[SS2S-Main] Re: Infrared webcam

  • From: John Doe <waaslandwolf@xxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Sun, 18 May 2014 19:45:53 +0200

Mattias,

Thanks for the detailed explanation. Looks like the "Mattias IR webcam gradient 
map" will be another good tool on my rocketry belt in the future!

David

> Op 18-mei-2014 om 08:52 heeft "Lampe, Mattias SLC CT PEK" 
> <mattias.lampe@xxxxxxxxxxx> het volgende geschreven:
> 
> Hi David,
>  
> I suppose there are probably many ways of doing it. I used GIMP (a free image 
> processing tool, maybe comparable to Photoshop) and a plugin named GAP that 
> allows importing videos. The frames of the video will be represented as 
> layers of a single image, and it is possible to apply filters or other 
> transformations to all layers (i.e. all video frames) at once.
>  
> The filter I used is called “gradient map”. There are a number of predefined 
> color gradients, but it’s also possible to define one’s own. I modified an 
> existing one to create a gradient from dark blue over cyan, green, yellow, 
> orange to red. After applying the “gradient map” operation to the image, the 
> dark parts of the image will be mapped to the “cold” colors and the bright 
> parts to the “warm” colors.
>  
> I takes a bit of processing time (depending on the resolution and number of 
> frames in the video), but only a few mouse clicks.
>  
> “Gradient map” seems to be the “official” term for it, so I think the 
> function will have the same name in Photoshop or other programs.
>  
> It shouldn’t be too hard to even apply this kind of operation “on the fly”, 
> in real-time when recording the video, but that probably requires a bit of 
> programming.
>  
> Have a good day!
>  
> Mattias
>  
> From: sugarshot-bounce@xxxxxxxxxxxxx [mailto:sugarshot-bounce@xxxxxxxxxxxxx] 
> On Behalf Of waaslandwolf
> Sent: Saturday, May 17, 2014 4:51 PM
> To: sugarshot@xxxxxxxxxxxxx
> Subject: [SS2S-Main] Re: Infrared webcam
>  
> 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
>  
>  
>  
>  
>  
>  
>  
>  
>  
>  
> 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] 
> 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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