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Comment by _rnwu | Hacker News Reader

> Thirdly, this will create a lot of noise for law enforcement agencies which may mask other higher priority crimes.

If it becomes accepted as an automated solution where either a very quick human check or no human check is required, it would reduce their burden.

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> if it becomes accepted as an automated solution where either a very quick human check (e.g. that the wheel locations are indeed correctly identified) or no human check is required, it would reduce their burden

To put it politely, please take off the rose tinted spectacles.

Incase it had escaped your observation, a whole industry has sprung up where specialist lawyers make themselves available to challenge speeding tickets.

These speeding tickets are challenged on technicalities.

These technicalities relate to ?

That's right, issues with CALIBRATED fixed or mobile speed detection equipment, operated and maintained by trained individuals.

Typically the crux of the legal challenge is built around ?

Yes, that's right. Issues with the calibration of said equipment.

So, the chances of law enforcement issuing fines based upon "evidence" of speeding based on something that some random app on someone's phone has spat out ?

Yes, that's right. Zero, zilch, nada.

Unfortunately what that all REALLY means is that this system will only catch/charge speeders who also happen to not be able to afford a lawyer to challenge it or take the time off to take it to court.

Yes. To be fair all low value financial punishments are ethically reprehensible on this ground. They don’t dissuade anyone with money because the consequences are low or easy to appeal and people who are poor are punished harder. This ends up in a situation where punishment causes an even larger cultural divide or pushes people to other crime to make ends meet.

Some systems address this by scaling the fines to income. Finland comes to mind.

That doesn’t really work either. I can afford to lose 75% of my income in any month. I have been in a situation where losing 5% of my income is financially crippling.

Lot of assumptions here on measurements which really make this laughable. You need the following to make the measurement have any sort of validity:

Assuming simple s = d/t

1. The wheelbase data source is accurate. (d)

2. The vehicle type identification is accurate (d)

3. The centre of the wheels is identified correctly (d)

4. The wheels being on the same vehicle are identified correctly (d)

5. The measurement resolution is limited by pixel resolution so the image needs to be large enough to not lead to quantization errors (d + t)

6. The direction of travel of the vehicle is accurately determined (rate of motion is different if car moving away) (d)

7. The rotation of the vehicle is accurately measured (wheelbase compressed if turning away from the camera) (d)

8. The phone's camera is digitizing frames at the same rate without jitter (t)

9. The video source is actually coming from an actual camera and has not been modified by the user to incriminate them (d+t)

10. The camera isn't being moved in sympathy with the reference frame (d+t)

11. The reference frame is identified correctly (d+t)

12. the correct set of wheels on the vehicle are identified (d)

13. The shape of the lens of the camera (wide angle lens distortion) (d+t - possible calculus fun there)

I'd take the other arguments apart but I don't think I need to.

Edit: keep finding more problems with this.

Don't forget, a defendant has the right to subpoena the device that took the video/measurement. Users should be aware that they can essentially lose control of their phone during this process.

There's a reason most police departments forbid personal devices from being used to collect evidence in most circumstances.

And potentially a right to subpoena the source code to the software in some circumstances I believe.

(6) and (7) are not assumptions - the angle you are looking from doesn't make a difference, the time taken between each wheel crossing the same part of the image is the same.

What happens if the plate is incorrectly read? I have had this with my old vehicle leading to being fined for entering a car park but not leaving it.

I disagree with points 6 and 7 entirely. You can observe wheelbase compression standing on a tight bend with your eyes which are fairly low precision.

Also throw an extreme scenario on the table. If you're travelling at 70mph, that is 31m/s or 1m image resolution for a 30fps video. If your wheelbase is 3m that's a resolution of three frames to pass which is well below any threshold where a credible measurement is possible as you convert from discrete to continuous time.

Of course that brings in the problem that lower speed resolution is probably better so I should probably be driving around at 70mph in a 30mph in my 6x6 Land Rover 130 (sorry couldn't resist that).

I think there are too many assumptions to make a reliable measurement within a tolerance for the purpose described. The existing measurement devices have to be calibrated and must be operated within certain constraints to make an accurate measurement otherwise the information is inadmissible. Your app doesn't contain 1/10th of the assurance or competency that would be required. All it does is allow really annoying people to annoy people.

Have you joined any local community Facebook groups? Neighbours (vigilantes) posting about neighbours speeding/illegally parking their cars/noise issues or other mundane HOA violations doesn't deter anyone from these actions, if anything it creates a ton of fighting and drives communities apart.

You know what would also reduce their burden... Not getting speeding complaints from some random app.

How are you achieving the ANPR? I'd have thought that would add a fairly significant cost.

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