Capture plates between these two poles?

[Robert G.]

I currently have a Hikvision camera setup, but want to play with LPR.

It appears Dahau is the best choice for implementing a LPR solution.

I am currently considering adding Dahua HFW5241E-Z12E to my setup.

I currently have a PTZ camera up in the location where I am considering adding the new camera.

Took a photo, at 12mm from the install location (attached)

I think I should be able to install the new camera a aim it between the two poles, with the
sweet spot being maybe around 235 ft away from the camera.

At full zoom I would have a 4° viewing angle, which I plotted on the aerial view.

Anyone see any issues I should be concerned about or will this configuration work?

 

[Wildcat_1]

I have both a Dahua 5231-Z12 & 5241-Z12. I’m capturing plates in excess of 150ft (approx 165ft now) but that really is about the max you could go. The 5231 has a little more IR length than the 5241 so if you can plan to put your target the south side of say 145ft I.e where that white car is in your pic then you should be ok but will have to play on install. Key is height, angle and distance to target. It doesn’t look like you have options for a choke point so would be capturing at speeds similar to my situation 30+ mph. For clarity, any reason you don’t want to capture closer ? Don’t get me wrong you have a nice long run up to your areas you marked but even with a slight off angle you could still pull plates a little closer if you needed to. Just a thought.

Hope that helps. Be sure to check out other posts here by myself @bigredfish and others where we share tips on setup, dialing in the image etc.

 

[Parley]

In my experience I would go between the box and the first pole. I would cheat closer to the first pole. Maybe the left edge of the picture at the first pole. Again in my experience a little angle seems to be better at night in capturing plates with those two cameras.

 

[mech]

I agree with them ^ I would aim for the road by the 132ft pole or closer, unless there's a reason you have to go farther (for example, if there are often parked vehicles in one area but not the other). Don't stress too much about the slight increase in cross-angle if it buys you much larger plate images for the LPR to read. This is my LPR's viewing angle and it works just fine:

 

[Parley]

Let me add to my post above. You will need to see what is best for your situation and lighting. You may wind up with the camera aimed more to the box when it all said and done. Anyways my guess is somewhere between the box and the first pole. Mech's picture is a classic example of the "angle". When I am going frame by frame of my night video of a plate, the angle brings in a sharper image than a more head on shot.

 

[Robert G.]

Thanks for the input guys. As you can see in the photo I have a clear line of sight, no trees and there is generally never anyone parked on the road.

From further reading, I did after posting that, it seems keeping the distance at or below 100ft is best.

That photo from mech of the parks and recreation truck is amazing that the camera can pick that up.

I am going to see if I can calculate some rough angles from the aerial view.

Oh, does lighting make any difference? If I have a choice to snag photos at night under a street light or no street light is there much difference? The pole 132ft out is a street light.

 

[Robert G.]

OK, I calculated some rough angles.

Taking into consideration the angles, everyones comments and samples photos I think I can get away with aiming the camera somewhere between 120 - 150ft. That would put the camera angle to the road somewhere between 20 & 25 degrees. My original plan would have put the target area at 235ft (too far) with a 12 degree angle to the road.

I only get one shot at getting the setup right, as I only visit the site 1 time per year...

I'm attaching a night photo from the current camera (12mm) and indicating the target area where I hope to be able to get shots of the license plates. My guess is the street light would not help in this case as the IR is probably what is important.

 

[mech]

That photo from mech of the parks and recreation truck is amazing that the camera can pick that up.

If you think that one was amazing, check this example out (car from nearby sketchyhouse, I was researching who drives it). That's at 180 feet, from like 70 degrees off-axis. Our state's plates are relatively LPR-friendly, so that helps.

 

[Robert G.]

mech, that is crazy. If you can get LPR off angles like that I should have no problem with my 25 degree angle.

What software do you use to process the plates?

 

[mech]

I'm using OpenALPR (paid version in my case). From a front view, my plates are usually about 110-120 pixels wide with individual characters about 15 pixels tall. From a strictly LPR point of view, it would be better if I could zoom in more, and get bigger plates, instead of capturing a bunch of peripheral view, but 1) the lens is a fixed 50mm so I would have to aim the camera closer in or replace the lens, and 2) sometimes parked cars choke down the actual capture zone to half the normal size. It is what it is, I guess. I'm watching Ebay for a 75mm lens that fits this thing

I should also mention that the car above was at a complete standstill in excellent lighting conditions, or it would not have gotten captured. But I agree with you, your 25-degree angle should work if the shutter speed is high enough. You could add a super-high-output infrared emitter to take the shutter speed up further, like a CMVision IR-200. Relevant video demo:

 

[Robert G.]

I was thinking about adding an external light, as I actually have a very expensive light I bought that does not really perform well in it's current location. Take a look.

