For the military types.. thermal imaging:

[Connor MacLeod]

I've got a question. How good is thermal imaging at detecting people in the daytime (say midmorning to afternoon)? (and how heavily does it depend on other factors such as terrain and the like? IE tundra vs forest vs desert.)

Are there any other limitations with daytime thermal imaging as well?

[Admiral Valdemar]

As good as night for most high-end, second-gen systems. The cops round here use FLIRs on the helos to search for people in daytime and night, but normally it's never needed for daylight ops. So long as no massive IR source is bleaching the image, you can detect anything with a thermal signature.

[defanatic]

Is the sand in a desert hotter than people?

Just a question, and I'm also making an assumption about where people would be fighting.

[Admiral Valdemar]

That shouldn't matter. If the people are cooler than the surroundings, then there is a difference in temperature, which can readily be detected.

[Darth Wong]

That shouldn't matter. If the people are cooler than the surroundings, then there is a difference in temperature, which can readily be detected.

There are plenty of places in the world where the ambient temperature can be as high as human body temperature or even higher. Did you know that the pseudo-infrared PredatorVision effect used in the movie Predator was not the director's first choice? They initially tried using real infrared imaging, but the men didn't stand out against the hot Mexico jungle.

[Admiral Valdemar]

There are many systems out there, but typically, the ones the military uses are like the cop ones, albeit, more advanced. The black and white monochromatic imagery is good for finding targets quickly, while the coloured systems are often used by engineers and scientists to assess thermal energy at precise levels. For Predator, they'd likely be using generation one civilian stuff anyway, so the resolution would be pretty limited. At least today, you're more likely to differentiate humans from boiling jungle by movement as well as slight temperature differences from sweat etc. given modern systems have Minimum Resolvable Temperature Difference (MRTD) tolerances around millikelvins for cooled optics especially.

A lot of goggles that are IR merely emit an IR beam to light up the background invisibly, rather than actually measure thermal signatures. Still, for the military, you can get software that will look out for certain types of heat signature and match it with possible targets, much like new phased array radars have a resolution able to ID aircraft from shape, not just engine inlet returns.

[Connor MacLeod]

There are many systems out there, but typically, the ones the military uses are like the cop ones, albeit, more advanced. The black and white monochromatic imagery is good for finding targets quickly, while the coloured systems are often used by engineers and scientists to assess thermal energy at precise levels. For Predator, they'd likely be using generation one civilian stuff anyway, so the resolution would be pretty limited. At least today, you're more likely to differentiate humans from boiling jungle by movement as well as slight temperature differences from sweat etc. given modern systems have Minimum Resolvable Temperature Difference (MRTD) tolerances around millikelvins for cooled optics especially.

You seem to be mainly referring to urban settings, however. But I'm still wondering if other terrain might influence this. As Mike noted, plants (like in a jungle) seem to be fairly significant IR sources,a nd from what I've seen/read they can interfere with systems as well. In a jungle setting, I'd also have to wonder if thick undergrowth or dense tree grgowths would interfere with "imaging" unless you were very very close. That would also affect the whole "motion-based" detection" (Isn't motion detection a separate detection system anyhow?)

A lot of goggles that are IR merely emit an IR beam to light up the background invisibly, rather than actually measure thermal signatures. Still, for the military, you can get software that will look out for certain types of heat signature and match it with possible targets, much like new phased array radars have a resolution able to ID aircraft from shape, not just engine inlet returns.

That would be more of an active sensing mechansim, wouldnt it? As an active sensor, I imagine it would be limited by line of sight (obstructions and such.)

[Ender]

I know sony released a video camera whose IR sensor was so good it could see through clothes in the day. They had to recall and rerelease one that wouldn't work if it was light out.

[Admiral Valdemar]

You seem to be mainly referring to urban settings, however. But I'm still wondering if other terrain might influence this. As Mike noted, plants (like in a jungle) seem to be fairly significant IR sources,a nd from what I've seen/read they can interfere with systems as well. In a jungle setting, I'd also have to wonder if thick undergrowth or dense tree grgowths would interfere with "imaging" unless you were very very close. That would also affect the whole "motion-based" detection" (Isn't motion detection a separate detection system anyhow?)

Third gen FLIRs would likely have the resolution to help pick out anomalies in a heat source. For all the heat of the jungle, the human body is not all absolutely set at 37 degrees. It will fluctuate, even to the point that sweat and organs could be picked out or personal items with obviously artificial signatures. There were systems used against the NVA quite well and modern day A-stan and Iraq where the ground can give off tremendous heat too. The undergrowth doesn't work to your advantage, but getting some ability to see is better than nothing. With reference to motion detection, I meant that as in pattern recognition of moving heat sources to alert human operators, like the systems used in urban CCTV. A hot clump of foliage will be easier to dismiss than a human shaped disturbance moving around.

To be honest, despite the shrinking down and advancement of such systems, I think you'd be far better with T-ray or ground penetrating radar for locating targets. No military uses just one sensor type, so using everything from the Mk. I Eyeball to MAD and SADAR ultrasonics is useful if someone is trying to evade one sensor type.

There are artificial sensor nets being developed here and in the US that consist of aerially scattered MEMS with various sensors from sound to EM to mass to pheremone. Littering these around an area in the future battlefield (each system no bigger than a couple centimetres square) will aid in durable battlefield intelligence.

That would be more of an active sensing mechansim, wouldnt it? As an active sensor, I imagine it would be limited by line of sight (obstructions and such.)

That's mainly used for covert night-vision when ambient light is too limited. The advantage is that it's like using a torch that the enemy can't see. Of course, this relies on the enemy's inventory, so if they have IR sensors, they'll see you. It's the same method used for covert nocturnal animal tracking as well.