Turning a Train into a Flatbed Scanner
Using the railway network as a flatbed scanner
A photographer builds a DIY scanning camera using an industrial line-scan sensor and mounts it on trains and ferries to capture ultra-wide, high-resolution images. The project involves overcoming challenges with speed measurement, exposure, and post-processing, resulting in stunning panoramic shots of Boston and San Francisco.
I was watching a video on Gigawipf's medium format scanning camera build and suddenly thought: 'what if the entire camera moved and the subject didn't?'
- msisk6
Ward Cunningham and I did something similar back in 2008.
We were both at a startup in Portland and our office was along the railroad tracks east of the Willamette. We were up on the 4th or 5th floor right above a lot of train traffic including Amtrak.
I brought in some extra Mac gear I had including one of the early iSight cameras which back then was an external device you stuck on the top of your display and connected to the Mac via FireWire. We set it up and rolled the desk over to the window in the office and turned the camera around pointing down at the tracks and Ward got to work hacking something up to do a slit scan.
It was a fun little project; the speed of the trains affected the horizontal compression of the images. We could tweak the software to expand or contract the size of the image by adjusting the number of slit scans per unit of time. Of course, that affected the exposure but I recall the camera having some automatic adjustments that gave us trouble.
That's about all we did with it. Just a quick afternoon hacking project. Neither of us thought much about it at the time so we didn't save anything.
- decae
I've posted this here before but I have been creating animations using a similar process with a regular camera and manually splicing the frames together. [1,2,3] The effect is quite interesting in how it forces focus on the subject reducing the background into an abstract pattern. Each 'line' is around 15px wide. I think I went through exactly the same thought process as the author, funny how ideas can come up independently like this.
[1] https://youtube.com/shorts/VQuI1wW8hAw [2] https://youtube.com/shorts/vE6kLolf57w [3] https://youtube.com/shorts/QxvFyasQYAY
I also shot a timelapse of the Tokyo skyline at sunset and applied a similar process [4], then motion tracked it so that time is traveling across the frame from left to right[5]. Each line here is 4 pixels wide and the original animation is in 8k.
[4] https://youtu.be/wTma28gwSk0 [5] https://youtu.be/v5HLX5wFEGk
- jonty
If you want to play around with slit scanning, I made this little toy a number of years ago and frequently find myself using it on trains:
Press and hold your phone screen to switch between the front/back cameras, or hit "c" on a computer. Tapping the screen saves the image, as does "s".
- Terr_
Recycling comment from another submission 17 day ago:
> Random thought: If you stick a very small adhesive mirror to the outside window before boarding, then footage "looking down" at the regularly-spaced railroad ties could contribute to information about the current speed and acceleration.
> Well, on a straight section anyway, if you turn, the inner/outer edges will appear differently-spaced...
> Wouldn't do anything positive in terms of suspicious staff though. They might think it's like some kind of heist-movie that will involve a specialized glass cutter making a circle on the window.
- mhb