What $ for a camera to read plates at `50 ?

[Digiscan 0]

For a camera set up with a pretty good field of view (e.g. 3.6 mm lens), what sort of money needs to be laid down for the clarity needed to read a plate on a moving car (normal residential speeds) at 50-60'?

 

I don't think this is simply a resolution matter, as a good 1 MP image can easily beat a bad 2 MP image, thanks to lens and image processing differences.

 

I assume at least a grand to reliably do this if not two, and maybe more, and I assume further that doing this also at night requires yet more money.

[bike_rider 0]

At some point, you can't argue with resolution. A quick run through a lens calculator says that a 3.6mm lens, with a 1/3" sensor, shows HFOV of 67' at a distance of 50'. US plates need at least 50 pixels per foot in good light. More in poor light. Taking 50 PPF, and 66 feet, that's an image with 3300 pixels across. You will need to adjust your scenario.

[ak357 0]

At some point, you can't argue with resolution. A quick run through a lens calculator says that a 3.6mm lens, with a 1/3" sensor, shows HFOV of 67' at a distance of 50'. US plates need at least 50 pixels per foot in good light. More in poor light. Taking 50 PPF, and 66 feet, that's an image with 3300 pixels across. You will need to adjust your scenario.

I am more conservative

75 pix minimum per foot even day time

[bike_rider 0]

At some point, you can't argue with resolution. A quick run through a lens calculator says that a 3.6mm lens, with a 1/3" sensor, shows HFOV of 67' at a distance of 50'. US plates need at least 50 pixels per foot in good light. More in poor light. Taking 50 PPF, and 66 feet, that's an image with 3300 pixels across. You will need to adjust your scenario.

I am more conservative

75 pix minimum per foot even day time

 

I do like your number better. I think I'm about 60-65 on my setup and night shots can still be dicey.

[Digiscan 0]

At some point, you can't argue with resolution. A quick run through a lens calculator says that a 3.6mm lens, with a 1/3" sensor, shows HFOV of 67' at a distance of 50'. US plates need at least 50 pixels per foot in good light. More in poor light. Taking 50 PPF, and 66 feet, that's an image with 3300 pixels across. You will need to adjust your scenario.

I am more conservative

75 pix minimum per foot even day time

So it sounds like we're looking at 15-20 megapixel images! That can't be cheap.

 

I guess a good way to test this would be to take one with my 16 MP camera and see what it looks like, though its field of view is quite tight.

[buellwinkle 0]

With LPR, having a lot of megapixels will work against you as OCR software may not be able to keep up. You need a very focused telephoto lens in the area where the plate will pass through, not the scenery or the entire car. You can have a separate general purpose camera for the shot of the car. The camera should be very high contrast, B&W camera for this purpose. For high speed capture with the OCR built in, you may be looking at $2-3K from what I've seen.

[ak357 0]

With LPR, having a lot of megapixels will work against you as OCR software may not be able to keep up. You need a very focused telephoto lens in the area where the plate will pass through, not the scenery or the entire car. You can have a separate general purpose camera for the shot of the car. The camera should be very high contrast, B&W camera for this purpose. For high speed capture with the OCR built in, you may be looking at $2-3K from what I've seen.

 

OP was not talking about OCR at all

He simply want to capture best possible shot of Lic plate

Shall I type slow for you ?

[buellwinkle 0]

Yes, if you can because what's the point of LPR if the camera or software doesn't convert the license plate to text so it can be compared to a list. Or does he just want a camera where you can ID the license plate as that's different for me. Just a good WDR camera will work. The biggest problem is at night with cameras that have built in illuminators where it reflects of the reflective license plate and all you see is a white rectangle.

 

BTW, the OP said "READ PLATES". To me that's not taking a picture of a plate, but actually read the plate. I'm actually looking for an ALPR camera that can "READ PLATES" and feed it into an access control system to log plates. Reading involves comprehension, otherwise you would look at plates, not read them.

[ak357 0]

Yes, if you can because what's the point of LPR if the camera or software doesn't convert the license plate to text so it can be compared to a list. Or does he just want a camera where you can ID the license plate as that's different for me. Just a good WDR camera will work. The biggest problem is at night with cameras that have built in illuminators where it reflects of the reflective license plate and all you see is a white rectangle.

 

BTW, the OP said "READ PLATES". To me that's not taking a picture of a plate, but actually read the plate. I'm actually looking for an ALPR camera that can "READ PLATES" and feed it into an access control system to log plates. Reading involves comprehension, otherwise you would look at plates, not read them.

 

Well u can be easily prove wrong

I can show u plate completely white under IR ( as u call white rectangle)

but when u zoom in u can easily read plate

Of course how it's done is BIG secret

[buellwinkle 0]

It's a given that in order to see a plate number, you would have to have adequate focal length to fill the frame as much as possible with a plate. I've tried two cameras, one without WDR, the ACTi TCM-7811, can't see plate numbers at night, the KCM-5611 with WDR (or ExDR as they call it) can see plate numbers so camera choice is important just to be able to see a plate at night.

 

But the question still exists to the OP, does he want the camera see plate numbers or read plate numbers?

[Digiscan 0]

It's a given that in order to see a plate number, you would have to have adequate focal length to fill the frame as much as possible with a plate. I've tried two cameras, one without WDR, the ACTi TCM-7811, can't see plate numbers at night, the KCM-5611 with WDR (or ExDR as they call it) can see plate numbers so camera choice is important just to be able to see a plate at night.

 

But the question still exists to the OP, does he want the camera see plate numbers or read plate numbers?

In point of fact I'd not thought of the difference when I posted, so I appreciate both views on this

[MaxIcon 0]

Well u can be easily prove wrong

I can show u plate completely white under IR ( as u call white rectangle)

but when u zoom in u can easily read plate

Of course how it's done is BIG secret

 

Do you mean when you zoom in with the camera, or when you zoom in on the recorded video?

[ak357 0]

Well u can be easily prove wrong

I can show u plate completely white under IR ( as u call white rectangle)

but when u zoom in u can easily read plate

Of course how it's done is BIG secret

 

Do you mean when you zoom in with the camera, or when you zoom in on the recorded video?

Good question

yes, on recorded video

 

1.zoom in

 

2.without zoom in

[thewireguys 3]

Nice images... I need to watermark them next time

Edited August 21, 2012 by Guest

[buellwinkle 0]

In point of fact I'd not thought of the difference when I posted, so I appreciate both views on this

 

There are LPR specific cameras that are high contrast camera, many times just B&W sensors and have very good low light capabiliy and faster shutter speed at night for high speed license plate capture. To get a proper one, one that can see a plate clearly at 50-60 mph is not cheap. You would typically have software on a PC that's OCR software for license plate recognition that analyzes the image, converts it to text and matches it up to a list and then acts on that list. The software may send an alert, may be able to trigger a gate to open.

 

Lately a new class of LPR cameras have evolved called ALPR. These have the processing capabilities in the camera to read the plate and process the information as an event, much in the same way you have motion events. The event can trigger an alarm output say to trigger a parking garage or street gate to open if the license plate matches a list of residents or sending out an email or text if a unauthorized car entered, maybe by tailgating.

 

At ISC West earlier this year, one vendor demo'ed an ALPR camera that outputted text license plate numbers at amazing speed. He put like 8 plates on a drum and spun it as fast as he could and the camera captured every single plate number. I believe they rated the camera to capable of capturing a license plate at 190 mph.

 

But that may be overkill if all you want to do is record video of cars going by and have enough qualiy to be able to see the plate number in the image. If that's the case, look for cameras that have very good WDR capabilities and very good low light capabilities and really good contrast.