Thank Tim Jones for this.

[Outta Control]

So Tim Jones asked an excellent question,

"Does thermal work in shallow water?

For example, if you survey a coastal are where the water is shallow. Would you detect large animals like sharks or would the water temperature render the thermal sensor ineffective?"

To answer this question we need to understand liquid density, how close the target is to the surface, and temperature differences. So here is non-scientific example of the complexity to understand infrared.

So the answer to Tim's question is YES, BUT we all need to understand and apply the variables when we do thermal testing.

Note: Temperature is not exact but gives you a general idea.

Experiment #1
A. Two Skittle candy are submerged in a small bowl

Observations:
The water temperature is at 68F. While the Skittles' temperature is at the same temperature.

B. Thermal with FLIR's MSX turned on.

NOTE: You can see the candy's outline.

MSX Turned off

Experiment #2
A. A heated coin is submerged in chocolate milk in a small bowl

Observations:
Chocolate milk has a higher density than water, while the coin has been heated on a stove.

B. Thermal with FLIR's MSX turned on.

* what are you seeing is a thermal smear of the coin as I tried to relocate the coin to the center.

 

[Tim Jones]

Interesting
So would thermal be a better application to identify the object of a shark in sallow water, or would AI in image recognition be better.
Sharks are cold blooded and may actually not have a heat signature like a mammal. Though I am sure swimming must take energy and energy usually means heat

I am honestly just thinking out loud here. But as a Diver and Beach Lover ... Arrrr
it occurs to me a service that might make sense is periodic drone surveillance of popular beaches that have a history of shark attacks.
I know in Australia they have large networks of netting off beaches in an attempt to prevent shark attacks. But that has to be costly.
Just wondered if there was a potential business model there, and could thermal play a role

 

[Outta Control]

Interesting
So would thermal be a better application to identify the object of a shark in sallow water, or would AI in image recognition be better.
Sharks are cold blooded and may actually not have a heat signature like a mammal. Though I am sure swimming must take energy and energy usually means heat...

yes everything emits thermal radiation. It just need to break the thermal equilibrium to make it easier for identification. That my friend is ...

https://hopetheanchorformysoul.files.wordpress.com/2015/09/that-is-why-you-fail-yoda.gif

j/k

 

[BigAl07]

There was a video made by Jon McBride (I think it was Jon) of someone in water and it showed just how quickly the water reduces the heat signature.

 

[Outta Control]

There was a video made by Jon McBride (I think it was Jon) of someone in water and it showed just how quickly the water reduces the heat signature.

Yeah Jon is my buddy. He is spearheading some great thermal video applications but now he is doing more custom sUAS build.

As faint the thermal signature may be, as long as the target is generating heat and is not close to thermal equilibrium, then only through the eyes of an experienced (note I did not say certified) thermographer can spot this.

 

[MadProps]

Thanks for posting this! I don't have anything to add, but this is great information for us trying to learn all we can about thermal imaging.

 

[AIA.AI]

Thanks for posting @OuttaControl. This is one side of the sUAV applications, that im completely unfamiliar with. It's very intriguing....and your knowledge in the subject matter is impressive! thanks again for share