4 ms·

The B2 bomber photo isn't from a push boom sensor, because it would be distorted since it's moving relative to the camera. This would manifest itself as a shear

The B2 bomber photo isn't from a push boom sensor, because it would be distorted since it's moving relative to the camera. This would manifest itself as a shear along the motion vector . There is no shear in this photo, only spectral bands. I've spent a number of years doing image orthorectification, and satellite imagery post-processing, then also worked on Google Earth and Google Maps, so I can tell you precisely what happened. This is a satellite image from a satellite which photographs different spectra at different times. There isn't enough parallax at typical orbital distance for this much displacement to come from multiple cameras. Looking at some parked cars, this looks like 20-30cm resolution per pixel, which is consistent with the newer earth imaging satellites. Google Earth made a blog post about this a while ago (https://www.gearthblog.com/blog/archives/2015/03/planes-flight-rainbow-effect.html https://www.gearthblog.com/blog/archives/2015/03/planes-flig...)

kloch 5y ago
If it’s anything like space telescopes there are more than 3 spectral filters that can be selected which rules out a static Bayer-type filter system.
bpye 5y ago
Shame we don't know what the delay between spectra is, would be fun to work out how fast the plane is traveling.
- dalmo3 5y ago
  I've seen larger aberrations from satellite captures of planes. But I've no idea how to estimate height or speed by that.
  - oppositelock 5y ago
    You can get height if you can find the shadow, and find the time that the photo was taken, because at any given time and date, you can compute sun position, and you know the precise lat/lng of the shadow. The shadow would need to be in the same photo, though. (actually, it's a bit to the northwest, just found it). If you can find a vertical structure, like an antenna mast, you can measure shadow length and direction and if you know the height of the antenna, you have enough information for some trigonometry. Speed is harder. You'd need to know the difference between exposures.
    - oppositelock 5y ago
      Aha! Here we go. Here's a telephone pole: https://earth.google.com/web/search/39.0303298,-93.58495/@39.0303223,-93.58490691,230.87707932a,67.38914248d,35y,351.22667355h,0t,0r/data=CigiJgokCfFGDVg6ZERAEaGjgcDYWkRAGSWqyHhIeFLAIXtTdN2bf1LA https://earth.google.com/web/search/39.0303298,-93.58495/@39... We know that telephone poles stick about 32 feet from the ground. Measuring the shadow in Google Earth above, it's about 20 feet. Now, it's a simple ratio. Using Earth, I measured the distance from the plane to its shadow at about 2430 feet, that would put it at 3,900ft, which is surprisingly low, but I don't know the height of that pole for sure. It's the right ballpark, though.
      - mountainofdeath 5y ago
        The B2 is based out of Whiteman AFB near Warrensburg, MO so roughly 25 miles or 40 km south of where the plane is so it is probably on its final approach to land or just took off.
      - abrowne 5y ago
        Not too low if landing? From another comment: > This one was probably on final approach during the summer when the winds are usually out of the south and was probably about 2,000 feet above the ground. https://news.ycombinator.com/item?id=29628167 https://news.ycombinator.com/item?id=29628167
        rookderby 5y ago
        Probably headed to Whiteman AFB. Here's one parked: https://www.google.com/maps/place/38%C2%B043'29.7%22N+93%C2%B033'36.9%22W/@38.7249302,-93.5608583,265m/data=!3m2!1e3!4b1!4m6!3m5!1s0x0:0xcb5e5c0d39e9ba83!7e2!8m2!3d38.7249291!4d-93.5602414 https://www.google.com/maps/place/38%C2%B043'29.7%22N+93%C2%...
    - ryan_j_naughton 5y ago
      For those interested, here is the shadow: https://www.google.com/maps/place/39%C2%B001'28.8%22N+93%C2%B036'08.3%22W/@39.0246612,-93.6028455,228m/data=!3m2!1e3!4b1!4m5!3m4!1s0x0:0x53a2425e36cc7fce!8m2!3d39.0246602!4d-93.6022983 https://www.google.com/maps/place/39%C2%B001'28.8%22N+93%C2%... Took me a while to find it, so thought I'd save someone else the scrolling/search cost.
jcims 5y ago
Agree it wouldn’t be parallax from multiple cameras on the same satellite but the delay between images seems quite short for physical filter swapping (~20ms per filter). (Edit: Actually DLP does it in about that amount of time, nvm)

