Hi Everyone,

I’m at my wit’s end with regards to getting blobs...or anything to work for that matter.

My set up is as follows.

- 1/2” 4’x3’ acrylic, frosted on projection side (rear)
- 164 IR LED’s around the perimeter (1 led per inch)
- Windows XP SP3 running on a Macbook Pro in bootcamp
- Dell DLP Projector running at 800x600/1024x768
- Sony HC-52 MiniDV camera in nightshot mode (N.S. light turned off) with visible light filter (strip of film leader)
- MTMini Package and/or Touchlib Rev 359 (the 393 just crashes every time I try to run it!)

While based on some of the windows, I should get a half-way decent reading, the rectify window inevitably displays a useless image that is either b&w snow (grain) or flickering chunks of gray pixels.  Either way it is unusable.  Not that it helps at all, but I’ve posted a pic below.  Don’t worry about the sliders, I’ve tried adjusting them six ways to Sunday and still can’t get blobs! :-(

Any and all help is greatly appreciated!  I have to have this finished by July 13th!  Thanks!

Boz

After looking at your pic i can say that you arent getting an FTIR effect, in your dvslcapture0 window should when you touch the screen it should you should get a bright inputs which you are not getting such as in the attached picture. This could be occurring for a number of reasons you may not have leds or you may not be getting an FTIR effect because you have one side that is frosted. Or it may be the fact that your screen is pretty big 4’x3’.

Try angling your leds a little to get a better result.

Taha

Also why are you using the invert filter for FTIR? Your using the DI configuration for FTIR , change your config file to the apropriate one.

Also angle your leds a bit more until you get better blobs , and add another strip of exposed film negative or floopy disk internals over your camera.

Thanks guys,

I think that my problem might also be stemming from not clear enough acryilc edges.  I’m going to try torching them tomorrow.  In addition, I ditched my Sony DV camcorder for a M$ VX-6000 which seemed to get infinitely better results.  Odd perhaps?  I’m not sure.  I’m so new to this.  Once using the M$ webcam, I was able to see blobs at the edges of my acrylic, but they faded away as I got to the center, which says to me it’s an edge thing.

As far as tilting the LED’s, this is problematic as they are pressure fitted extremely tightly in their channels, making it pretty much impossible to extract and re-seat them without pliers of some sort (which would risk ruining the epoxy) :-( So hopefully polishing up the edges will do it!

Will let you know how it goes!

Thanks again,

Boz

If you get blobs near the edges and not the center you have a serious problem , it could be that either the acrylic edges are not well enough polished (if you look on one side of the acrylic , can you see the other?) but I think that’s not the problem.

I think you are getting TIR and not FTIR , the light inside the acrylic is not refracting enough , you need to angle the leds a little down or up , we have a FTIR angle calculator somewhere on this forums.

Can’t you put something at the end of the bottom part of the channel at it’s end only , to angle the part facing the acrylic a bit down?

If that dosn’t work your acrylic is probably to big , 4 x 3 is really big for FTIR , your best bet would have been a DI based setup , you could probably retrofit your leds to convert it into DI.

If you can’t get it working with FTIR , go and buy a few IR Iluminators and try a DI based setup , it would acomodate your needs better.

Well that’s kind of a bummer.  I really hope that’s not the case as I’d have to start over from square one.

I’ll do my best to polish the edges and try to angle the LEDs somewhat.  Hopefully that will fix it!

If it doesnt work i suggest adding more leds and leds with a narrower beam angle… around +-15 deg.... that will help with the problem.

Taha

Well, let’s see…

flame polished the edges
re-angled the IR LEDs

No luck.  IR light still doesn’t reach the center of the acrylic and only barely makes it past the edge (maybe 2 inches).  And yes, there’s enough electricity powering them. :-(

Tried taking a rail of LEDs from the frame to attempt a quick DI set-up....and it almost worked, but I had a severe hot spot in the center of the acrylic!  :-(

Oh well, back to the drawing board.

Well for the size of your acrylic sheet i dont think you have enough leds… but i think the main culprit is your screen, cause its frosted i think its not creating total internal reflection....

Taha