OpenALPR Advice?

[DLONG2]

I signed up for the OpenALPR 'Cloud Stream' service, and it works really well with my highly-zoomed Dahua HFW5231EZ5 camera. It's not clear that this service will be a part of the advertised 'free 2 days of storage' plan. Also, I noticed the CPU usage has more than doubled just to allow the streaming service to scan for readable plates all the time. It is really convenient, though.

Any advice on the best use of this company's services? Their website isn't super clear on what the best fit would be for a hobbyist.

Funny to report that the streaming service tagged a neighbor's Lexus SUV's plate correctly, but called it a 'blue Lexus motorcycle.'

 

[wtimothyholman]

License plate recognition will continue to work once your trial period is over and you transition into the free plan. The main differences are that plates will only be retained for 2 days, and you won't be to set alerts (e.g. to send you an email if a specific plate is detected).

What I do is log in every two days and download the plate listing into a spreadsheet. No doubt it would be possible to write a script to automatically scrape the download page every 48 hours, but I haven't had time to look into it. Someone else may be doing it on this site.

For residential use, I'm satisfied with the free plan. The extra storage and alert features aren't worth the extra cost for my home, but if I was monitoring a business or school I would certainly consider paying for it.

The higher CPU usage is to be expected. The OpenALPR client has to preprocess the image data before sending it to the cloud. As for vehicle identification, that tends to be hit and miss, as you've already noticed. But as long as the license plate is recorded, the police can figure out the rest.

 

[actran]

@DLONG2 Have you tried running OpenALPR locally instead of using the cloud service?

The OpenALPR is open source and available on Github:
openalpr/openalpr

There is an older thread where people are running OpenALPR locally: LPR Walk Through / Tutorial

If you run it locally, there are no limits to data retention, plus, you are not sending data to an external cloud service.
Never ever trust any cloud service if you care about your privacy.
It is possible that any cloud service will misuse your data by accident (poor internal processes/management) or intentionally, and without your knowledge.

Example: Ring reportedly gave employees access to customer video feeds

 

[wtimothyholman]

No, I have not tried to run the sotware locally, just the client app. More Linux-capable people than myself have succeeded. Again, it's not a high priority with me for home use. If I needed the features of the paid service, I would certainly look into it.

 

[actran]

No, I have not tried to run the sotware locally, just the client app. More Linux-capable people than myself have succeeded. Again, it's not a high priority with me for home use. If I needed the features of the paid service, I would certainly look into it.

The convenience of cloud service is very compelling and easier to get up and running.
But now the cloud service will be able to figure out which license plates belongs to you and your family. They're probably the ones that consistently shows up the most often.
They will also be able to infer who your friends are by looking at those license plates and cross checking with other public/semi-public datasets.
Hey, just look at all the license plates that show up on Super Bowl Sunday.

They will know your schedule. When you leave/arrive at the house. Let's see what can be done with that data.... near real-time, meaningful, actionable data

 

[wtimothyholman]

The convenience of cloud service is very compelling and easier to get up and running.
But now the cloud service will be able to figure out which license plates belongs to you and your family. They're probably the ones that consistently shows up the most often.
They will also be able to infer who your friends are by looking at those license plates and cross checking with other public/semi-public datasets.
Hey, just look at all the license plates that show up on Super Bowl Sunday.

They will know your schedule. When you leave/arrive at the house. Let's see what can be done with that data.... near real-time, meaningful, actionable data

Everything you say is true. If someone were to gain access to that data, quite a bit could be inferred about me, given sufficient analysis.

But in the grand scheme of things that threaten my privacy, having my license plate records hacked at OpenALPR.com is so far down the threat ladder as to hardly be worth mentioning. I carry a smartphone in my pocket that can be used to track my location history, and everyone I have communicated with. I carry credit cards that provide a very detailed record of where I travel and what I buy. My insurance company has a complete online record of my health treatment and medications. In short, I have an online presence that is far too extensive for me to rein in without withdrawing from society entirely.

