Dashcams and license plate recognition

Quartz · 3 Aug 2020 at 00:06

Is license plate recognition something that could be built into dashcams? Is it particularly computationally intensive? Picking out a plate number after the video has gone through lossy compression is often problematic, so if it were done beforehand, it would be most useful.

I'm not asking for full ANPR like the police have but just something that will recognise and decode the numberplates on the cars on screen, perhaps listing them at the top of the video, so we don't have to struggle.

Rroff · 3 Aug 2020 at 00:13

You can get phone apps which will do it - though I doubt they have the features to do it and overlay in real time. For something like a dashcam you'd probably need a dedicated chip which can accelerate the process so unlikely to be a feature outside of specialist hardware.

EDIT: Apparently G9WB based dashcams have some kind of feature like that and I found a few threads from a quick google on DIY setups.

BUDFORCE · 3 Aug 2020 at 07:42

Haze · 3 Aug 2020 at 07:46

BUDFORCE said:
Why?

This ^^^

And buy a better dash cam so you can see the plates...

How many accidents are involved in every year, for this to be an important feature??

jsmoke · 3 Aug 2020 at 08:20

I'd imagine it would take a fair bit of power, the police generally sit at the side of the road and hence have a limited area to monitor.

[TW]Fox · 3 Aug 2020 at 08:25

Quartz said:
Picking out a plate number after the video has gone through lossy compression is often problematic

Why are you picking out other people's numberplates from video frequently enough for this to be 'often problematic' for you?

Yaayuh! · 3 Aug 2020 at 08:33

Haze said:
This ^^^

And buy a better dash cam so you can see the plates...

How many accidents are involved in every year, for this to be an important feature??

This ^^^

InvaderGIR · 3 Aug 2020 at 08:42

As most have said, why? But also, it's not so much lossy compression as rubbish cameras which might well have FULL 10K SUPER DOOPER ULTRA HD descriptions but actually, the chips and lenses used are awful and whilst you have your desired output image size it's awful quality due to rubbish hardware.

Resident · 3 Aug 2020 at 08:49

jsmoke said:
I'd imagine it would take a fair bit of power, the police generally sit at the side of the road and hence have a limited area to monitor.

Traffic units have constant AnPR monitoring whilst driving.

jsmoke · 3 Aug 2020 at 08:50

Resident said:
Traffic units have constant AnPR monitoring whilst driving.

Any idea what equipment they use?

InvaderGIR · 3 Aug 2020 at 08:51

Resident said:
Traffic units have constant AnPR monitoring whilst driving.

This is true, but they have better cameras and actual computers to do the processing.

sigma · 3 Aug 2020 at 09:08

Surely a dash cam that has a poor quality output meaning that number plates aren’t readable makes it a pointless cam? If someone hits you and drives off the cam needs to be able to show the reg surely? I’d imagine it’s quite tough to view plates at night or in low light conditions.

jsmoke · 3 Aug 2020 at 09:16

sigma said:
Surely a dash cam that has a poor quality output meaning that number plates aren’t readable makes it a pointless cam? If someone hits you and drives off the cam needs to be able to show the reg surely? I’d imagine it’s quite tough to view plates at night or in low light conditions.

You can get the plate from stills, maybe between about 10 frames you can get the plate if not close too.

tom_e · 3 Aug 2020 at 09:43

sigma said:
Surely a dash cam that has a poor quality output meaning that number plates aren’t readable makes it a pointless cam? If someone hits you and drives off the cam needs to be able to show the reg surely? I’d imagine it’s quite tough to view plates at night or in low light conditions.

They're not just useful for someone who hits you and drives off but also for evidence in a who was at fault discussion.

Quartz · 3 Aug 2020 at 11:04

BUDFORCE said:
Why?

Why not?

[TW]Fox said:
Why are you picking out other people's numberplates from video frequently enough for this to be 'often problematic' for you?

I've just been watching some dashcam videos.

sigma · 3 Aug 2020 at 11:20

You may not have many accidents but if you do then surely you want their reg to be clearly visible.

Howard · 3 Aug 2020 at 11:32

The frame rate of the video has a big impact on this. With the usual fair-to-middling quality dashcam image sensor, you're much more likely to see the plate of a moving car at 60FPS vs 30, for example.

[TW]Fox · 3 Aug 2020 at 11:56

Quartz said:
Why not?

Why not leave automatic recognition of private citizens numberplates to the police? Why do you want to be able to record so much information about total strangers?

Quartz · 3 Aug 2020 at 11:59

[TW]Fox said:
Why not leave automatic recognition of private citizens numberplates to the police? Why do you want to be able to record so much information about total strangers?

Because the quality of the compressed video is so poor. If ANPR is done by the camera itself it will be operating on the higher-quality uncompressed video.

InvaderGIR · 3 Aug 2020 at 12:15

Quartz said:
Because the quality of the compressed video is so poor. If ANPR is done by the camera itself it will be operating on the higher-quality uncompressed video.

It's not the video compression, it's the camera itself as already stated.

The only compression "issues" are when people upload their inane clips (usually the camera driver is in the wrong anyway) to YouTube and the likes.