←back to thread

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.
Show context
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.

replies(47): >>35739052 #>>35739094 #>>35739098 #>>35739186 #>>35739211 #>>35739212 #>>35739221 #>>35739399 #>>35739464 #>>35739755 #>>35739756 #>>35739856 #>>35739890 #>>35740154 #>>35740372 #>>35740582 #>>35740596 #>>35740795 #>>35741028 #>>35741183 #>>35741583 #>>35741681 #>>35741761 #>>35741910 #>>35741953 #>>35741980 #>>35742282 #>>35742809 #>>35743209 #>>35743361 #>>35743573 #>>35743806 #>>35744731 #>>35744938 #>>35745018 #>>35745415 #>>35745424 #>>35745463 #>>35746416 #>>35747604 #>>35749090 #>>35750218 #>>35751252 #>>35751495 #>>35761959 #>>35765014 #>>35785999 #
Jleagle ◴[28 Apr 23 09:30 UTC] No.35739211[source]▶
Sounds interesting id love to know how you do it. Is the speed calculated based on the noise of the wheels going over a track join? Then you can work out the length/speed based on the time it takes etc. Are the train types/images random or calculated some how?
replies(1): >>35739550 #
1. jo-m ◴[28 Apr 23 10:32 UTC] No.35739550[source]▶
There is a parameter which tells the program how many pixels there are per meter. From this you can compute the length after stitching. Using framerate, you can compute the speed in the same way.