I do what any reasonable person can. I encrypt data and emails. I use firmware passwords on my computers. I have permanent freezes on my credit reports. I use unique passwords for every web site I visit. I enable two-factor authentication whenever it is available. I have reasonably strong protection against criminal attack. But if the bad guys really want to invade my privacy, they have far more efficient tools available than a record of license plates for automobiles that have driven by my house.

 

[DLONG2]

Thanks for all the input. Am glad to hear the free service will allow for streaming and 2 days of storage.

I've been busy today building an Azure database table, and parsing the dashboard website's HTML, and have some VB.NET application running which helps automate the CSV file download and importation process. Getting the images to download so that they can be uploaded into Azure is a bit of a bottleneck now, and I am doubting the usefulness of having an archived images of the vehicles, based on how much time it takes to get past the web server's 401 permission-denied errors.

 

[wtimothyholman]

Thanks for all the input. Am glad to hear the free service will allow for streaming and 2 days of storage.

I've been busy today building an Azure database table, and parsing the dashboard website's HTML, and have some VB.NET application running which helps automate the CSV file download and importation process. Getting the images to download so that they can be uploaded into Azure is a bit of a bottleneck now, and I am doubting the usefulness of having an archived images of the vehicles, based on how much time it takes to get past the web server's 401 permission-denied errors.

There's no need to grab the image of the vehicle or the plate. Those images do not reside in the OpenALPR cloud, they reside on the computer that is running the OpenALPR client. When you click on a plate number on the web page, the page is actually querying the agent on your computer to display the image.

 

[DLONG2]

There's no need to grab the image of the vehicle or the plate. Those images do not reside in the OpenALPR cloud, they reside on the computer that is running the OpenALPR client. When you click on a plate number on the web page, the page is actually querying the agent on your computer to display the image.

Interesting. Where do I find the images?

Aha. On the c:\openALPR\plateimages\1234567890.mdb

Alas, a fresh disappointment: MS Access doesn't recognize the database format.

 

[NetHunter]

wtimothyholman mind sharing the way you save the two days / script

 

[DLONG2]

The Dashboard / Details widget has a link at the bottom of the details listing for downloading the records in a CSV format.

 

[DLONG2]

Anyone have any leads on connecting with and getting the stored images from this local database? I am using the Cloud Stream service, running their local agent software on the BI PC.

c:\openALPR\plateimages\[1234567890].mdb

 

[wtimothyholman]

Anyone have any leads on connecting with and getting the stored images from this local database? I am using the Cloud Stream service, running their local agent software on the BI PC.

c:\openALPR\plateimages\1234567890.mdb

You can query the vehicle images directly from the OpenALPR client machine, using the following http query from another local device.

http://<client ip>:8355/img/<best-uuid>.jpg

The <best-uuid> field can be found in the .csv file that you can download directly from cloud.openalpr.com. Every image capture generates a unique <best-uuid> string.

So a typical query would be: http://10.0.1.27:8355/img/F7IVVVUWS6YHDY6ZDBRMDFP8NESX88KNY2F1XFLQ-1939245631-1537029071456.jpg, where the local client IP is 10.0.1.27, and the best-uuid string is F7IVVVUWS6YHDY6ZDBRMDFP8NESX88KNY2F1XFLQ-1939245631-1537029071456. Obviously the client IP will vary depending on your own network.

Note that you must open port 8355 on the client machine for this to work, so you'll need to configure the client's firewall if one is running. The only image that is saved is the vehicle image. From what I can tell, when cloud.openalpr.com shows a license plate image, it is cropping it from the vehicle image.

 

[DLONG2]

Thanks for the info, wtimothy. Using a chrome browser on the BI PC, the connection is refused, even with the firewall disabled. "The site can't be reached. Refused to connect".

 

[wtimothyholman]

Thanks for the info, wtimothy. Using a chrome browser on the BI PC, the connection is refused, even with the firewall disabled. "The site can't be reached. Refused to connect".

