: Your Head Asplode (Joke). These are basically small mirrors mounted on electric motors that oscillate in sync with the signal. One for the X axis and on for the Y axis. Think of it as an etch-a-sketch with light and that's about it.

    4. Laser Power Circuit: power to the laser. Nuff Said.

    5. Laser: 532nm 30mW DPSS TTL laser to be specific. Hella bright. And green. And dangerous. Still won't cut a spy in half, or even burn a hole in a paper cup, but it's still cool.

    6. Case: This was really the hardest part. Where to put it all. I've got a lot of junque electronics around so finding a case was not a problem. Finding a case with 120V power socket, plenty of space, fans and heavy enough not to vibrate too much was the problem. I thought it would be cool to put in all in a translucent green AGFA scanner case, but it wouldn't fit. I finally settled on this 7 bay SCSI CDROM tower from our old library. I don't think anyone would really miss it. I gutted the CD drives (quad speed - how quaint) and power supplies and with a little bit of fudging all fit in. I also mounted the laser and scanners on a 1 kg metal plate with some rubber grommets for vibration control. I'd love to be able to stuff the Amiga board in and run an LCD panel on the outside.
    Next version.

    7. Power connector: lots of switches - one for the laser (key lock controlled), one for the mains, fuse and breakers. And of course, I can't find the key.