Using PTZ Verifocal Camera as LPR

[pmcross]

Hi all,

I know that this is a stretch but I’m curious to see if anyone else has been able to use a PTZ with a verifocal lens as a LPR for vehicles traveling both directions instead of using two cameras. What I’m thinking is that this could be achieved by having two presets, one for cars traveling each direction and have a motion trigger using BI. The road that I’m looking to put a LPR has a stop sign at each end, which I should be able to achieve a decent view of with a PTZ. Just looking to see if anyone else has been able to get this to work with a PTZ.

 

[SouthernYankee]

I think the cars are to fast and the camera is to slow. Read all the problems people have setting up an LPR cameras.

 

[pmcross]

Thanks for the info. Fortunately my road is less than 1/4 mile and most cars go less than 15-20 MPH. Do you think that the cars would still be going too fast?

 

[wtimothyholman]

Hi all,

I know that this is a stretch but I’m curious to see if anyone else has been able to use a PTZ with a verifocal lens as a LPR for vehicles traveling both directions instead of using two cameras. What I’m thinking is that this could be achieved by having two presets, one for cars traveling each direction and have a motion trigger using BI. The road that I’m looking to put a LPR has a stop sign at each end, which I should be able to achieve a decent view of with a PTZ. Just looking to see if anyone else has been able to get this to work with a PTZ.

I use a Dahua SD49225T-HN camera for LPR during the day, as visitors sometimes park their cars on my street in such a way as to block one of my IPC-HFW5231E-Z12 varifocal LPR cameras during the daytime. At night it switches modes so that it records my front walk and my own car.

I haven't tried it for nighttime LPR operation, but I've seen nothing to indicate that it wouldn't work.

 

[pmcross]

I use a Dahua SD49225T-HN camera for LPR during the day, as visitors sometimes park their cars on my street in such a way as to block one of my IPC-HFW5231E-Z12 varifocal LPR cameras during the daytime. At night it switches modes so that it records my front walk and my own car.

I haven't tried it for nighttime LPR operation, but I've seen nothing to indicate that it wouldn't work.

Awesome, thanks for letting me know. Have you tried having the SD49225T-HN follow a car based on the direction of travel? I’m trying to eliminate the need for two LPR cameras.

 

[tangent]

Hi all,

I know that this is a stretch but I’m curious to see if anyone else has been able to use a PTZ with a verifocal lens as a LPR for vehicles traveling both directions instead of using two cameras. What I’m thinking is that this could be achieved by having two presets, one for cars traveling each direction and have a motion trigger using BI. The road that I’m looking to put a LPR has a stop sign at each end, which I should be able to achieve a decent view of with a PTZ. Just looking to see if anyone else has been able to get this to work with a PTZ.

I think you'd have a hard time getting to camera to the preset you want and focused reliably before a car passes. I don't see moving the camera back and forth to try to capture both directions of travel working well.

 

[wtimothyholman]

Awesome, thanks for letting me know. Have you tried having the SD49225T-HN follow a car based on the direction of travel? I’m trying to eliminate the need for two LPR cameras.

My apologies; I didn't ready your original post carefully enough, but now I see what you're trying to do. The SD42995T-HN doesn't have the auto-tracking feature, but other models do.

Regardless, I doubt it would work, at least not well, and certainly not at night. No matter how clever you try to be making one camera do the work of two, eventually you'll have a situation where two cars are coming from different directions, and one camera won't be able to cover both of them. Also, by every indication auto-tracking tends to be flaky, at least for Dahua cameras that are inexpensive enough to fall into the prosumer category. I wouldn't depend on it being reliable enough to accomplish what you want.

Dahua IPC-HFW5231E-Z12 or even SD49225T-HN cameras are cheap enough for you to afford to cover multiple directions.

 

[pmcross]

My apologies; I didn't ready your original post carefully enough, but now I see what you're trying to do. The SD42995T-HN doesn't have the auto-tracking feature, but other models do.

Regardless, I doubt it would work, at least not well, and certainly not at night. No matter how clever you try to be making one camera do the work of two, eventually you'll have a situation where two cars are coming from different directions, and one camera won't be able to cover both of them. Also, by every indication auto-tracking tends to be flaky, at least for Dahua cameras that are inexpensive enough to fall into the prosumer category. I wouldn't depend on it being reliable enough to accomplish what you want.

