Infrared Webcam HOWTO

Geoff Johnson writes "Some of the Slashdot readers may be interested in this page I put together. It describes how to make an ordinary webcam see in the near infrared waveband."

Comments

duh

[oliverthered]

Let me guess, remove the IR filter from in-front of the lens.

Re:duh

[m50d]

Well, and replace it with one to block visible light. But yes, that's about it.

Re:duh

[oliverthered]

You don't need to for 'night vision', which is what I expect most people will be interested in.
Full colour (maybe a tiny bit washed out because of the extra IR) during daylight, and at night switch on the IR light and you've got an IR camera.

Near IR isn't that interesting, except humans cant see it, what would be cool is if the chips could pickup far IR so you could see heat.

Re:duh

[budgenator]

Cadillac has an interesting thermal system, I haven't really dug into it in depth, but basicaly the sensor is a bunch of capacitors similar to a ccd sensor. When the IR image is focased on the sensor, the heat causes the diaelectric between the capacitor plates to warm up and expand changing the charge on the capacitor and make it readable.

Sooner or later someone is going to hack the system for some serious geek factor. I could see someone hackering several of these different systems together for some cool false-color IR video. I used to do quite a bit of IR photography used Kodak's IR false-color slide film, green showed up as blue, red was green and IR was red if memory serves me correctly. The biggest problem was the film used the old-fassioned E4 process, so you either had to send it to Kodak or do it your self

Re:duh

[huge colin]

Cadillac's system was actually a Barium Strontium Titanate (BST) module, developed by Raytheon. It required a thermal differential in the scene from frame-to-frame to be able to see anything, and thus a "chopper" wheel (a rotating slotted disc) had to run in front of the detector. The picture would smear and was generally low-quality. The module used by Cadillac was also rather low resolution (160x120, I believe).

The alternative to BST is microbolometer technology, developed by Lockheed Martin / BAE Systems and others. A microbolometer array consists of vanadium-oxide bridges that vary their resistance when exposed to thermal radiation. The scene will occasionally need to be "shuttered" (i.e., zero all the pixels against the back of a shutter mechanism to cancel the thermal drift that creeps in over time.)

Unlike light-amp, true thermal imaging allows you to see in complete darkness. And unlike projected-IR, it isn't limited in range by any kind of IR-transmitter. And unlike either of those technologies, it allows you to very quickly find humans (or other mammals) in a scene, and it allows you to see where things used to be by the heat-shadow that they've left.

Can it see through clothing?

[Anonymous Coward]

Cause I'd really like to take my PC to the beach and get webcam shots of da honey's.

Re:Can it see through clothing?

[Anonymous Coward]

Im sure they wouldn't find anything suspisous about a guy with a laptop with webcam attatched.

Re:Can it see through clothing?

[anagama]

This was covered on slashdot a long time agao.

But yes, it can see through clothing to some extent.

infrared wecam!

[Anonymous Coward]

that's just fantatic!

cached link of video if it dies.

[Organized Konfusion]

http://homepage.ntlworld.com.nyud.net:8090/geoff.j ohnson2/2004-08-08.avi

Burgler Cam??

[GreyPoopon]

Does anybody think that coupled with a pure IR source of light this item would be useful in catching would-be prowlers without alerting them? OK, probably a stupid idea...

Not all cheap webcams have filters.

[OneDeeTenTee]

If you're lucky the webcam won't have an IR blocking filter.

You may want to check it with a remote (or just put your IR passing filter in front of it) before you take it apart.

Re:WEcam HOWTO?

[InfiniteWisdom]

I've heard of a webcam, but never a wecam.
Hence the HOWTO, duh!

OK.....

[mr_z_beeblebrox]

So the article details a cool hack, props. What I want to know is.....why was I able to download the 6.9 MB AVI file at the end. Isn't his server supposed to die or something? I can never download the files referenced by a /. link. Is something wrong?

this is true of almost all modern cameras..

[Mark19960]

altho, most that ive seen ahve the IR filter directly attached to the CCD.
you would remove the CCD, then remove the 'piece of glass' from it.

some cameras achieve this effect differently, I have not quite worked out how they work.
For example, Sony camcorders that have 'nightshot'
also have an IR filter, but I suspect its something different. the switch not only engages some IR illuminators, but does something in the lens block itself. (switches something in/out mechanically)
I know that the IR filter at the CCD remains there, its in a fixed position.

I am now curious and have to dissasemble a sony lens block to see :)

I used to work on cameras, and I have removed the IR filters on cameras before for a bit of fun.

if you can get enough IR leds going you can get it pretty well lit.
Altho, the resolution is probably not going to be that great at a distance.

Re:Infrared Technology and the Chinese Threat

[budgenator]

Actualy this is pretty much WW-II style technology, the old Sniper-Scopes used active IR like this web-cam mod. Now the problem is passive IR is so common firing up an IR illuminator is like painting a bull's-eye on your forehead. It's so common, we put blue filter on our flashlights to block the near-IR and IR output; visible light is less damgerous the IR at night!

The day is still young...

[Shazow]

Everyone is still asleep from their late-saturday-night D&D sessions.

Give it time... :-)

Look for heat loss?

[crow]

Will this capture the right range of infra red to detect heat? If so, then I could see using it with a laptop on a cold day to see where I need to improve the insulation on my house.

If you want a time-lapse capture app for free...

[maird]

...Get one here: http://www.mair-family.org/Downloads/ Geoff says the software he had isn't very good. I couldn't find anything I was prepared to pay for so I wrote my own and publish it at that link. Sorry Windows only and WMV output. You can read the feature list for yourself but, in terms of Geoff's difficulty, it will capture frames at between 4s and one hour per-frame (configurable) and create a 15fps WMV.

Go ahead, /. my web server...Hopefully my ISP is tolerant.

alternative approach

[tverbeek]

Or just accelerate your webcam enough (toward the object you wish to photograph) to blue-shift the infra-red into the visible frequencies. Put it on a really-high-speed ferris wheel or merry-go-round and synchronise the snapshots to its rotation if you want to keep it "stationary". Compensating for the doppler shift in the signal from the camera is left as an exercise for the reader. But no disassembly or modification of the camera needed!