kloch 5y ago

If it’s anything like space telescopes there are more than 3 spectral filters that can be selected which rules out a static Bayer-type filter system.

bpye 5y ago

Shame we don't know what the delay between spectra is, would be fun to work out how fast the plane is traveling.

dalmo3 5y ago
I've seen larger aberrations from satellite captures of planes. But I've no idea how to estimate height or speed by that.
- oppositelock 5y ago
  You can get height if you can find the shadow, and find the time that the photo was taken, because at any given time and date, you can compute sun position, and you know the precise lat/lng of the shadow. The shadow would need to be in the same photo, though. (actually, it's a bit to the northwest, just found it). If you can find a vertical structure, like an antenna mast, you can measure shadow length and direction and if you know the height of the antenna, you have enough information for some trigonometry. Speed is harder. You'd need to know the difference between exposures.
  - oppositelock 5y ago
    Aha! Here we go. Here's a telephone pole: https://earth.google.com/web/search/39.0303298,-93.58495/@39.0303223,-93.58490691,230.87707932a,67.38914248d,35y,351.22667355h,0t,0r/data=CigiJgokCfFGDVg6ZERAEaGjgcDYWkRAGSWqyHhIeFLAIXtTdN2bf1LA https://earth.google.com/web/search/39.0303298,-93.58495/@39... We know that telephone poles stick about 32 feet from the ground. Measuring the shadow in Google Earth above, it's about 20 feet. Now, it's a simple ratio. Using Earth, I measured the distance from the plane to its shadow at about 2430 feet, that would put it at 3,900ft, which is surprisingly low, but I don't know the height of that pole for sure. It's the right ballpark, though.
    - mountainofdeath 5y ago
      The B2 is based out of Whiteman AFB near Warrensburg, MO so roughly 25 miles or 40 km south of where the plane is so it is probably on its final approach to land or just took off.
    - abrowne 5y ago
      Not too low if landing? From another comment: > This one was probably on final approach during the summer when the winds are usually out of the south and was probably about 2,000 feet above the ground. https://news.ycombinator.com/item?id=29628167 https://news.ycombinator.com/item?id=29628167
      - rookderby 5y ago
        Probably headed to Whiteman AFB. Here's one parked: https://www.google.com/maps/place/38%C2%B043'29.7%22N+93%C2%B033'36.9%22W/@38.7249302,-93.5608583,265m/data=!3m2!1e3!4b1!4m6!3m5!1s0x0:0xcb5e5c0d39e9ba83!7e2!8m2!3d38.7249291!4d-93.5602414 https://www.google.com/maps/place/38%C2%B043'29.7%22N+93%C2%...
  - ryan_j_naughton 5y ago
    For those interested, here is the shadow: https://www.google.com/maps/place/39%C2%B001'28.8%22N+93%C2%B036'08.3%22W/@39.0246612,-93.6028455,228m/data=!3m2!1e3!4b1!4m5!3m4!1s0x0:0x53a2425e36cc7fce!8m2!3d39.0246602!4d-93.6022983 https://www.google.com/maps/place/39%C2%B001'28.8%22N+93%C2%... Took me a while to find it, so thought I'd save someone else the scrolling/search cost.

jcims 5y ago

Agree it wouldn’t be parallax from multiple cameras on the same satellite but the delay between images seems quite short for physical filter swapping (~20ms per filter). (Edit: Actually DLP does it in about that amount of time, nvm)