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Thermal imaging video on Blue Rov


(Oystein Skarholm) #1

Would it be possible to connect this thermal camera (or similar) to the B2 ) and feed the video up to a separate screen ? Install it in an additional enclosure and connect it to the main can. ?

http://www.unmannedsystemstechnology.com/2013/07/micro-epsilon-launches-lightweight-thermal-imaging-camera-for-uavs/


(Jacob) #2

The datasheet on this is not very clear, it says USB 2.0 or optional GigE output.

If this outputs video in a standard format over USB as a UVC device, or can output data on the network via an ethernet connection, then it should be possible to get the video through the tether. We need more information from the manufacturer.

-Jacob


(Tim Pierce) #3

Is a thermal camera going to work underwater, or would water be too dense to see very far with it?


(Oystein Skarholm) #4

Good question. The intended use was not so much to “see” better underwater as you might compare it to car mounted or boat mounted camera. My intention is to use it to locate leaks from pipelines or kinks in electrical cables that may cause resistance and thereby thermal heat. A leakage sometimes have a little higher temperature then the surroundings and could be spotted with the Thermal cam.


(Jacob) #5

This is a really good point, this might not work at all due to the absorption properties of water in the infrared region.


(Tim Pierce) #6

I have a cell phone mounted infrared camera, I’ll see if I can test that out.


(Oystein Skarholm) #7

The phone need to be submerged, I guess, to avoid surface reflection.
Filming through the glass of an aquarium should be possible if you install a small heat source in the water, a resistor or something that will send out a continuous rate of heat. (Your hand probably cool down to much as the blood pulls back due to the cold water, depending on the accuracy of the thermal unit)


(Tim Pierce) #8

I have an aquarium heater. I just need to set up a waterproof housing so I don’t melt my phone. Or my fish.


(Oystein Skarholm) #9

Looking forward to learn how the experiment goes :slight_smile:


(Oystein Skarholm) #10

@jwalser or anybody. Would this thermal camera be able to communicate through the Blue ROV?

http://www.elma-instruments.no/AkopaCMS_Elma/_res/Modules/ElmaFSSync/Mirror/brochure/4743254001725.pdf


(Jacob) #11

It looks like it because it has an ethernet/network connection and says it supports h.264 streaming.


(Tim Pierce) #12

Sorry I haven’t had time to get to this yet. All my housings are full of stuff at the moment. I may just have to improvise with a plastic bag and a scrap piece of 1/4" plexiglass. I’ll see what I can do this weekend.


(Paul) #13

Attached is a link to an example plot for the attenuation of light in seawater. From this you can see that the attenuation of red light attenuation in seawater is 100-500 times that of blue-green light.

https://www.google.com/imgres?imgurl=http%3A%2F%2Fcharkbait.evecommunity.com%2Feve%2Fforums%2Fa%2Fga%2Ful%2F2771086083%2Finlineimg%2FY%2Fwater[1].gif&imgrefurl=http%3A%2F%2Fcharkbait.evecommunity.com%2Feve%2Fforums%2Fa%2Ftpc%2Ff%2F2741078602%2Fm%2F3861032083&docid=x87TyoSv2MBJaM&tbnid=orogoDYrkd8k7M%3A&vet=10ahUKEwjWj8TPlMDVAhUE7SYKHVroBHMQMwglKAAwAA..i&w=541&h=362&bih=719&biw=1536&q=light%20attenuation%20in%20seawater&ved=0ahUKEwjWj8TPlMDVAhUE7SYKHVroBHMQMwglKAAwAA&iact=mrc&uact=8

This attenuation is why waters appears blue-green in color and underwater images amplify the blue-green colors and red/yellows appear to be washed out.

Use of artificial lighting is one way to help correct lighting (such as the LEDs used on the Blue ROV2) and there are many papers on color correction of underwater images: the following is one example - https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XL-5-W5/25/2015/isprsarchives-XL-5-W5-25-2015.pdf. It would be interesting to see if using a modified LED lights with a warm white or reddish hue rather than white light might provide a more natural tone for underwater imagery on the Bluerov2.

This alone does not necessarily mean the IR camera won’t work but it does mean that the thermal signal-to-noise ratio will quickly drop as a function of the range between the thermal target and the camera.

As mentioned above there are simple tests that one might perform to test this.

If you use an incandescent light bulb as a target you could image it directly and indirectly by placing a transparent fish tank between light bulb and camera to see how much the IR is attenuated as a function of range.

You could also test other IR targets such as a soldering iron or a tube ejecting hot water into the tank as a simulated UW pipe leak to determine useful range as a function of water temperature and leakage temp.

Sorry I’m not much help on the analytical side as I am more of an engineer than a physicist.

Sounds like an interesting.sensing idea

Best of luck.


#14

No, sorry to disillusion you all, but the optics won’t work.

A real thermal imager (like the one you pointed to) typically functions by measuring in the 7-14 micron wavelength range of IR. The imager simply measures the amount of energy collected within that band; its sensor like an array of tiny energy-collecting buckets, each “bucket” energy level coded to a pixel’s color range. The 7-14 micron band was chosen because there happens to be an “atmospheric window” (through air) in that part of the electromagnetic spectrum such that those particular wavelengths can travel without being absorbed. That way distance doesn’t affect the measured energy.

Turns out that water is almost completely opaque at those wavelengths (it might as well be milk). Even with direct submersion, at best all that you’ll measure is the water touching your (IR transparent) lens.

Parenthetically, most lenses (glass/plastic) are not transparent to those wavelengths of IR. If you’re trying to look through glass/plastic, you’ll mostly measure the glass/plastic. Since you’d of course have to house the camera behind a thick pressure window/dome, the thickness guarantees your IR camera won’t even see the wet side of the window.