3 ms·

I am more amazed at the lack of smog blocking visibility. Disclaimer: I'm Chinese and I love Beijing as a city, on a good day it's about as clean as LA and on

I am more amazed at the lack of smog blocking visibility. Disclaimer: I'm Chinese and I love Beijing as a city, on a good day it's about as clean as LA and on a bad day its...well you can barely see airport terminal when you land.

digikata 13y ago
In LA at least, smog goes to about 5000ft to the inversion layer. Looking vertically through that distance you get much better visibility vs looking horizontally through miles of smog. You can notice the effect looking out a plane window at cruise altitude compared to landing and takeoff.
- celoyd 13y ago
  Exactly. This is why distant city lights often twinkle even more than stars do: there’s more atmosphere between you and them than between you and the stars. Another effect here is that Skybox’s video uses the pan band, which includes infrared to 900 nm[0], and smog is usually pretty transparent in NIR, depending. 0. http://skybox.com/uploads/10/08/imageryandvideospecsheet.pdf http://skybox.com/uploads/10/08/imageryandvideospecsheet.pdf And a third important factor is that smog is very diffuse (by definition: otherwise you call it a smoke plume), so if you have the bit depth you can just increase contrast until you get a good image. (I work at Mapbox on satellite imagery, but wasn’t involved with this particular blog post; what I’m saying here is stuff that people in remote sensing Just Know.)
- elwell 13y ago
  and: "west la" != "central la"
nysv 13y ago
It could be using a wavelengths that go through smog.
- PakG1 13y ago
  That'd be interesting, given this article I saw a while back: http://www.scmp.com/news/china/article/1347835/security-fears-china-surveillance-cameras-are-blinded-thick-smog?page=all http://www.scmp.com/news/china/article/1347835/security-fear... Professor Yang Aiping, an expert in digital imaging with the School of Electronic Information Engineering of Tianjin University and leader of the civilian team, said she was facing tremendous pressure because of the enormous technological challenges. "Most studies in other countries are to do with fog. In China, most people think that fog and smog can be dealt by the same method. Our preliminary research shows that the smog particles are quite different from the small water droplets of fog in terms of optical properties," she said. "We need to heavily revise, if not completely rewrite, algorithms in some mathematical models. We also need to do lots of computer simulation and extensive field tests."

digikata 13y ago

In LA at least, smog goes to about 5000ft to the inversion layer. Looking vertically through that distance you get much better visibility vs looking horizontally through miles of smog. You can notice the effect looking out a plane window at cruise altitude compared to landing and takeoff.

celoyd 13y ago
Exactly. This is why distant city lights often twinkle even more than stars do: there’s more atmosphere between you and them than between you and the stars. Another effect here is that Skybox’s video uses the pan band, which includes infrared to 900 nm[0], and smog is usually pretty transparent in NIR, depending. 0. http://skybox.com/uploads/10/08/imageryandvideospecsheet.pdf http://skybox.com/uploads/10/08/imageryandvideospecsheet.pdf And a third important factor is that smog is very diffuse (by definition: otherwise you call it a smoke plume), so if you have the bit depth you can just increase contrast until you get a good image. (I work at Mapbox on satellite imagery, but wasn’t involved with this particular blog post; what I’m saying here is stuff that people in remote sensing Just Know.)
elwell 13y ago
and: "west la" != "central la"

nysv 13y ago

It could be using a wavelengths that go through smog.

PakG1 13y ago
That'd be interesting, given this article I saw a while back: http://www.scmp.com/news/china/article/1347835/security-fears-china-surveillance-cameras-are-blinded-thick-smog?page=all http://www.scmp.com/news/china/article/1347835/security-fear... Professor Yang Aiping, an expert in digital imaging with the School of Electronic Information Engineering of Tianjin University and leader of the civilian team, said she was facing tremendous pressure because of the enormous technological challenges. "Most studies in other countries are to do with fog. In China, most people think that fog and smog can be dealt by the same method. Our preliminary research shows that the smog particles are quite different from the small water droplets of fog in terms of optical properties," she said. "We need to heavily revise, if not completely rewrite, algorithms in some mathematical models. We also need to do lots of computer simulation and extensive field tests."