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Men rescued from Pacific island after writing SOS in sand

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Re: Men rescued from Pacific island after writing SOS in sand

#71

Post by [deleted] »

ohazi wrote: post #66
throwaway5752 wrote: post #64

Earlier quoted context omitted.

I'm not trying to take this discussion in a bad direction, but we're seeing a society-wide failure in the US to wear small pieces of cloth over our face to reduce the transmission of a serious illness. People frequently fail to prepare adequately even when given the means and opportunity. Search and rescue scenarios are not always for people that planned around getting lost and have a locator beacons on their person.…

I'm trying to fight the perception that PLBs are expensive specialty gadgets meant for professional explorers [1]. They should be considered as basic and as necessary as a life vest, seat belt, or bike helmet. You should not be backpacking on the Appalachian trail without one. [1] https://news.ycombinator.com/item?id=24065435

[deleted]

Re: Men rescued from Pacific island after writing SOS in sand

#73

Post by saeranv »

thaumaturgy wrote: post #39
throwaway5752 wrote: post #4

Call this a freely given and viable but hard to monetize idea - this is a very tractable area for software and drones. Same with locating people in lost wilderness areas. You have a programmatic way to organize coverage areas, you have access to above-human audio and video capabilities, and it reduces the resources/time ratio that is critical in rescues. This was the tragic and avoidable story that convinced me this…

This does not work well in practice, yet. There is a lot of interest already in using both off-the-shelf and more purpose-built drone technologies in search and rescue. They currently have too many limitations: they cannot navigate complex tree canopies close enough to the ground to provide reliable visual contact with subjects; their flight time is so limited that deployment and management is a real pain for large s…

> Thermal imaging likewise just does not work the way that people think it does. It doesn't work in cold environments like the Sierra in winter (western or eastern), because people are typically wearing insulated clothing and the entire area around them is a gigantic heat sink. It also doesn't work in very warm environments or in heavily vegetated environments or rocky environments with sunlight -- rocks absorb and re-radiate heat and so do plants.

I wonder if there's a specific subset of this problem domain where thermal imaging could be very useful: detecting campfires at night.

I think this would address the limitations you mention, primarily due to the extreme temperature difference between the fire and surroundings. Since the night sky has a high absorptance to emittance ratio and thus acts as a thermal sink, the surrounding tree canopy would be cool and increase the contrast more.

Of course, fire would have a high contrast with its surroundings even in the visible light range, so perhaps I am overthinking this. One possible advantage of thermal imaging though would be if the convective heat transfer as the hot air moves up could act as a sort of long-range beacon? Possibly not because I know any particles in the air, or water vapor will reflect/obstruct thermal radiation over long distances and prevent it from being seen clearly.

Re: Men rescued from Pacific island after writing SOS in sand

#74

Post by Scoundreller »

p1mrx wrote: post #70
aaron-santos wrote: post #26

Earlier quoted context omitted.

At 10m resolution and ~5day revisit time, it might be possible to optimize for satellite detection. Smoke is relatively easy to spot in satellite imagery. This may be one's best bet. It's also important to note that fires (anything hot really) is also easily detectable. 30-40m high burning SOS letters would be an interesting strategy. One of the things to keep in mind is that for Sentinel-2 the mean local solar time…

It would be difficult to keep text burning for days on end. You're probably better off writing SOS in high contrast, with a regular fire nearby.

Could work against you if the updated images get filtered out under the cloud cover/fog category.

Re: Men rescued from Pacific island after writing SOS in sand

#75

Post by Alupis »

hluska wrote: post #62
Alupis wrote: post #48

Earlier quoted context omitted.

Tough choices have to be made in Rescue teams all the time. Another comment pointed out above that SAR teams routinely abandon searches when it becomes too hazardous. Trading one or more human lives for another isn't worth it in many cases. We do value human life more than animals. This is non-debatable for sure. However, at some point the costs of pursuing a rescue might be outweighed by other factors - one of which…

I’ve got to compliment you. This is one of the better conversations that I’ve had online in a very long time. You’re a big part of why this has been so enjoyable. Thanks for the fun and for raising so many good points. I was a lot more certain before I started reading you and now I’m not sure. Big respect and thanks again. If you’re interested, here’s an absolute nightmare scenario that actually happened. People were…

A spirited debate now and again is good for the brain. :)

It challenges your thoughts and positions, and makes you actually question and rationalize why you think the things you do.

