Dedicated License Plate Cam project

[Kawboy12R]

I have one of those with the 12 millimeter lens on order for plate duty as well. If 12 doesn't cut it then I have an extra 25 to throw in to boost things up a little bit. I ordered it quite a while ago too. Stuff I ordered a lot later than that has arrived a while ago. When they said airmail for this one they must have meant by balloon.

 

[nayr]

mine's watching street parking right now but the angle is so good on that intersection.. the 12mm can just barely read plates @ 4MP, and not good enough for OpenALPR.. since its a big bullet I am hoping it has the room inside for larger optics.

If all works out I'll have 2 dedicated license plate cameras, and get one of the new 2MP StarLight Varifocal Turrets from dahua to watch the street parking that this camera is doing currently.

 

[cam235]

I ordered a M12 25mm lens from http://www.ebay.com/itm/282167088666 a few weeks ago but I do not recommend them if you're in a hurry- it took 10 days before it even shipped out of China, and it's still on its way so I have yet to evaluate it. I think my existing 16mm is not enough; the plate images are legible to the eye but even in good light the alpr readout is wrong as often as it is right. If I take a clear image of a plate using my cellphone, then alpr is usually always right.

If you want to print out a plate (just for daylight testing) check out https://acme.com/licensemaker/

@pozzello : I'm scripting alpr on Linux, it's an Acer C720 that I converted to Ubuntu 14.04. The C720 is discontinued but I think the C740 is similar. I have not had good luck running windows boxes 24/7 long-term.

 

[nayr]

I ordered this one from the US: http://www.ebay.com/itm/281503028725

Its got a bigger aperture, F1.4 vs F2.4 and is avilable from the US.. but it is of course its 4x the cost heh.

 

[cam235]

> Its got a bigger aperture, F1.4 vs F2.4 and is avilable from the US.. but it is of course its 4x the cost heh.

I have one of those lenses, at least it looks exactly the same including the printing. Hopefully it will work for you, I'll be curious to hear about it. I found the image very soft and fuzzy on my copy. Any spec from China vendors is suspect, but I've found an actual difference between a lens marked simply "MP" and a "5 MP" lens.

 

[Kawboy12R]

Just for giggles I double checked my shipping times. It took 8 days from order until AliExpress said that it had shipped. Then it was two weeks until epacket said it had left China. That was over 2 weeks ago, so over 5 weeks and counting. Some things I have ordered came in 10 to 14 days total even without DHL.

 

[bigbadw]

Ok, I have daytime license plate capture (LPC) working.. I now have nightime LPC working (MANY thanks nayr and pozzello!!)

I am now trying to figure out how to get legible license plates during dusk and dawn. I experimented with nighttime settings of Brightness, Contrast and Sharpness. I will see if these new settings will still allow full nighttime image captures tonight.

Did you folks need to modify anything to work during those time frames (dusk and dawn)?

Note: I have a second IR Illuminator on order to set up a nightime capture for the opposite direction (both coming and going of traffic). I already have daytime cameras set up in both directions. It is amazing how many times a car has only one set of license plates (on front or back) and a few times how one of the plates is actually illegible from the camera angle.

Another experiment I am trying is to install a second hard drive, so that the two cameras do not run into a bottle neck while trying to write the captured images to the hard drive.

 

[cam235]

I would expect the same light and camera config that works at night should work as well at dusk and dawn. The only problem would be if your camera switches to "day" mode (changing shutter speed and putting in the IR-cut filter) too soon. In that case you could put some medium-dark filter over the light sensor so it sees only full daylight as "day" (and same for the sensor on the IR light, if it has one) or command the changeover remotely from another computer at the right time. For example, I have a Raspberry Pi running the PiKrellCam software. This allows script actions to fire at X minutes before or after sunset and sunrise each day. It maintains accurate sunset/sunrise times across the seasons because it calculates them based on your Lat/Lon coordinates.

 

[bigbadw]

Thank you for the response cam235. I can manually schedule the day/Night settings and will experiment with those to see the results! Thanks again.

