Best PTZ with License Plate Recognition

joogle

Young grasshopper
Jul 11, 2022
44
5
Orlando, FL
Hi - I have a SD49225XA-HNR from Empire Tech but am thinking of upgrading it and need help identifying some options. This is for home use and would want something that as better picture quality, auto tracking and can read license plates both in day and night.

Now I just moved all my cameras away from Lorex to the Unifi Protect system. I was thinking of their PTZ but I think there are better quality PTZ from other providers potentially.

Would appreciate the inputs.

Thank you!
 
If you are going to use a PTZ to read plates, at night you have to turn it into essentially a fixed lens camera.

As an example the 49225 is a great autotracking PTZ, but at night, you won't be able to see and track cars and get plates, at least reliably.

You would have to set the camera up specifically to read plates. You need the proper camera with OPTICAL zoom for the distance you are covering and the angle to get plates.

Regarding plates, keep in mind that this is a camera dedicated to plates and not an overview camera also. It is as much an art as it is a science. You will need two cameras. For LPR we need to OPTICALLY zoom in tight to make the plate as large as possible. For most of us, all you see is the not much more than a vehicle in the entire frame. Now maybe in the right location during the day it might be able to see some other things, but not at night.

At night, we have to run a very fast shutter speed (1/2,000) and in B/W with IR and the image will be black. All you will see are head/tail lights and the plate. Some people can get away with color if they have enough street lights, but most of us cannot. Here is a representative sample of plates I get at night of vehicles traveling about 45MPH at 175 feet from my 2MP 5241-Z12E camera (that is all that is needed for plates):

1675078711764.png



See the LPR subforum for more details.
 
Thanks - so with the 49225 are there any settings you recommend to improve image quality - also one challenge im running into is saving changes - i have Firefox to access the camera functions but now to change the auto tracking from 15 seconds to 30 seconds, it won't save changes.

I completely get your point on another dedicated camera for LPR. Now - I have a street light right in front of the view. I guess I can run another cable to that corner and then supplement with an LPR camera. I know Unifi has one as well since almost all my cameras outside the 49225 is now on their Protect system.
 
Thanks - so with the 49225 are there any settings you recommend to improve image quality - also one challenge im running into is saving changes - i have Firefox to access the camera functions but now to change the auto tracking from 15 seconds to 30 seconds, it won't save changes.

I completely get your point on another dedicated camera for LPR. Now - I have a street light right in front of the view. I guess I can run another cable to that corner and then supplement with an LPR camera. I know Unifi has one as well since almost all my cameras outside the 49225 is now on their Protect system.

The Dahua PTZs, especially the 49225 won't hold settings in anything but Internet Explorer.


How to enable native Internet Explorer in Windows 10 and 11:
  • Open Notepad:
    • Copy then paste the single line of code below into Notepad:
    • CreateObject("InternetExplorer.Application").Visible=true
    • Save as OpenIE.vbs
  • Make sure the the file name ends in .vbs not .txt, If it ends in .txt you must rename to .vbs
  • Create a shortcut to the above file and double-click it anytime you want native Internet Explorer.

You don't need to run another cable. Many use this:

POE Splitter


In terms of getting the most out of the camera, here is my "standard" post that many use as a start for dialing in day and night that helps get the clean captures and help the camera recognize people and cars.

Start with:

H264
8192 bitrate
CBR
15FPS and iframes if using 3rd party VMS (30 if using NVR is ok)


Every field of view is different, but I have found you need contrast to usually be 6-8 higher than the brightness number at night.

We want the ability to freeze frame capture a clean image from the video at night, and that is only done with a shutter of 1/60 or faster. At night, default/auto may be on 1/12s shutter or worse to make the image bright.

In my opinion, shutter (exposure) and gain are the two most important parameters and then base the others off of it. Shutter is more important than FPS. It is the shutter speed that prevents motion blur, not FPS. 15 FPS is more than enough for surveillance cameras as we are not producing Hollywood movies. Match iframes to FPS. 15FPS is all that is usually needed.

Many people do not realize there is manual shutter that lets you adjust shutter and gain and a shutter priority that only lets you adjust shutter speed but not gain. The higher the gain, the bigger the noise and see-through ghosting start to appear because the noise is amplified. Most people select shutter priority and run a faster shutter than they should because it is likely being done at 100 gain, so it is actually defeating their purpose of a faster shutter.

Go into shutter settings and change to manual shutter and start with custom shutter as ms and change to 0-8.3ms and gain 0-50 (night) and 0-4ms exposure and 0-30 gain (day)for starters. Auto could have a shutter speed of 100ms or more with a gain at 100 and shutter priority could result in gain up at 100 which will contribute to significant ghosting and that blinding white you will get from the infrared or white light.

Now what you will notice immediately at night is that your image gets A LOT darker. That faster the shutter, the more light that is needed. But it is a balance. The nice bright night static image results in Casper blur and ghost during motion LOL. What do we want, a nice static image or a clean image when there is motion introduced to the scene?

In the daytime, if it is still too bright, then drop the 4ms down to 3ms then 2ms, etc. You have to play with it for your field of view.

Then at night, if it is too dark, then start adding ms to the time. Go to 10ms, 12ms, etc. until you find what you feel is acceptable as an image. Then have someone walk around and see if you can get a clean shot. Try not to go above 16.67ms (but certainly not above 30ms) as that tends to be the point where blur starts to occur. Conversely, if it is still bright, then drop down in time to get a faster shutter.

You can also adjust brightness and contrast to improve the image. But try not to go above 70 for anything and try to have contrast be at least 7-10 digits higher than brightness.

You can also add some gain to brighten the image - but the higher the gain, the more ghosting you get. Some cameras can go to 70 or so before it is an issue and some can't go over 50.

But adjusting those two settings will have the biggest impact. The next one is noise reduction. Want to keep that as low as possible. Depending on the amount of light you have, you might be able to get down to 40 or so at night (again camera dependent) and 20-30 during the day, but take it as low as you can before it gets too noisy. Again this one is a balance as well. Too smooth and no noise can result in soft images and contribute to blur.

Do not use backlight features until you have exhausted every other parameter setting. And if you do have to use backlight, take it down as low as possible.

After every setting adjustment, have someone walk around outside and see if you can freeze-frame to get a clean image. If not, keep changing until you do. Clean motion pictures are what we are after, not a clean static image.
 
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Also I know with LPR cameras it seems they need to be quite close to the street - anything that can capture it from a distance?

The image in my post above is from 175 feet - is that considered quite close?

1759888139919.png


In terms of Dahua cams, the following are used for LPR:

5442-ZE - if within 20ish feet

5442-Z4E if within 60ish feet

5241-Z12E - if withing 200ish feet

Beyond 200 feet is a PTZ that is basically turned into a fixed cam.