[HN Gopher] Show HN: Build a DIY license plate reader with machi...
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Show HN: Build a DIY license plate reader with machine learning
Author : calebkaiser
Score : 116 points
Date : 2020-09-16 14:51 UTC (8 hours ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| dickfickling wrote:
| This is great! I've been meaning to build something like this for
| a long time. I'm always excited when I notice I've passed the
| same car on commutes on different days, or see a car I recognize
| from home in a different part of town. Automating that process
| and having my phone tell me e.g. "You just passed a car that you
| once drove past 1,000 miles away from here" is such a tempting
| side project. Bit big-brothery, though.
| ocdtrekkie wrote:
| Yeah, I am interested in adding LPR to my car's computer at
| some point, but it'd be locally processed and stored for
| personal reference.
|
| I'd maybe like to know if it detects the plates of people I
| know well nearby (sometimes I wonder when I see a car I feel I
| recognize), and I'd want to be able to mark bad drivers I see,
| and be warned if they come near my car again.
|
| My thought is that if I am driving around a driver bad enough
| that I think about the risk of accident, I might want to know
| if they're close to me again in the future.
| tgot wrote:
| I want this tied to a crude speed estimation algorithm, from a
| stationary camera.
|
| Even with ALPR retention restrictions, I could trigger a video
| save and send the police a video of the idiots doing 50mph
| through the residential neighborhood.
| ALittleLight wrote:
| For speed estimation, I wonder if the simplest thing would be
| two plate readers a fixed distance apart. Say they're
| attached to light poles N meters distant.
|
| When the reader triggers and takes a picture, it pings your
| server for a timestamp. It does the processing and records
| car X at time T provided by the timestamp. You then calculate
| the speed by the distance between the two meters divided by
| the time between the two timestamps for X.
|
| Provided that speeding cars are a problem in your
| neighborhood, I bet you could find the people responsible for
| the light poles (which likely have power associated to them)
| to let you install the devices, especially if you're
| providing the devices and servers.
|
| I don't think you'd necessarily be able to ticket the drivers
| though, as you're not law enforcement. Maybe you'd be able to
| work with local law enforcement though.
| groby_b wrote:
| "You, too, can now actively participate in the surveillance
| state"
|
| Yes, I get the technical appeal. I wish we all wondered less if
| we could, and more if we should.
| pc86 wrote:
| I'm much less concerned about this being used by a private
| citizen to keep license logs along with dash cams, integrate
| ALPR output into dash cam footage, etc, than I am about the
| surveillance _State_ as a whole.
| mitchtbaum wrote:
| https://music.youtube.com/watch?v=w1mUAVPaX98&feature=share
| giarc wrote:
| Am I missing something or in this image, is the confidence score
| 99.23% and has the incorrect license plate? The plates clearly
| have a 5 but it's predicting an S.
|
| https://camo.githubusercontent.com/5138d6bce5c840d15e533db6f...
| cochne wrote:
| Typical model output is not actually a probability, but a
| mostly arbitrary number between 0 and 1. Models usually have to
| be calibrated to match probability.
| cptskippy wrote:
| Is that confidence for the value or the category. It comes
| after LP in the image which makes me think it's the confidence
| that it is a license plate, not necessarily the confidence of
| the reading of said license plate.
| giarc wrote:
| You might be right. The gif on github, at times, shows no
| plate prediction but still includes a confidence score. I
| would suspect that if it can't even show a prediction, it's
| confidence score wouldn't show either (being that it would be
| 0%).
| cptskippy wrote:
| > I would suspect that if it can't even show a prediction,
| it's confidence score wouldn't show either (being that it
| would be 0%).
|
| Recognizing that something is a license place, and being
| able to read the plate are mutually exclusive things.
| People can identify license plates even if they can't read
| them, and people who don't know what a license plate is my
| still be able to read the numbers on them.
|
| The ML has to do two things; the first is reject anything
| that isn't a License Plate, the second is OCR License
| Plates.
| hundchenkatze wrote:
| Nope, you are correct. Wow, both examples from that image are
| wrong.
| IncRnd wrote:
| 99.23% is not 100%. 1/130ish But, the wrong examples don't seem
| a good demonstration of that...
| CleanItUpJanny wrote:
| sweet, time to add this to my car and make some dough selling
| license plate locations to Facebook Custom Audience
| techbio wrote:
| "Do-it-yourself" seems like a not quite appropriate title for an
| interface that calls a webservice with pre-built vision ML.
| parasanti wrote:
| I was thinking the same thing. If it was all localized to a Pi
| then yes, but outside services isn't really DIY so much. Maybe
| half DIY if such a thing.
| sokoloff wrote:
| On the other hand, I would tend to agree that this project is
| a "DIY Alexa" (edit to add: in the minds of most readers of
| Instructables website): https://www.instructables.com/id/DIY-
| Amazon-Alexa/
| hundchenkatze wrote:
| This is another example of what the GP comment is
| complaining about. It's not a DIY Alexa. Alexa is the
| virtual assistant API. This is a DIY Amazon Echo that still
| relies on the Alexa service.
| sokoloff wrote:
| As an engineer and a technologist, I agree that you and
| GP are precisely correct.
|
| If you showed it to and asked a string of randoms off the
| street, I think way more than half would agree with the
| "DIY Alexa" label as reasonably communicative description
| and more useful than a longer but more precise title.
| hundchenkatze wrote:
| Yeah, that's a good point. It's easy to get caught up in
| our little tech bubble :)
| varispeed wrote:
| This is CIY - cobble it yourself.
