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Line scan camera image processing for train photography

(daniel.lawrence.lu)
448 points dllu | 3 comments | 23 Aug 25 16:09 UTC | HN request time: 0s | source
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jeffbee ◴[23 Aug 25 20:10 UTC] No.44998743[source]▶
Okay I was stumped about how this works because it's not explained, as far as I can tell. But I guess the sensor array has its long axis perpendicular to the direction the train is traveling.
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miladyincontrol ◴[23 Aug 25 20:19 UTC] No.44998802[source]▶
Line scan sensors are basically just scanners, heck people make em out of scanners .

Usually the issue is they need rather still subjects, but in this case rather than the sensor doing a scanning sweep they're just capturing the subject as it moves by, keeping the background pixels static.

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1. krackers ◴[23 Aug 25 22:27 UTC] No.44999620[source]▶
It only works for trains because the image of train at t+1 is basically image of train at time t shifted over by a few pixels, right? It doesn't seem like this would work to capture a picture of a human, since humans don't just rigidly translate in space as they move.
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2. makeitdouble ◴[23 Aug 25 22:40 UTC] No.44999699[source]▶
If the human is running and doesn't frantically shake it decently works. There's samples of horse race finishing line pics in the article, and they look pretty good IMHO.

It falls apart when the subject is either static or moves it's limbs faster than the speed the whole subject moves (e.g. fist bumping while slowly walking past the camera would screw it)

3. flir ◴[23 Aug 25 22:45 UTC] No.44999717[source]▶
Depends what you're going for.

https://en.wikipedia.org/wiki/Slit-scan_photography#/media/F...