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Comment by oppositelock | Hacker News Reader

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-flig...)

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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)

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

I've seen larger aberrations from satellite captures of planes. But I've no idea how to estimate height or speed by that.

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.

Aha! Here we go. Here's a telephone pole: 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.

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

Probably headed to Whiteman AFB. Here's one parked: https://www.google.com/maps/place/38%C2%B043'29.7%22N+93%C2%...

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.

For those interested, here is the shadow: 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.

Thanks! It's conveniently hidden by a grassy area and some trees which throw shadows of their own. Actually, I should be doing something more useful at the moment...

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.

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