[SS2S-Main] Re: Infrared webcam

  • From: waaslandwolf <waaslandwolf@xxxxxxxxx>
  • To: sugarshot@xxxxxxxxxxxxx
  • Date: Sat, 17 May 2014 10:51:17 +0200

Mattias,

Great work! I am curious how you did the gradient mapping post-processing,
care to elaborate?

Cheers,
David.


On Fri, May 16, 2014 at 9:22 AM, Lampe, Mattias SLC CT PEK <
mattias.lampe@xxxxxxxxxxx> wrote:

>  Hi all,
>
>
>
> after some experimenting I have to correct my previous statement that a
> modified webcam (after removal/exchange of the IR filter) is unsuitable for
> thermal imaging.
>
>
>
> Here are my learnings:
>
> -          Objects hotter than approx. 260 degrees centigrade (about 500
> degrees Fahrenheit) seem to “light up” in the near infrared image. The
> hotter the brighter, so at least a relative temperature comparison is
> possible, to some extent. The tip of a hot soldering iron, for example,
> appears to shine quite brightly when looking at it through a modified
> webcam.
>
> -          Hot combustion gases show up brightly in the IR image, even if
> they are invisible to the naked eye. (Not sure if it’s the CO2 or some
> other gas that causes the effect.
>
>
>
> As a proof, here are some videos taken simultaneously with three cheap
> webcams of the same brad and model. One had the IR blocking filter removed,
> anouther one had the blocking filter replaced by a filter blocking visible
> light (i.e. only letting IR pass to the sensor), and the third camera was
> not modified at all.
>
>
>
> The so-so quality of the videos is not due to the camera but due to the
> slow computer used for recording and encoding. If the videos don’t play in
> your browser, downloading them may help.
>
>
>
>  This is me frying an egg as seen by a normal webcam (visible light only):
>
>
> https://onedrive.live.com/redir?resid=6838BE39B86A56AC!178&authkey=!AKrXza_7QKYre8s&ithint=video%2c.mp4
>
> Please note the familiar short, blue gas flame.
>
>
>
>
>
> Looking only at the IR componente with a modified webcam, the flame looks
> totally different:
>
>
> https://onedrive.live.com/redir?resid=6838BE39B86A56AC!176&authkey=!AOAS5uk5p0QffiA&ithint=video%2c.mp4
>
>
>
> The hot gas moving upward is visible, and after shutting down the flame
> you can see the metal frame “glowing” for quite a while. The frying pan
> itself does not light up because it never really exceeds 200 degrees C.
>
>
>
> Here is a post-processed version of the video with a so-called
> gradient-mapping applied to the IR video:
>
>
> https://onedrive.live.com/redir?resid=6838BE39B86A56AC!177&authkey=!AKwVxXkHqhw0Z_k&ithint=video%2c.mp4
>
>
>
> The camera that only had the IR blocking filter removed but no blocking
> filter for visible light installed took the following video:
>
>
> https://onedrive.live.com/redir?resid=6838BE39B86A56AC!179&authkey=!AOZAg8XGkhGL0aQ&ithint=video%2c.mp4
>
>
>
> (The videos were recorded simultaneously, and the lights in my kitchen are
> fluorescent ones, containg very little IR. Things look quite a bit
> different under incandescent lights.)
>
>
>
>
>
> So after initial doubts I do see some value in using modified webcams for
> IR imaging of rocket motor tests. Compared to low-end FLIR cameras the
> resolution is higher and the cost is nearly negligible (less than 15$ for
> the cameras I used). You can observe the flow of exhaust gases and see
> where things get really hot (>260 degrees), and I could imagine that IR
> penetrates the smoke a little bit better than visible light.
>
> Absolute temperature measurements, however, would probably be impossible
> or at least require quite a bit of calibration work.
>
>
>
>
>
> Only a single egg was hurt in the process of recording the four videos ;-)
>  (The other 11 eggs from the same box will be hurt later.)
>
>  Hope it’s interesting. I’ll send the cameras to Vicente, who started
> this thread.
>
>
>
> Have a good day!
>
>
>
> Mattias
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
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>
>
> *From:* sugarshot-bounce@xxxxxxxxxxxxx [mailto:
> sugarshot-bounce@xxxxxxxxxxxxx] *On Behalf Of *Lampe, Mattias SLC CT PEK
> *Sent:* Sunday, May 04, 2014 10:12 AM
> *To:* sugarshot@xxxxxxxxxxxxx
>
> *Subject:* [SS2S-Main] Re: Infrared webcam
>
>
>
> Hi,
>
>
>
> I think removing the internal IR filter works with most webcams, and if
> you want to make sure you ONLY see the infrared but not the visible part of
> the spectrum, you can add a filter that only lets infrared light pass. A
> piece of overexposed and developed color negative film (like from the
> beginning of a film roll) works quite well for that purpose. It blocks
> nearly all visible light and is quite transparent for IR. If you know
> someone who still shoots pictures on film or someone who did so in the past
> and kept the negatives, they should be able to find a suitable piece of
> material.
>
>
>
> Not sure how you want to use the IR camera, but you should be aware that
> it will not be a thermal imaging device. It will be sensitive only to near
> infrared, and in order to emit those wavelengths a body must be quite hot
> already, i.e. close to glowing.
>
>
>
> I have a few unused webcams at home and will check if they can be
> converted.
>
>
>
> Have a great day!
>
>
>
> Mattias
>
>
>
> *From:* sugarshot-bounce@xxxxxxxxxxxxx [
> mailto:sugarshot-bounce@xxxxxxxxxxxxx <sugarshot-bounce@xxxxxxxxxxxxx>] *On
> Behalf Of *James Fackert
> *Sent:* Saturday, May 03, 2014 1:18 AM
> *To:* sUGAR sHOT TO SPACE LIST
> *Subject:* [SS2S-Main] Re: Infrared webcam
>
>
>
> here is one, $30.
> http://www.adafruit.com/products/1567
>
>
>
> On Fri, May 2, 2014 at 9:53 AM, Lyn Berry <lyn_berry@xxxxxxxxxxx> wrote:
>
> Hi
> I am no expert but if memory serves webcams contain an IR filter. If the
> filter is simply removed the webcam becomes much more sensative to the IR
> part of the spectrum.
> QED
> Regards,
> Lyn Berry
>
>
>
> On Friday, 2 May 2014, 12:52, Vicente Alvero Zambrano <
> vicente_alvero_14@xxxxxxxxxxx> wrote:
>
> Hi,
>
>
>
> Does anyone know and is willing to turn a webcam into a webcam with
> infrared vision for the series of motors VIC and to study the ablative
> materials?
>
>
>
> Cheers
>
> Vicente Alvero
>
>
>
>
>

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