You also have to turn on the client web server. There’s a parameter called “web_server_enabled” in the client advanced configuration file that must be turned on. It is off by default.

 

[DLONG2]

You also have to turn on the client web server. There’s a parameter called “web_server_enabled” in the client advanced configuration file that must be turned on. It is off by default.

Thanks! That did it! Next I have to ask if the images will stay accessible in the local database after the 14 day free trial?

 

[wtimothyholman]

Thanks! That did it! Next I have to ask if the images will stay accessible in the local database after the 14 day free trial?

Yes. In fact, the images will remain accessible for as long as there is disk space available in the partition that you set up when you configured the client. I've pulled up images from weeks earlier, long after the plate numbers vanished from the cloud.

So even for the paid versions of OpenALPR, the 30- or 60-day storage limits are really artificial. The only items being stored in the cloud are the license plate numbers with the associated links to the files stored on your client. Your client machine is really doing all of the heavy lifting, so to speak.

The possibility exists for some motivated person to write software to scrape the OpenALPR cloud on a periodic basis, and generate an interface that would allow you to search for any license plate for as long as the image remains accessible on your client. So in theory one could maintain the data for months or even years. It's not something that I personally have the time or inclination to tackle, but someone else might.

 

[DLONG2]

Today I've completed the process of viewing the LPR data and images in a local Windows .NET form, via a hobby Azure database which I pay maybe $8 a month for. The application requests the CSV download, saves it, opens and parses it for new records, and adds them into the table. It will also convert the OpenALPR's universal time fields to local time strings so that the camera images' timestamp watermarks match the database time records. For the front end, there are various combo boxes for narrowing down a query, such as by distinct dates, colors, makes, models, etc.

I'm only 8 days into the 14 day trial, so I am unsure how often I'll need to download the CSV exports, because so far it pulls all records. Also, I'm still trying to fathom how the manual download link's URL is named, as the dates and times don't seem to match the earliest and latest records within the export.

 

[wtimothyholman]

Today I've completed the process of viewing the LPR data and images in a local Windows .NET form, via a hobby Azure database which I pay maybe $8 a month for. The application requests the CSV download, saves it, opens and parses it for new records, and adds them into the table. It will also convert the OpenALPR's universal time fields to local time strings so that the camera images' timestamp watermarks match the database time records. For the front end, there are various combo boxes for narrowing down a query, such as by distinct dates, colors, makes, models, etc.

I'm only 8 days into the 14 day trial, so I am unsure how often I'll need to download the CSV exports, because so far it pulls all records. Also, I'm still trying to fathom how the manual download link's URL is named, as the dates and times don't seem to match the earliest and latest records within the export.

Very interesting! I hope this is something you'll be willing to share once it's complete.

As for downloading, you need to download at least once every 48 hours to avoid losing records once you move to the free plan. One daily download will provide ample margin, provided you eliminate redundant records in your database.

 

[DLONG2]

Sure, I'll be happy to share the basic code for importing the data into a database, but I only have experience with MS Azure SQL. As long as the table fields and field types are defined then I am sure my code can be altered for a different storage.




The download button on the web page's Details page is interesting, as it utilizes local times in the GUI, but assures the CSV download will contain the universal time equivalents. Hence, a user on the Pacific coast might request a full day's download of 2019-02-01 00:00 to 2019-02-01 23:59 within the web GUI, and the CSV data will return 2019-02-01 08:00 to 2019-02-02 07:59, or an 8 hour offset. A button on a Windows form will work the same way as a browser's button; nothing in the web's 'download CSV' link indicates an agent client or account ID within the URL, so I am guessing the returned data is allowed because of cookies. At any rate, the correct images for the selected dates and times do get downloaded.



The goal is to get the downloaded CSV into the larger ListBox, for easy parsing and importing into the database. If anyone is interested in developing their own database for this project, please drop me a note.