A new camera can photograph from 45 kilometers away | Hacker News Reader

A new camera can photograph from 45 kilometers away

technologyreview.com

94 pointsjonbaer34 comments

Range gated imagers have been around for at least 15 years. Here are some videos from a US manufacturer at various ranges.[1]

These things are good at seeing through fog, smoke, dust, and camouflage nets. The best ones are military and tend not to be talked about much.[2]

[1] http://www.obzerv.com/en/videos/

[2] http://www.sensorsinc.com/applications/military/laser-range-...

Operating principle: http://new-imaging-technologies.com/data/company/311894/file...

Core idea is to use a pulsed laser and extremely short exposures such that the sensor is only exposed to light that travelled a given distance range, hence range-gated.

Haha, I think you forgot a "you" in the title. I can photograph the moon from 300,000 km away with my phone.

If you can photograph Cassiopeia, one of those is 4000ly away.

On that note, it isn't too difficult to photograph M31, the Andromeda Galaxy, at roughly 2.5 Mly.

> The results speak for themselves. The team set up the new camera on the 20th floor of a building on Chongming Island in Shanghai and pointed it at the Pudong Civil Aviation Building across the river, some 45 km away.

The image right beneath this paragraph [0] contradicts it. Does anyone know the reason for this discrepancy?

[0] https://cdn.technologyreview.com/i/images/single-pixel-imagi...

Interesting image. With 2 minutes of fiddling with Levels tool of Paint .NET I can resolve c) to the level of details from e) / f). The necessary bits of information about the object are already present in c).

EDIT: https://static.mastodon.technology/media_attachments/files/0....

I know it’s common and frowned on to comment on the site rather than the content, but wow.

The content on that site takes up a bit less than one third the screen on an iPhone 8. The rest is the cookies policy and the subscription advert. It’s totally obnoxious.

Agreed, you hate to see a dumpster fire like this with MIT's name on it.

Since we’re already off-topic here, what is the point of all of these “read the rest” squishings of content? If you click “read all”, they always seem to display the content immediately meaning it isn’t doing an additional load to get the text meaning they aren’t “saving bandwidth” by not loading content people won’t read. It’s obviously just hidden via css. I don’t get the purpose...especially since as op mentioned there already is so much cruft.

You could track if users actually try to read the rest of the article.

Ah ok yeah, that makes some sense. Thanks!

Is it not possible for the page to track how far down it has been scrolled? (I've seen plenty of pages that react to scrolling)

What does the action of clicking on a button add?

Yes, it is possible, but bear in mind that this site has an infinite scrolling behaviour, so you could actually scroll down and be reading another article. Then you would have to keep track of the height of each article and account for font sizes and many other things.

It is doable, but not usually worth the hassle imo. Plus it is a somewhat common thing on many other sites.

>But the new technique produces images with a spatial resolution of about 60 cm, which resolves building windows. “This result demonstrates the superior capability of the near-infrared single-photon LiDAR system to resolve targets through smog,” say the team. //

Awesome stuff. It is 'only' an incremental improvement over the other algos listed there though (which I wasn't aware of).

Gated photography with pulsed laser illumination for surveillance isn't exactly new; there are quite a few companies in the US that sell it to law enforcement / military.

And 27 miles isn't a big deal absent the smog...

Since when is a 120 mW laser eye safe?

yah, that's a bit scary. 120mW infrared laser touted as eye safe...what could go wrong?

I'm guessing it has to do with how the beam is focused though. theoretically I think it could be eye safe at close range.

The laser is pulsed at 100khz. A low duty cycle would make it more eye-safe, and increase the z resolution.

Found this, which seems to go some way toward explaining it - http://www.fsona.com/product.php?sec=safety

Presumably when you get down to 1550 nm, the transmission of light through the lens is a lot lower.

The eye safety limit for 1550 nm is thousands of times higher than for visible light or near infrared. https://commons.wikimedia.org/wiki/File:IEC60825_MPE_J_nm.pn...

> thousands of times higher

Didn't you mean "lower"? Which unit are we talking about here?

Probably power?

Deceiving clickbait for interesting technology. This is nothing like 'photography':

> Developed in China, the lidar-based system can cut through city smog to resolve human-sized features at vast distances.

> the new technique produces images with a spatial resolution of about 60 cm, which resolves building windows

And it is not bending beyond the horizon but simply mounted on high location.

"Photography is the art, application and practice of creating durable images by recording light or other electromagnetic radiation"

L(!)idar: Laser (photons)

I'm really struggling to find any alternative headline. It's almost anti-clickbait ("click-scarecrow" is the most creative I can come up with using a dictionary). Because it essentially gives away the most important details of the story.

The term "clickbait" has just outlived it's usefulness when it's applied to any and every headline someone doesn't like for whatever reason. To show the difference, here are some alternative, actual-clickbait, headlines:

- Naked Sunbathing? Better hope nobody in a 45-mile radius has this new invention!

- This new technology could turn your iPhone into a superspy!

- Soon, governments will be able to spy on you picking your nose alone in the middle of a desert

- 11 reasons to stay indoors, number 11 even surprised us!

'Camera' and 'photograph'. Did you really not expect something more like a traditional photo?

Reads to me more like the "lidar" mention is misleading, since the goal isn't range finding.

The way I read it they probe for a certain range whether there is reflection or not. So the result will be like range finding.

The evidently terrible Chinese pollution levels distract from the cool tech. A nighttime photo might be more interesting assuming the subject was too far away to simply illuminate with IR - but in that case perhaps you just use a very long exposure?

The real story here is the fact that you can you photograph a building from 45 km away proves that the earth is flat. ;-)

Well, any camera can photograph from any distance ...

"...assuming the camera is mounted high enough off the ground to cope with Earth’s curvature"

Erm, without getting into THAT discussion; wouldn't this be the case even if the plane was completely flat due to perspective? You know, things further away tend to get smaller and disappear behind closer features.

What disappears due to curvature is more or less lost, I can't see building a higher tower helping much.

Edit: Can't even mention curvature without being hell-voted. I'll just note that I'm not the one with issues here, I posed an honest question about a technical detail.

Please don't break the site guidelines, which ask you not to comment about the voting on comments. "It never does any good, and makes boring reading."

https://news.ycombinator.com/newsguidelines.html

You can't see that getting to a higher altitude counteracts the curvature of the earth?

Reply on news.ycombinator.com