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I don't follow why the drones need to go below the canopy at all. Just use an infrared camera! This is already being done in our local area for SAR, though with

I don't follow why the drones need to go below the canopy at all. Just use an infrared camera! This is already being done in our local area for SAR, though with remote controlled drones rather than autonomous[0], and it's worked. I also worked on a undergrad research project involving autonomously deployed drones that identified cattle with infrared and the results were a no-brainer compared to conventional cameras[1], even though this was quite a few years ago and both autonomous navigation and infrared options have gotten much much better since then. There's the problem of false positives for sure (e.g. deer), but it gives you more than enough starting points. This research sounds genuinely really fascinating, and I think they are making huge progress on a difficult problem (specifically, navigating unknown 3D space). I'm just not sure that this use case is the most important one. [0]: https://www.radionl.com/2018/03/11/3624/ https://www.radionl.com/2018/03/11/3624/ [1]: https://fosterelli.co/file/talk/tracking-cattle-with-infrared-imaging.pdf https://fosterelli.co/file/talk/tracking-cattle-with-infrare...

thaumaturgy 8y ago
I'd love to hear more about cases in which IR has made a difference in a search, because that hasn't been my experience or what I've heard about it. And I'm calling BS on IR being able to see footprints under fresh snow, unless that fresh snow is a light dusting about 1 cm thick -- which just about any tracker could follow anyway. IR requires a steep difference in thermal gradients between the subject and the environment. In cold environments, subjects tend to wear insulating clothing (and if they've shed that, then they've gone into the paradoxical undressing stage of hypothermia, and unfortunately they're done for). The cold environment also acts as a massive heat sink, quickly masking any heat signatures. Warm environments suffer from reflectivity. Rocks bake in the sunlight and then re-emit that radiation all night long. There are some environments where IR might help, but many more where it doesn't.
- chrisfosterelli 8y ago
  I don't know much personally about SAR applications. But in terms of the projects I've done, the temperature and size of the target is fairly predictable compared to noise in the image. While it's not as easy as "filter anything above this temperature as a positive", it's an easier engineering program than 3D navigation. > I'd love to hear more about cases in which IR has made a difference in a search, because that hasn't been my experience or what I've heard about it. Here's another link where IR was used to find seven missing people, same trial program: https://bc.ctvnews.ca/a-b-c-first-heat-seeking-drone-used-in-search-and-rescue-mission-1.3295797 https://bc.ctvnews.ca/a-b-c-first-heat-seeking-drone-used-in... While looking more into this though, they mentioned that one of the things the program found is that the drones are not good at seeing through tree canopies. This is surprising for me, and I suppose answers my question about why this MIT project has some benefit! I stand corrected in that regard. > There are some environments where IR might help, but many more where it doesn't. Absolutely. There's no magic solution for finding people. The project here is going to have pros and cons too, you need experienced people to know what tool makes sense where.
  - thaumaturgy 8y ago
    Thanks for the link. > *...one of the things the program found is that the drones are not good at seeing through tree canopies. This is surprising for me... Yeah, if you dig around a bit you can find infrared and near-infrared images of trees and forests, and overhead IR shots of forest canopies. Trees give off a surprising amount of IR.
closetohome 8y ago
Infrared is fine in open terrain or light forest, but it doesn't work nearly as well through a solid tree canopy.
- chrisfosterelli 8y ago
  Thanks, I looked more into this and agree you're correct here.
Pfhreak 8y ago
A person exposed to the elements will have a few characteristics that might make IR detection difficult: 1) A generally lowered body temperature from being wet/cold 2) Clothing or shelter designed to keep heat in or limit exposure to the elements (and therefore also cameras) 3) Trapped under rubble, landslides, snow, etc. that could obscure their IR signature. Granted, not in all cases, but I'd suggest that it's not quite as simple as just slapping an IR camera on a drone and flying it around.

thaumaturgy 8y ago

I'd love to hear more about cases in which IR has made a difference in a search, because that hasn't been my experience or what I've heard about it. And I'm calling BS on IR being able to see footprints under fresh snow, unless that fresh snow is a light dusting about 1 cm thick -- which just about any tracker could follow anyway. IR requires a steep difference in thermal gradients between the subject and the environment. In cold environments, subjects tend to wear insulating clothing (and if they've shed that, then they've gone into the paradoxical undressing stage of hypothermia, and unfortunately they're done for). The cold environment also acts as a massive heat sink, quickly masking any heat signatures. Warm environments suffer from reflectivity. Rocks bake in the sunlight and then re-emit that radiation all night long. There are some environments where IR might help, but many more where it doesn't.

chrisfosterelli 8y ago
I don't know much personally about SAR applications. But in terms of the projects I've done, the temperature and size of the target is fairly predictable compared to noise in the image. While it's not as easy as "filter anything above this temperature as a positive", it's an easier engineering program than 3D navigation. > I'd love to hear more about cases in which IR has made a difference in a search, because that hasn't been my experience or what I've heard about it. Here's another link where IR was used to find seven missing people, same trial program: https://bc.ctvnews.ca/a-b-c-first-heat-seeking-drone-used-in-search-and-rescue-mission-1.3295797 https://bc.ctvnews.ca/a-b-c-first-heat-seeking-drone-used-in... While looking more into this though, they mentioned that one of the things the program found is that the drones are not good at seeing through tree canopies. This is surprising for me, and I suppose answers my question about why this MIT project has some benefit! I stand corrected in that regard. > There are some environments where IR might help, but many more where it doesn't. Absolutely. There's no magic solution for finding people. The project here is going to have pros and cons too, you need experienced people to know what tool makes sense where.
- thaumaturgy 8y ago
  Thanks for the link. > *...one of the things the program found is that the drones are not good at seeing through tree canopies. This is surprising for me... Yeah, if you dig around a bit you can find infrared and near-infrared images of trees and forests, and overhead IR shots of forest canopies. Trees give off a surprising amount of IR.

closetohome 8y ago

Infrared is fine in open terrain or light forest, but it doesn't work nearly as well through a solid tree canopy.

chrisfosterelli 8y ago
Thanks, I looked more into this and agree you're correct here.

Pfhreak 8y ago

A person exposed to the elements will have a few characteristics that might make IR detection difficult: 1) A generally lowered body temperature from being wet/cold 2) Clothing or shelter designed to keep heat in or limit exposure to the elements (and therefore also cameras) 3) Trapped under rubble, landslides, snow, etc. that could obscure their IR signature. Granted, not in all cases, but I'd suggest that it's not quite as simple as just slapping an IR camera on a drone and flying it around.