Dedicated License Plate Cam project

[bigbadw]

i switch to black and white long before this.. the lpr camera is switching to B&W at least half an hour before sunset and holds onto it the same ammount after sunrise.

Wow, didn't even know that was an option... I'll play with that one for dawn tomorrow!

 

[bigbadw]

i switch to black and white long before this.. the lpr camera is switching to B&W at least half an hour before sunset and holds onto it the same ammount after sunrise.

nayr, I have come to the conclusion that my problem is the camera itself.

I am unable to capture a quality, readable picture during Dusk or Dawn each day. I've tuned the image, changed day/night start and stop times, overlaping dusk/dawn to try and get that readable image, all to no avail. (placing camera in night-mode is how I attain black/white imaging. I can't find any other option for to do that).

Again, the camera I am using is a Hikvision DS-2CD2T32-I8.

 

[bigbadw]

I am thinking of getting this camera and add an "external camera housing". Any comments or recommendations? Hikvision DS-2CD6026FHWD-A11

Note: I've included a PDF with the specs on the camera for your review.

 

[cam235]

@nayr : I have a "SavvyPixel" (Dahua) IPC-HF5421E which I think is the same as you're using for ALPR. Do you know if I can connect to this via RTSP and if so what's the string for it? I've got my other no-name and Hikvision cameras running with a NVR, but not the Dahua. I have found other rtsp strings online for various Dahua cameras, but not this specific model.

 

[nayr]

same as all other dahuas
rtsp://host:554/cam/realmonitor?channel=1&subtype=0

 

[cam235]

Sure enough that works, thanks!

Edit: I started another thread about longer lenses for ALPR, eg. 100 mm. I'm trying to get 300 feet and I actually can read them by eye, but the lenses I have are not quite enough for ALPR. ALPR: anyone have a 100mm lens they like?

 

[cam235]

I recently found out from Matt (author of OpenALPR) that it has trouble with plate frames that touch or partly cover the bottom of the letters on the plate. Google Groups
He said there is an experimental software feature to address the problem, but apparently it is not available in the free version. Problem is, here in California, this affects a large fraction of all the plates I've seen. Just curious: has anyone had success with OpenALPR in California?

 

[cam235]

With the 4500mW "IR Cannon" recommended by nayr I'm getting good images... except when this kind of thing comes along. Coating worn off from too much hand detailing at the car wash, I assume, but you have to wonder if people don't do it intentionally.

 

[bigbadw]

With the 4500mW "IR Cannon" recommended by nayr I'm getting good images... except when this kind of thing comes along. Coating worn off from too much hand detailing at the car wash, I assume, but you have to wonder if people don't do it intentionally.
View attachment 12725

cam235, I have been finding some interesting license plates as well. While most are bright and easily legible, a few have been unreadable and really interesting:
1. some simply are not reflective and cannot be read.
2. one car had the entire nose of the vehicle sprayed with a super reflective coating. It glowed like a light source as it drove by, obscuring the license plate area completely. This only happened once. I have been waiting for that vehicle to return.
3. bent old plates, again not reflective.
4. A dark, non reflective cover over the plates, and again, just cannot make out the numbers.

 

[cam235]

Yes, there are retroreflective spray paints, and plate covers sold for the express purpose of blocking traffic cameras. Search for "license plate blocker" to see examples

 

[bigbadw]

Damn!! That is an interesting segment of the population all right!
My newest experiment in night time license plate capture is to use an "super-low light" camera. It should be here by next week. I am interested to find out if it can capture better detail at night.
Hikvision DS-2CD6026FHWD-A3
Some of the specs claim: Color: 0.002 lux @ (f/1.2, AGC On) and B/W: 0.0002 lux @ (f/1.2, AGC On)

Should be interesting!

 

[blake]

So what box camera would you guys recommend for LPR duty?

 

[cam235]

I got the same 4MP Dahua box camera nayr has for ALPR (see his signature) and it's fine so far as it goes, but in my particular situation I was unable to get a long enough lens (100mm or so) to work at 300 feet which is what I need. So today I took delivery of a Sunba 20x PTZ, and it does the job for about the same money as the Dahua box cam + lens + illuminator BUT I have to make a kludgy tilted mount because the silly thing cannot view the horizon, it can only tilt about 5 or 10 degrees below horizontal. To get a true horizontal view you have to get the next model up, which is larger and $100 more, and I'm cheap. The PTZ action may not be as good as Dahua, but it's for one view angle only and I don't intend to move it. The software+firmware maybe isn't as good as Dahua but the RTSP stream works, and that's all I need.

 

[blake]

Did you purchase the normal Sunba or the poe combo version?

 

[cam235]

@blake I got the non-POE version from that Amazon link, it comes with a 12V 2A adaptor. I may have spoken too soon- during the day it worked fine. At night, the image is too bright (gain up full) so all plates are completely washed out. There are several exposure settings in the MSIE browser plugin that worked during the day, but they have no effect in night mode (!?)

Below are three images from the Sunba 507-20XB (2 MP white 20x PTZ), all at max zoom (f= 94mm). The camera looks towards a T intersection which is 330 feet away, the yellow house beyond is at 450 feet. First image during the day, second at night without a car, third with a car driving away. Clearly, not too useful at night, unless I can adjust the gain down somehow. Also the full-time autofocus tries to resolve the big fuzzy taillights / headlights and makes things worse.



Having a quick scan through the 507-20XB thread here (I should have done before buying!) I have a sinking feeling that the camera is simply unsuitable for LPR use. It looks like the gain can not be adjusted down.

 

[bigbadw]

cam235, that is a beautiful daytime shot!

 

[blake]

Than you for the images. Outside of LPR use, how does the camera perform for normal duties?

 

[cam235]

If I didn't want LPR, I'd probably keep the camera. The 20x zoom is decent and it's less expensive than similar alternatives. Apart from fixed gain-up at nighttime, the other annoyance is it will not look directly horizontal; only about 5 or 10 degrees short of it, and if you try to cheat and tilt the mount up to see the horizon, the image isn't straight up and down if you then pan around. The pan action is fairly slow, it doesn't whip around. Check out the 507 thread for more info: Sunba HZ507-20XB Mini Dome PTZ Camera

UPDATE: Sunba Tech Support actually replied to my email with a google drive link to firmware they said should improve night overexpoure. The bad part: their link was 404 - Not Found :-/
EDIT2: Got the new firmware, installed, still can't control image brightness and now RTSP is broken as well! Tech support super-quick, but couldn't fix it. Fortunately I bought through Amazon... it's going back. Kind of sad about night performance, since during the day the camera does well (below example at max zoom)

 

[Bradmph]

I used the following settings to get a good exposure on the Huisun 10X for license plate viewing at about 100ft. to 125ft. IR on.
I only cropped the images to remove dead unused area to reduce size of file only.
Images taken between 12:30am and 1:30am in very low lighted area of the street. Residential.
Test images with an extra license plate placed in the position your focusing on.

1. PTZ to the location desired.
2. Set the Image / Exposure settings to Shutter Priority, Shutter 1/1000, Exposure Bias On: Comp Level 50, Cain Limit 50
3. Image / Focus to Manual, Min Focus Distance to INFINITE
4. Manual focus the camera to the the general distance of where license plates will be.

 

[blake]

Sorry the Sunba didn't work out.