On occasion, you realize you were wrong. On other occasions, it enables you to fully develop your thoughts and prepare to rationally support them.

Either way, it's healthy, and far preferred to being in an echo chamber hearing only your own thoughts.

Thanks for taking the time to participate.

Re: Men rescued from Pacific island after writing SOS in sand

#76

Post by throwaway0a5e »

ohazi wrote: post #66
throwaway5752 wrote: post #64

Earlier quoted context omitted.

I'm not trying to take this discussion in a bad direction, but we're seeing a society-wide failure in the US to wear small pieces of cloth over our face to reduce the transmission of a serious illness. People frequently fail to prepare adequately even when given the means and opportunity. Search and rescue scenarios are not always for people that planned around getting lost and have a locator beacons on their person.…

I'm trying to fight the perception that PLBs are expensive specialty gadgets meant for professional explorers [1]. They should be considered as basic and as necessary as a life vest, seat belt, or bike helmet. You should not be backpacking on the Appalachian trail without one. [1] https://news.ycombinator.com/item?id=24065435

How would you feel about a $300 fee to use the national parks?

If a PLB is required in all but law then that's almost the same effect. IMO that kind of goes against the spirit of having national parks and other purposely undeveloped areas.

Sure it would be nice if everyone had one but I don't wanna make hiking and camping, which can be very cheap ways to recreate if you want them to be, instantly $300 more expensive.

Re: Men rescued from Pacific island after writing SOS in sand

#77

Post by throwaway0a5e »

throwaway5752 wrote: post #14
Alupis wrote: post #9

Earlier quoted context omitted.

Or... a dude in a helicopter with FLIR? Sometimes, low tech is best, honestly. Of course they already have that. The problem isn't coverage usually, it's density of the terrain features and vegetation, and an unknown search radius in some cases. That, and unprepared people with no way to signal a search vehicle if one comes near. That's a human problem though, not a tech problem.

Sure. It's the unknown search radius, availability of pilots, human factors, as well as the greater ability of a drone to self (or with human intervention) track in to greater resolution that makes me wonder if this is doable. Get the helicopter with a flir camera, but also send out 50 quadcopters or uavs as a force multiplier. If there is some sort of interesting infrared or acoustic signature at a site, just log it…

>but also send out 50 quadcopters or uavs as a force multiplier.

Random small aircraft with FLIR on a swivel mount that beams the results back to somewhere else for analysis would likely be more cost effective for equivalent coverage.

Re: Men rescued from Pacific island after writing SOS in sand

#78

Post by jjav »

jcrawfordor wrote: post #34
ghaff wrote: post #24

Earlier quoted context omitted.

It’s a satellite commS device. You also need a service for it to be useful. I do find it somewhat amusing to read a comment that a device that locates me anywhere on the planet and can communicate that information via satellite costs a few hundred dollars! to be vaguely amusing.

There are really two different options here. Some devices, variously called EPIRBs, PLBs, and ELTs depending on the exact device and application, report to a system called COSPAS-SARSAT which is a free service operated by an international collaboration. You do not need to pay any service fee for these, although you are required to register them with a local authority (the Coast Guard in the US) so that they have cont…

> ...mostly GlobalStar. Spot X and Garmin InReach are the two big ones

These are different though. SPOT works on globalstar which has gaps in coverage, particularly large parts of the Pacific. A coverage map is here: https://www.findmespot.com/en-us/products-services/coverage-...

The inReach works on iridum and claims 100% world-wide coverage.

Personally I carry an EPIRB for the boat, a PLB on the lifejacket and an inReach for texting. Cheap insurance.

Re: Men rescued from Pacific island after writing SOS in sand

#80

Post by squarefoot »

jessriedel wrote: post #20
vosper wrote: post #15

Earlier quoted context omitted.

They're not even expensive to buy. I picked one up for a few hundred dollars for hiking. I believe it's good for 10 years, until the battery needs replacing. I don't even do particularly intense hikes, usually not even overnight, but I read a few stories and realised how easy it is to end up in a situation where you need one. You just have to slip over and land badly, that's all it takes. Or maybe it won't be me, but…

A few hundred dollars seems fastastically expensive to me. What is possibly inside it that justifies that price?

It's a safety device; it must work reliably in adverse conditions, which is a requirement no consumer device, including €5000 TV sets, can meet. Also I believe in case of failure it would expose the manufacturer to some nasty lawsuits, hence the cost which very likely is equally spread on research, top notch build, quality control and insurance.
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