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Using the railway network as a flatbed scanner

philo.gay

31–40 of 81 posts

Re: Using the railway network as a flatbed scanner

#34

Great writeup! Planned doing the same thing Herr in germany. Thought a Smartphone camera would be enough but there no way to access the camera2 api for those highspeed recordings. I took 1h long 240hz 4k vertikal videos (out of the Schwebebahn in Wuppertal) which could be displayed by MacOS preview. Right no im waiting for a good gaussian splatting tool to create the driving of the "Train” in Blender. The newest Ling…

Ohhh, nice; happy to have a chat on the subject; suggest a messaging option to discuss further if you're interested. Check out keybase on my profile for some listed contact options; you can also use the padlock symbol in the menubar there to PGP encrypt a message to me and share that through any suitable channel that can handle that ascii.

Edit: I've captured and extracted-to-textured-mesh Mirker Bahnhof before it got covered by the scaffolding; if you're going to do another recording I'd highly recommend you include an IMU recording and ideally (though much less critically) a GNSS raw measurements recording that includes carrier phase. I've got a recorder for the latter that exposes a simple USB-serial port that should work great unless the GTW15 windows are EMI-shielding (but iirc they aren't).

Re: Using the railway network as a flatbed scanner

#36

Reminds me of when railways attempted to attach linear barcodes on their train and read it using a similar method

KarTrak!

It was one of the first large-scale commercial applications of barcodes, and at one point 95% of railroad cars were equipped with it. Could've been a success, but it was a few decades too soo, and a handful of small but crucial implementation flaws doomed it to abandonment only a decade later.

Re: Using the railway network as a flatbed scanner

#37
Taken to the extreme....

I gotta wonder. Owen from RanOutOnARail could make some incredible wide pictures from his journeys if he had this setup. Been watching his YouTube channel for years [0], [1]. He has a Patreon account with more videos [2].

He use to have a lot more videos on YouTube. It's illegal to ride trains the way he does, but his videos helped get me through the long time of the covid pandemic after I would stop work for the day.

[0] https://youtube.com/@ranoutonarail?si=ElAeMpcrJASsE3Ov

[1] https://youtube.com/@rooar2?si=bx1AG5kp2r4rfzcq

[2] https://www.patreon.com/u40099464

Re: Using the railway network as a flatbed scanner

#38
> but I think the results speak for themselves.

... as in not very good compared to normal camera ? Acceleratometer-based correction can only do so much

Normal camera allows you to get a snapshot of 2D area instead of 1D area so you can make any correction for movement afterwards. With linear one you just get artifacts like the introductionary pic being very wobbly up and down.

Re: Using the railway network as a flatbed scanner

#39
post #16

Lynx photo finish cameras. Same idea: https://www.finishlynx.com/

Line scan cameras are (were?) also very common in industrial applications. It is the best way to take images of objects on a rapidly-moving conveyor belt as you don't have to be worried about blurring due to long shutter times, and you can achieve incredible frame rates.

The downside is that they are highly specialized (in other words: expensive) and require knowledge of the belt speed to reconstruct a proper image. I would not be too surprised if modern high-framerate video cameras took over a decent chunk of that niche.

Re: Using the railway network as a flatbed scanner

#40
post #7

Earlier quoted context omitted.

Do you think you'd be able to find this post (assuming it's still up)? Would love to see it.

https://www.sentex.net/~mwandel/tech/scanner.html

Oh, Matthias Wandel, of course. This would have been back when he was writing software for Blackberry instead of his current semi-retired woodworking YouTubing
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