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Bats slam into buildings because they can't 'see' them
- Isamu 9y agoI had read this as Bots slamming into buildings, and was looking for a discussion of lidar and stereo vision systems. But won't lidar have the same issue, with a clean glass surface? Similar with stereo vision - if there are no features at the surface to correlate.
- emeijer 9y agoVision based on visible light doesn't suffer from the problem in the same way as echolocation or lidar, since it is not dependant on observing signals emitted by the observer. I guess very smooth surfaces might act as mirrors, which will probably bring it's own set of difficulties for machines. Anecdotally, I can say my own stereo vision doesn't have big difficulties with most smooth surfaces though :)
- bighi 9y agoBut bats also use vision based on visible light. I haven't read the article yet, but do they explain about why the bat wouldn't see the building with its eyes?
- marcosdumay 9y agoI know I have slammed into transparent surfaces because I couldn't see them. It probably gets worse the higher you go, because there is less grassy people adding marks to them, and less "people are hitting this too much, we'd better reduce that glass size". Birds are famous for getting them wrong.
- robotresearcher 9y agoYes, lidar bounces off surfaces at shallow angles to give false readings. Also, the long wavelength of IR means that lots of flattish surfaces are good mirrors. In mobile robotics, glass panelled corridors are perceived very badly.[1] Passive depth from stereo usually has big holes where no features are detected[2]. That's why Kinect and the like project their own IR texture into the scene. Outdoors ambient IR overwhelms the projection unless you use powerful lasers. The upshot of this is that robots are vulnerable to banging into stuff, like bats. [1] I don't know for sure but it's likely that the right hand side of this map I found online has glass walls causing bad range data: https://i.pinimg.com/originals/e0/87/04/e08704b6dc925b575c2f1fe15e92be84.jpg https://i.pinimg.com/originals/e0/87/04/e08704b6dc925b575c2f... [2] If it doesn't, it's because the holes have been filled by interpolation - guessing what is there rather than observing it directly.
- grondilu 9y agoThat made me wonder how bats see water surfaces. Though I suppose not seeing them is less of a problem since they're not vertical :P
- SeanDav 9y agoThis is a good point. Perhaps the sound penetrates a distance into the water and you get scattering, returning a small signal.
- maxxxxx 9y agoReal life water surfaces are probably not as smooth as glass windows. Just a guess.
- ethomson 9y agoThe post explains this: they don't. Standing water exhibits the same behavior as reflectiveless flat surfaces. When they fly over a space and "see" nothing beneath them, they interpret this emptiness as a flat, smooth body of water. Thus the only real problem here is that for flat horizontal surfaces that aren't water, the bats will try to drink from them.
- sailfast 9y agoInteresting hypothetical to track bat evolution in urban areas over time to determine if selection is occurring for bats whose sonar is more finely attuned for detecting diffused returns as actual signal for skyscrapers or, for that matter, improved actual sight to avoid the buildings in the first place.
- peterwwillis 9y agoTIL Some Hawkmoths shoot ultrasound from their junk to thwart bat attacks. http://www.pnas.org/content/112/20/6407.full.pdf http://www.pnas.org/content/112/20/6407.full.pdf
- theoh 9y agoThis reminded me of (humor) http://www.mjt.org/exhibits/foundation_collections/depmori/depmori.htm http://www.mjt.org/exhibits/foundation_collections/depmori/d... "The key idea in the Griffith hypothesis was that as the Myotis lucifugus emission increased in frequency, the emission actually crossed the thresholds from the extreme ultraviolet into the X-ray, thereby allowing the bat to fly unharmed through solid objects."
- rashkin 9y agoI've heard bats are almost blind but they fly around using some type of signals in order to know where the objects are around them
- mwerd 9y agoPoor bats. They also get their lungs exploded by the pressure differences created near wind turbines: https://www.wind-watch.org/news/2016/09/27/wind-turbines-are-causing-bats-lungs-to-explode/ https://www.wind-watch.org/news/2016/09/27/wind-turbines-are...