 

[nayr]

without real 120dB WDR I would really struggle at dusk/dawn too.. it allows me to read plates at those times alot easier than without it.

 

[bigbadw]

without real 120dB WDR I would really struggle at dusk/dawn too.. it allows me to read plates at those times alot easier than without it.

Damn.. I may have the wrong camera then... I have a Hikvision DS-2CD2T32-I8. It only has Digital WDR.
I am going to experiment with turning it on and adjusting it between 1 - 100 (Wide Dynamic Level). No idea what that will do though.

 

[pozzello]

i don't have any problems reading plates at dusk or dawn. I do have BI changing presets ~30 min after dawn/dusk to correct the 'focus float' that seems to happen with plates.
for some reason, plates in the dark (with IR illumination) require a slightly closer focus than the same view during the day. Seems the retro-reflective aspect makes them appear closer at night by a couple focus clicks. but other than that focus issue, i don't change anything else for day/night.

 

[nayr]

think it'll kinda depend on the environment.. my birdhouse camera is on an east/west road looking east.. so in morning plates are in deep shade, and in the evening they are in a bunch of shadows from the trees but at certain times they might be in direct sunlight as it peeks through.

this next lpr camera Im planning is on a north/south road with it looking north; the lighting conditions will be much better and it might not need WDR at all with plates having a southernly view.

I have the same focus issue; reflective objects flared up by IR are further away than they appear.. im not sure how well a fixed lens setup will do, gona give it a try but I expect the focus to be a big compromise.

leme try to dig up some sample captures

 

[cam235]

I do not see a dynamic range problem at dusk and dawn (which I understand to mean the sun is not in the sky). I do have that problem in mid to late afternoon where a plate might be in direct sun but the background is not.

 

[j4co]

If all works out I'll have 2 dedicated license plate cameras, and get one of the new 2MP StarLight Varifocal Turrets from dahua to watch the street parking that this camera is doing currently.

this seems to be a video of one:
looks quite good in the dark.

 

[bigbadw]

I set played with adjustments on the WDR (digital not true WDR), last night. Turning it on, and adjusting to the lowest of settings (8), very readable License plates are captured all night, as well as dusk and dawn. (I set the start time and stop times to compensate for dusk and dawn manually).

nayr, I noticed that the IR Illuminator is adjustable from 5-90 degrees. No instructions came and I have not located them on line. Unfortunately my installation is about 15 feet up a large tree in the front yard, so experimenting with different adjustments can be done, but it makes it more difficult. By any chance, do you know what the adjustments are? I believe the way to adjust the beam is on top of the light, and possibly turning the "screw" clockwise or counter clockwise. Is this correct? Which adjustment makes it a tighter beam vs broader beam? (turned all the way down, or clockwise makes it a smaller beam?)
Appreciate your help on this.

 

[nayr]

you pull out on that knob it and twist it one way to zoom in and the other way to zoom out.. then push it back in to lock it in place.

the direction? I forget.. when adjusting IR I usually put the exposure back to auto so I can see normal objects at night then go outside with a display (phone/tablet) and adjust it while watching the live feed... then when I have it where I want it covering the area i need then I go back and put the exposure settings back for plates.

Without a live display, look at the angle which you can see the IR out the front.. crank it all the way one direction and look into the end so you see the red glow (presuming you have 850nm), if you can see the lights still from an offset angle then its on wide.. if the lights go out as soon as you get off center then its on its most narrow angle.

 

[pozzello]

if you're illuminating plates at 60ft or beyond, you'll want/need to be at the narrowest setting, so you've really only got 2 things to test at either end of the adjustment range...

 

[car_wash_guy]

This thread has been a great read. I just ordered a Huisin v2 for my LPC cam for one of my business locations. I look forward to sharing my experiences.

 

[cam235]

with focused 850nm lights at night, if I hold my hand in front of the lens I can dimly see the projected light pattern. Definitely more awkward if you need the hand to hold onto the tree though. I had a camera creatively positioned in a tree for awhile but abandoned that location due to higher maintenance (my homebrew construction wasn't entirely waterproof and the view was affected by spiders, squirrels etc.)