The LEDs are OSRAMS FH4550 and are 850nm.  The reason why they work so well and can be used in LED-LP setups is that they have a VERY narrow half beam angle of only 3 degrees.  This allows you to place them far apart from each other, in Gabriel’s case he placed them over 3 meters apart.

I recently traveled to Los Angeles to work on a angled touch screen for a DJ who wanted to use the multitouch interaction during a show to mix beats.  We setup a screen that was spaced 42 inches on the longest side, and we decided to go with the LED-LP technique using the narrow LEDs.  We calculated the spacing minimum we’d need in order to get the beams of the LEDs to converge once the projected image started (since it was a 3 degree half angle, the distance was about 6.5 inches from edge and we spaced them about every 0.4cm with 0.6cm or so being the maximum).

Below are some pictures and a video of the LEDs all wired up and a custom camera from my store with a vari-focal lens on it:

Grade L: For application widths up to 24″

Grade XL:  For application widths up to 51″

Grade XXL: For application widths up to 78″

The Test:

• 120″ x 80″ Sheet of Endlighten (pretty sure it was XL but may have been L)
• 10 meters of 390 Ribbon (two 5 meter reels) wrapped around all the edges of the Endlighten.
• PS Eye Camera modified with 850nm band pass filter on a tripod

Below are the pictures we captured:

As you can see above we had a bit of fun standing behind it.

The crucial thing we learned was that the Ribbon didn’t travel much more than 17 inches from the edge until the light was too dim to use for DSI.  Thus the shortest distance of your screen must be less than 34 inches (or roughly 3 feet).  This translates into the largest screen able to be done for a DSI setup to be a 50 inch 16:10 setup.

Also below that is a video showcase showing the new Vari-Focal Lens and the ever popular Custom Case camera housing that we’ve created for the PS Camera.

Enjoy

New items include:

INFRARED LASERS

INFRARED LEDs

LED Ribbon from Environmentallights.com

LED Emitters/Lights

See the site for more information.  Enjoy

Over the past few months I have had some interest from customers to have a filter made for the m12 modified ps3 eye cameras that would allow it to be used not for infrared light but for the typical visible light. For those customers who purchased cameras in the past with this goal in mind to use the interchangeable m12 lens system with the camera, the only choice has been to deal with the washed out and lack of color from using the lenses without any filtering at all.

I got in contact with my filter supplier and he’s produced a low pass filter sized perfectly for the m12 mount which only allows visible light through, namely in the 400-700nm wavelengths. I have done multiple tests in varying lighting conditions and found that the filter does indeed do a very good job at keeping the colors clear and the image not washed out from the immense amount of infrared light found in sunlight and incandescent bulbs. In ambient lighting conditions that don’t have much of any infrared light, such as total darkness and fluorescent lights, the filter isn’t needed as much but is still important to have.

You can purchase all m12 mount cameras at my store now with the typical infrared band pass filters and also the new low pass filter by itself here.  See below for pictures showing the differences of having the filter on the camera versus not having one on.

(ABOVE: See how washed out the places where the light bounces off the wall are due to all the infrared light in sunlight)

(ABOVE: Colors also get very washed out)

(TWO ABOVE: Florescent light doesn’t make much of a difference)

(ABOVE: Pure infrared light is greatly reduced)

To read more about and to purchase them, see them listed on my online store here.

I decided to research the math from a bunch of different sites which calculated the answers for you, and was surprised to find that some sites differed slightly. With that in mind, I took the formulas that most of them used to work with. When someone advertises that a lens has say 160 degree field of view (FOV), what they are not telling you is that since m12 lenses can be used in 1/3 inch and 1/4 inch camera sensor bearing cameras, their advertised FOV may be different than what you get. The reason is that the PS3 Eye Camera has a 1/4 inch sensor, but calculating the FOV with a 1/3 inch sensor in mind yields a larger FOV. Also, the FOV usually listed is a diagonal FOV, not the horizontal or vertical FOV that most people care about (which reminds me of the headache back when I worked retail at Best Buy on explaining to people that a 19″ wide LCD didn’t mean that the screen was horizontally 19″). So say you see the m12 160 degree 2.1mm lens advertised. What that really means for the ps3 camera is a 116 degree horizontal FOV…confusing, arg.

The excel chart can be downloaded below:
Microsoft Excel 2007 (.xlsx)
Microsoft Excel 2003 (.xls)
If you think a correction is needed or have a suggestion on how to make it better I’d love to hear it.

I made up a first test using the below pattern:

Which I printed out and stuck to a tall candle. Then I just made some simple Papervision3D app of two planes with some bitmaps on them that rotate. The video of the test is below:

Just some fun to start with.

The perfect focus of the after-market lens is important when trying to get very accurate blobs in optical-based multitouch setups, and also when using fiducial patterns like those used by the Reactivision Team.
For finger tracking, the OEM lens can work fine, but should really only be used if on a tight budget, as the results from the more focused image will be better.
Here are some comparison shots using both lenses in a MT table:

(m12 lens)

(Comparison: OEM on left, m12 on right)
The reason why the OEM looks in focus is because the camera is only a few inches from the hand. Once you move away from it more, the image will go out of focus quickly, thus setups with the camera more than a few inches away won’t be in focus.

(OEM lens)

(3.66mm m12 lens)

(2.1mm m12 lens – Fisheye/Wide Angle)

(OEM lens)

(m12 lens)

So as you can see, the screen shots support what I said before. The OEM lens can work for either really short camera distances, or for finger tracking systems that dont need high accuracy.

My store carries both m12 and OEM moddified cameras, so be sure to check it out and let me know if you have any questions.