Dahua IPC-HFW5231E-Z12 or even SD49225T-HN cameras are cheap enough for you to afford to cover multiple directions.

No worries, I appreciate the info. I will likely just buy two cameras, one for each direction. I had a feeling that it probably wouldn’t work well, just trying to minimize my camera footprint since I already have a camera covering my driveway, so I would have 3 cameras to cover the front driveway/road

 

[wtimothyholman]

No worries, I appreciate the info. I will likely just buy two cameras, one for each direction. I had a feeling that it probably wouldn’t work well, just trying to minimize my camera footprint since I already have a camera covering my driveway, so I would have 3 cameras to cover the front driveway/road

My own advice: consider buying two PTZ cameras with a form factor similar to the SD49225T-HN, instead of fixed-direction varifocal cameras. Although the PTZ cameras are larger, the spherical inverted dome shapes tend to look like decorative lights at first glance, and are thus less noticeable.

 

[bp2008]

In my experience Dahua PTZ often have trouble autofocusing quickly at night so I wouldn't recommend having the LPR camera move automatically.

 

[pmcross]

Thanks everyone for the advice, I greatly appreciate it. I am going to do some testing with a varifocal camera that I currently use to cover my back driveway to see how it performs as a LPR before purchasing two PTZ or a bullet camera for LPR. I have also been looking at the Dahua turret cameras with varifocal lens for LPR too. Has anyone had a good experience with these?

Amcrest UltraHD 4MP POE Bullet IP Security Camera, 2688x1520, 197ft NightVision, MicroSD Storage, Motorized Varifocal Lens 55°-104°, 5X Optical Zoom, White (IP4M-1054EW) https://www.amazon.com/dp/B077BDWJ3D/ref=cm_sw_r_cp_api_i_XfqrCb57781XQ

 

[pmcross]

Hi @pmcross, that Amcrest camera looks like it’s very similar to a Dahua IPC-HFW4431R-ZS bullet (hacked Chinese camera). Probably an Omnivision 1/3” sensor and roughly the same lens. If it’s not too far to the target, you should be able to have *some* success with it.

I used one for a while for LPR with the target being about 65-70 feet. Daytime was no problem, but night was more difficult. In the daytime I could read 100% of the plates, nighttime around 80%.

(I’m not using any automated LPR software, I just manually go back through motion triggers and use my eyes to read them.)

For starting shutter speeds you can try 1/2000th daytime and 1/500th night.

You mentioned cars go pretty slowly on your road, which is good. You might be able to use 1/250th if there isn’t too much motion blur.

Thanks so much, @TheDank that sounds very promising.I will test out the shutter speeds that you mentioned. My target is about 50 to 60 feet too, so hopefully I’ll have success. I’ll post my results after the weather breaks here since I need to move the camera.

Take a look at OpenALPR. I signed up for an account and will be using the free edition for LPR
OpenALPR - Automatic License Plate Recognition

 

[aristobrat]

Thanks for the info. Fortunately my road is less than 1/4 mile and most cars go less than 15-20 MPH. Do you think that the cars would still be going too fast?

x2 on @bp2008’s comment. The zoom on my varifocals is pretty quick. The camera refocusing after a zoom is not always quick. I’m guessing you have to zoom in somewhat close to get the plates, which means the image isn’t very wide. My varifocals can take 2-5 seconds to refocus after a zoom. I don’t imagine a plate would still be in the cameras image at that point, but I am curious to see how it works for you!

 

[pmcross]

x2 on @bp2008’s comment. The zoom on my varifocals is pretty quick. The camera refocusing after a zoom is not always quick. I’m guessing you have to zoom in somewhat close to get the plates, which means the image isn’t very wide. My varifocals can take 2-5 seconds to refocus after a zoom. I don’t imagine a plate would still be in the cameras image at that point, but I am curious to see how it works for you!

This is good info to know. I’m inclined to agree with you regarding how long it takes to zoom and refocus for a PTZ. I’m going to do some testing with a 4MP Amcrest varifocal camera that I currently have.