Light Off



Light On



The light is installed above the front step, it REALLY lights up the roof of the step but other than that I don't find it worthwhile to even run. It lights up the white house a bit but basically I'm not happy with it.

I thought I might be able to move it to the street side and use the light there, so I plotted the manufacturer specs to see what it might cover but no good for the license plate project. So I plotted another model from the same manufacturer and it would certainly cover the area but the lights are very expensive.

The model of light (that I don't have) gives 30 degrees coverage, out to 270 ft. So assume 1/2 of that and it should be able to nicely reach my target area.

 

[mech]

The key will be to get it as close to the camera as possible, so the reflection from the plates comes back at the camera. Here is my Black Oak IR pod, the super-spot featured last in the video, which is going under a Clinton enclosure for a buddy. These are about $100 if you want to go wild and get one (the IR pod, not the whole enchilada):

 

[Robert G.]

Yea, the IR light I bought was nearly 3x as much as that Black Oak. The light is POE so I did not have to hire an electrician to come and install power. I would cost several hundred just to have an electrician install the power, which is why I went for the POE light.

 

[mech]

That explains the expense. Well this does run on 12-volt power, so if you wanted to repurpose your Cat6/5 cable to carry 12v power, it would be a simple soldering project. Make two of the twisted pairs the ground, the other two the +12V line, and there you go. At the other end, slap on a decent-sized 12V power brick, my test was with a 7-amp brick. The key, however, will be for the IR to be right next to the camera, and it sounds like your present cable runs to a totally different location.

 

[Robert G.]

I can run the Cat5 cable no problem, have run thousands of feet of that stuff. I have a couple POE power splitters I bought off Amazon, to power an external microphone the next time I visit the site as well. I may investigate that as a means to power an external IR light.

Sorta sucks you have to get it that close to the camera, the reason I like the concept of the external IR is that bugs will not be flying around the camera. If I put the light a few feet away from the camera, the bugs can fly around the IR light all they want without it impacting anything.

 

[mech]

I think a cam that's dialed down to LPR'able settings (super-fast shutter, focus point way out in the distance, and pitch-dark picture except for the plates) will be basically immune to bugs in the IR beam.

 

[Robert G.]

Just wanted to post an amazing update about this.

At the BACK of the building we have a PTZ camera, with a big zoom - I think it goes to 94mm.

I was wondering if, maybe, the camera could zoom to the street. The target area it could potentially see would is the same as the target area that I would use for LPR. I would of course mount the LPR camera on the FRONT of the house resulting in it being closer and at better angle.

Here is the top view of where the PTZ is and the target @ about 150ft away.




My rough calculations put the angle from the camera to the street at 53 degrees.

Can this possibly work? Hell yea!!!!



I've set the PTZ to automatically adjust itself, change the exposure, capture rate etc. etc. when it is daylight. At night it goes back to its normal duties as there is no IR so that would be impossible.

I'm very impressed with the camera & the OpenALPR software. The pair, under these less than ideal conditions captured about 500 plates during the first 8 hours of operation. So I now know for sure that putting an LPR system on the FRONT of the house will be a totally viable solution.

 

[Laserray]

That's kind of amazing. That 53 degree angle would blow it for me. Nice shot! I can get 200 feet at about 25-30 degree angle with a 55mm camera, but not at that angle.
Are you using the commercial OpenALPr version?

 

[Robert G.]

@Laserray I am currently using the trial version of Open ALPR. It is not so clear on their website what features & functionality go away when the trial is over. I'm just waiting to see what happens to the software.

I know the free edition is supposed to support 2 cameras, and I have only one so that part should be OK.

What they are not clear about is other features, like will NVIDIA functionality still work??? That is the type of thing I am waiting to see.

 

[Laserray]

@Laserray I am currently using the trial version of Open ALPR. It is not so clear on their website what features & functionality go away when the trial is over. I'm just waiting to see what happens to the software.

I know the free edition is supposed to support 2 cameras, and I have only one so that part should be OK.

What they are not clear about is other features, like will NVIDIA functionality still work??? That is the type of thing I am waiting to see.

As far as I can tell, nothing changes all that much. They limit storage, and they limit the number of "hits".
Right now you re getting unlimited "hits". Every time data is sent to the API that's a "hit". If you let agent do the work of sending to API you are getting charged for 2-6 "hits". Some of those "hits" are junk.
Doesn't matter much now, but figure 1-2 cents a hit over a month.
I did post the PHP code to do this in this forum, if you are interested.

My solution was to stored all the plate data I could during the free two week onto a MySQL DB. Now I use the free version first to find the best image I want to send. If I don't have the plate on record, I send it to the commercial version. The free version is not as accurate and doesn't include vehicle data.
I do this to keep below the 1000 hit limit.