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Ask HN: Most interesting tech you built for just yourself?

1901 points l2silver | 1 comments | 27 Apr 23 15:04 UTC | HN request time: 0s | source

Maybe you've created your own AR program for wearables that shows the definition of a word when you highlight it IRL, or you've built a personal calendar app for your family to display on a monitor in the kitchen. Whatever it is, I'd love to hear it.
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jo-m ◴[28 Apr 23 08:49 UTC] No.35738987[source]▶
I have a rail line right under my apartment, so I built a small computer vision app running on a Rasperry Pi which records each train passing, and tries to stitch an image of it.

It has a frontend at https://trains.jo-m.ch/.

Edit: it's currently raining and the rain drops are disturbing the images a bit.

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dllu ◴[28 Apr 23 18:48 UTC] No.35745463[source]▶
Have you considered getting a line scan camera for sharper and higher resolution images? I took some train scans with one: https://daniel.lawrence.lu/photos/

Incidentally I also built some tech for it: https://github.com/dllu/nectar but I need to update the readme...

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mcast ◴[28 Apr 23 19:58 UTC] No.35746328[source]▶
Thanks for sharing, those photographs are very clear and sharp (especially this one: https://pics.dllu.net/file/dllu-pics/boston-pcc.jpg) it seems to tickle my brain.
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1. dllu ◴[28 Apr 23 23:21 UTC] No.35748386{3}[source]▶
I have three of those actually:

https://daniel.lawrence.lu/photos/pcc

Technically, the photo could be twice the resolution, since the length of the line scan sensor is 4096. It consists of two lines, RGRGRG and GBGBGB. By interpolating the red and blue channels, it would be possible to get images 4096 pixels tall. The challenge is that the two green channels apparently have quite different sensitivity and also each pixel has some variation in sensitivity, which also seems to drift with temperature and settings, so it's quite annoying to calibrate everything properly haha.