- Retric 9y agoMeh, a 5 Mega Watt wind turbine kills less wildlife than the average outdoor cat.
- SeanDav 9y ago> "Meh, a 5 Mega Watt wind turbine kills less wildlife than the average outdoor cat." Do you have some sort of data to back this up?
- JadeNB 9y agoI imagine that Retric (https://news.ycombinator.com/item?id=15228800 https://news.ycombinator.com/item?id=15228800) is referring to stories like https://www.washingtonpost.com/national/health-science/outdoor-cats-kill-between-14-billion-and-37-billion-birds-a-year-study-says/2013/01/31/2504f744-6bbe-11e2-ada0-5ca5fa7ebe79_story.html https://www.washingtonpost.com/national/health-science/outdo... and https://www.nytimes.com/2014/03/22/opinion/sunday/the-evil-of-the-outdoor-cat.html https://www.nytimes.com/2014/03/22/opinion/sunday/the-evil-o... (DDG results for "outdoor cats wildlife death"), compared to, say, http://www.smithsonianmag.com/smart-news/how-many-birds-do-wind-turbines-really-kill-180948154 http://www.smithsonianmag.com/smart-news/how-many-birds-do-w... (DDG result for "wind turbine wildlife death"). This is likely unpopular (especially with cat people like me), but I'm not sure what's callous about it—unless you mean the "meh" part, in which case I'm not sure how backing it up with data makes it any less callous.
- Retric 9y agoThat's where the comparison comes from, however it's more that these articles are linking to harm without putting it into any perspective. If we replaced all electricity generation with wind farms you would kill fewer birds from pollution than the existing power plants directly kill. There are 10+ billion birds in the US and a smaller but very large number of bats and well over 1 billion of them die every year. Talking about hundreds of bird/bat deaths in that context is almost meaningless. PS: A fungus on the other hand is decimating bat populations and represents a real threat. However the actual threat is not exactly making the news. https://en.wikipedia.org/wiki/White-nose_syndrome https://en.wikipedia.org/wiki/White-nose_syndrome
- stcredzero 9y agoI hope someone doesn't use this as inspiration for an exploit against LIDAR. On second thought, I hope people do start working on an exploit, so engineers can get on with hardening systems against it!
- totalZero 9y agoThe use cases I know of for lidar don't usually include a glancing reflection off a large flat surface.
- stcredzero 9y agoColliding with a large angled piece of sheet material in the middle of a roadway doesn't sound pleasant.
- LeifCarrotson 9y agoWhile I agree that the sensor systems should image just about anything you can imagine, wouldn't a large angled reflective sheet produce a shadow that could be distinguished from normal road surfaces and avoided?
- stcredzero 9y agoThat's a good 1st cut. But if we review the prior art -- namely stage magic's tricks with mirrors -- what's to stop someone from putting something in the region of the reflected image that would be expected by the driving AI? So, if what's expected are bushes in the background, why not aim the mirror at other bushes at the right distance?
- ChuckMcM 9y agoI built a number of robots that use infrared distance sensors for object detection and collision avoidance. Sadly the stereo cabinet I had made myself and painted flat black appeared invisible to them. Several robots ran into the cabinet at full speed :-(. The mitigation was to add another sensor (ultrasonic) which was better at seeing solid surfaces (but same problem as the bats for off angle approach).
- amelius 9y agoI wonder how bats perceive the AT&T "Batman Building" in Nashville, TN. https://en.wikipedia.org/wiki/AT%26T_Building_(Nashville) https://en.wikipedia.org/wiki/AT%26T_Building_(Nashville)
- swighton 9y agoReminds me of a an anecdote about the F-117 Nighthawk which was the first stealth airplane nearly invisible to radar. Apparently the engineers working on it would come into the airplane hangers to find many dead bats as it was also invisible to sonar. Interestingly enough this made the engineers realize the stealth technology also could work for submarines which led to the IX-529 Sea Shadow stealth ship.
- sjtgraham 9y agoThe bats died because the radar absorbent material used on the F-117A was highly toxic.