Ask HN: What are you working on? (February 2025)

I live next to a school, so there's a low speed limit (30 km/h). Still, people drive like race drivers and the city hasn't ever responded to the residents' hopes of introducing a speed camera.

I wanted to have some data on how many people speed, the max speed recorded, that sort of thing. Things the city should be doing after many complaints of dangerous driving and people being almost killed on zebra crossings.

I have a doorbell camera, and by analysing the footage using OpenCV and some code, I can track how fast people drive if you see how fast they move between two known points.

Average speed: 46 km/h :(

Is that legal in your country? In mine (Netherlands) there are way too many people with doorbell camera aimed right at the street even though it's illegal to record a public space like that. Most folks are ignorant about it though, or think that surely the internet-connected gadget sold by some anonymous corporation won't be abused....

For private use you can film in public places in the Netherlands no?

It is the "systemic/constant/permanent" recording, record-keeping. etc. a.k.a. "processing" (GDPR "processing" means "if it exists and you touch it, your are processing it").

Back in 2005 I remember working with some physical sec company that were setting up cameras in a factory, and they wanted the cameras to 'not record traffic, be activated on if THIS part of the screen has motion')(sidewalk vs sidewalk-right-on-our-doorbell vs road). Also, sudden changes in lighting would trigger it :)

Then you need to have retention period (good luck). Most people use those door-cams are violating GDPR. UNLESS when people complain and take you to court (very very very rare), you can prove that "I auto-delete records after 24h when there is no incident", "I have proximity scanner so it is only 0m-2m from my front door", etc.) (violating GDPR because "hey you pervert why do you record my kids EVERY DAY going in and out")

Privacy and Data protection is very very very difficult with GDPR (and thank you Facebook for messing up back in 2015ish!!!)

You can set up your cam but have the "AI" automatically pixelating all license-plates, and the video recording (if any) should be post-pixelating, and not the original feed. How about you put something with a speed-measuring-sensor (that is NOT a camera), so you only get 'anonymised' data, i.e. "20 moving items", and their speeds. But you will not be able to tell if the 300km/h was done by a bicycle or a Hayabusa ;)