4 Dollar way to get rid of Projection Blobs…maybe
Posted: 16 February 2009 03:11 PM   [ Ignore ]
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http://www.surplusshed.com/pages/item/m3002.html

Okay, besides American Science and Surplus, this is my new favorite site

From reading the website, i found out i’m throwing IR blobs on my screen from my projector..  I know I need to get a hot mirror, but I found these....

3” DIAMETER INFRARED HEAT ABSORBING GLASS

Made by Corning Glass Works this is 3” diameter by 3/16” thick infrared heat absorbing glass. Heat absorbing glass is used to reduce the amount of heat transmitted through an optical system. Heat absorbing glass effectively absorbs wavelengths beyond the visible spectrum. Unlike a hot mirror, which reflects the infrared wavelengths, the heat absorbing glass absorbs the infrared radiation and then dissipates the heat into the air around the glass. Heat absorbing glass can also be utilized as a shortpass filter, in order to pass the visible and block the IR. It has a ruby red coating.

$4 USD

I also found throwing mirrors on there too.. from someone elses post on the site.  Very kewl stuff :D

for 2 lens, and 2 mirrors, my shipping was 5 bucks.
~Doc

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Posted: 16 February 2009 04:21 PM   [ Ignore ]   [ # 1 ]
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Looks great. I love surplusshed.com. I got my mirrors there too.

Please let us know how this works at cutting out the light from the projector.

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Posted: 20 March 2009 06:06 AM   [ Ignore ]   [ # 2 ]
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I ordered two of those IR heat absorbing glasses. I received them today, but was greatly dissapointed to discover that they do absolutely NOTHING. No change in the projector false blob, not even a slight change in its intensity. I even placed both of them one in front of the other to see if that makes a difference, but still nothing :-( :-( This thing just seems like a round useless piece of glass. I really need a reliable affordable IR hot mirror. I found a company in Germany but they wanted 600 euros!!!! Anyone knows of any good company? I’m desperate here :-(

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Posted: 20 March 2009 07:05 AM   [ Ignore ]   [ # 3 ]
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I ordered two as well.  I am using one and I think it does help with the blob in the “rectify” windows.  In the camera window I get a bright light/blob.
But in the other windows and tbeta calibration windows after I remove background the bright light/blob is gone with the mirror.
I have no problem running my applications, without the mirror, the blobs always shows up.  This mirror filter out infrared light from
your projector, but your camera might pick it up somehow, perhaps the Infrared light from the projector is has different wavelength
than your IR filter from the web-cam.  However, with 7 layers of over-exposed film.  My set up work like a champ.  I need to get a band pass filter though.
For now I can try most of the software even when my halogen lights are on.  I am not saying the “heat absorbing glass” does everything, but it does help
out with the IR light from the projector.

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Posted: 25 March 2009 07:09 PM   [ Ignore ]   [ # 4 ]
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I am using one and I think it does help with the blob in the “rectify” windows.  In the camera window I get a bright light/blob.
But in the other windows and tbeta calibration windows after I remove background the bright light/blob is gone with the mirror.

The projector blob always goes away when you remove the background. The thing is, any slight motion of the camera, the projector, or even the whole table will probably cause it to show up again. At least that’s my problem here. In my case, even a change in the colour of the image projected by the projector will cause the false blob to appear out of nowhere, because the lamp’s light intensity changes when it projects white bright images for example.
But I would love to see some screenshots of your tBeta application, to illustrate your configuration, if that is possible.

I have no problem running my applications, without the mirror, the blobs always shows up.

Here you mean that without the heat absorbing glass the false blob always shows up? So when you use it, the false blob never shows up?
I have tried it with my setup and it doesn’t seem to make a difference.

And one last thing, how did you manage to mount the glass in front of the projector lamp? I’m trying to find a way to mount mine, and I have already seen you have finished yours, so any help is appreciated.

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