| alexchamberlain wrote:
| The actual computation here shouldn't be that great, right?
| (especially given the RPi has a GPU on) Seems like an
| inconsiderate design to stream images to a cloud service, rather
| than process locally and stream the plates themselves.
| calebkaiser wrote:
| Hey HN,
|
| I'm Caleb, and I'm a maintainer of Cortex, an open source model
| deployment platform. Not long ago, we published this DIY license
| plate reader project, and I wanted to share it here for anyone
| who is interested in computer vision or production machine
| learning in general.
|
| The project is a web service that accepts images and, using three
| trained models, returns extracted license plate text, assuming
| there is a license plate in the image. Of the models used, two
| are pre-trained models from keras-ocr, while one is a fine tuned
| YOLOv3. All models are freely available.
|
| You can see a video of the project in action here:
| https://www.youtube.com/watch?v=gsYEZtecXlA
|
| And read a write up by Robert Lucian, the maintainer who
| spearheaded this entire project, about how he built a camera
| system to interface with the web service using a Raspberry Pi and
| 5G: https://towardsdatascience.com/i-built-a-diy-license-
| plate-r...
| omgwtfbyobbq wrote:
| This looks very neat. Do you think something like a Jetson Nano
| would be able to handle inference locally?
| calebkaiser wrote:
| Thanks! The short answer is that I don't know, as it's only
| been run on EC2 instances, but given its current compute
| needs, probably not.
|
| The longer answer is that this project has a ton of room for
| optimization, some of which is mentioned in the repo, and
| with lower latency requirements + optimizations, I don't see
| why it wouldn't work on less powerful hardware (I've never
| personally worked with the Jetson Nano, so I don't want to
| speak with any false confidence on it specifically).
| jmnicolas wrote:
| I wonder if it would be more efficient with OpenCV?
| calebkaiser wrote:
| That's very possible. The Python interface for writing
| prediction APIs makes it pretty easy to switch between
| models, so it shouldn't be hard to test.
| yuvadam wrote:
| How does this implementation perform compared to classic
| approaches such as OpenALPR [1] ?
|
| At the very least running local inference becomes much more
| expensive, and possibly provides worse results.
|
| [1] - https://github.com/openalpr/openalpr
| tyingq wrote:
| I wonder how much more revenue police departments are making with
| ANPR[1].
|
| They can, for example, have a camera in all the cruisers, and
| automatically alert when a nearby car has an expired
| registration, inspection, etc. Or, if they have the tie-ins,
| registered to an owner with an open warrant or unpaid traffic
| citations.
|
| [1] https://en.wikipedia.org/wiki/Automatic_number-
| plate_recogni...
| tangled wrote:
| I've pondered the implications of running an 'installation art'
| project where a bunch of these are deployed around a city, with
| aggregated data visible over a web UI (assuming that this doesn't
| violate any laws.) The aim would be to raise public awareness of
| pervasive surveillance, and perhaps catalyze changes to the law.
| pc86 wrote:
| Regardless of the content, I think the idea of an installation
| art project whose goal is to make the art project itself
| illegal is pretty cool.
| [deleted]
| jlturner wrote:
| Take care to understand your local law regarding automatic
| license plate recognition. Use of such software and/or data
| collected with it may be under regulation. IANAL, but see your
| state statutes here if you live in the US:
| https://www.ncsl.org/research/telecommunications-and-informa...
| lubesGordi wrote:
| The site makes it sound like it's only illegal for law
| enforcement to do this.
| joncrane wrote:
| I find it interesting that some states are trying to regulate
| something like this.
|
| What if you had a child read off every license plate they see
| and use voice recognition to record the license plates?
|
| Is it illegal in real time, but allowed if you replay your
| dashcam footage later?
| arcticfox wrote:
| The vast majority of those laws seem to be targeted at law
| enforcement. I imagine any system designed to automatically
| collect license plates would be included, whether it's sync
| or async.
| varispeed wrote:
| What if you let the child buy drugs? Same thing. Don't let
| your child do illegal things and better - don't help it. If
| you hear your child is reciting the number plates, make sure
| all recording hardware in your car is off before you lecture
| the kid that what it does is absolutely forbidden.
| bobbean wrote:
| Good luck having someone do that 24 hours a day, or during
| rush hour. I assume it's more about bulk collection.
| jmnicolas wrote:
| The photos I saw seemed to be in Paris, and I'm pretty sure
| it's illegal to run a license plate reader in France.
| csours wrote:
| I've been watching dashcam footage lately and thinking about
| this. It would be very helpful for hit and runs if the dashcam
| had some on-board recognition that saved the last x license
| plates just like it saves the last x seconds of videos.
|
| Often the video footage is not good enough to get a plate because
| the capture settings are set lower so that more footage can be
| stored.
| master_yoda_1 wrote:
| can somebody tell this joker that it is illegal and stay the fcuk
| away from my car.
| hundchenkatze wrote:
| It _may_ be illegal where you live, but you have to remember
| that people live in other places than you, with different laws.
| cptskippy wrote:
| It's probably not illegal where they live judging by their
| tone. Often people who don't like something will tell you
| it's illegal to gain your compliance relying on your
| ignorance. They usually cuss and make a big show of it.
| darkport wrote:
| This is great. One of my side project ideas is to build an ANPR
| based app and 'social network' starting with basic tracking, I.e.
| you've passed this car 4 times before. I'm new to the ML world so
| still learning vut Do you think this is feasible to run in real
| time using CoreML on iOS?
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(page generated 2020-09-16 23:00 UTC)