LPR and overview camera

L

Lieberkind

Getting the hang of it
Dec 16, 2021
89
26
Denmark
Hi,

I have a Dahua cameras. mp2 for LPR recognition and 8mp for overview of my driveway.

My problem is that I would like to get plates both ways, entering exting the house. I have set the overview camera with ÍVS ( i have tried motion detection from BI) and triggering the LPR camera with camera group.

When I drive my own car up and down the driveway, I get decent images from LPR camera most of the times, but when i drive for work in the morning, the camera doesn't get an image. When other cars are driving to and from the house, somtimes the camera gets an images, sometimes not.

I am thinking what is the best way to trigger a LPR camera both ways?

I have tried zones from the overview camera without better results. My problem is that when cars are approching the camera, it should trigger immediately, but when driving away from the camera, it shoul trigger when tha back plate is in the FOV.

Hope somone can help. :)
 
IVS does not work well with LPR because the camera needs time to identify they object and determine if it meets the criteria. With how much most of us zoom in, it does not see enough of a car to reliably work. And then at night when all most of us see are head/tail lights and the plate, the camera can not identify that as a vehicle.

So you would have to run simple motion detection for the camera in this scenario, but even then that can be tricky, so you need to run Blue Iris motion detection instead of camera IVS.

I found this to be the setup that worked best for me. This one zone approach at this location allowed me to catch the front plate of the cars going right to left and the back plate of the cars going left to right. Occasionally I would get a large truck or a very fast vehicle that was missed, but I also run this continuous motion in the event that happens or it missed the motion. And then at night I simply make the object size box a lot smaller like the size of the plate. As you can see from the alert clips to the left that it captures all the cars in the middle of the frame. My nighttime is the same as well. If you are running a 1/2000 shutter then it should take out a lot of the headlight bounce that would come from the street that can cause it to trigger early.

If you are only interested in the back plate, then make another zone that is to the left of this and tell it to only trigger for motion from the zones going left to right.

1632795852923.png



Post your settings for day and night and the zones you have and we can help you out.

But it does take some trial and error to get this down.
 
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wittaj said:
IVS does not work well with LPR because the camera needs time to identify they object and determine if it meets the criteria. With how much most of us zoom in, it does not see enough of a car to reliably work. And then at night when all most of us see are head/tail lights and the plate, the camera can not identify that as a vehicle.

So you would have to run simple motion detection for the camera in this scenario, but even then that can be tricky, so you need to run Blue Iris motion detection instead of camera IVS.

I found this to be the setup that worked best for me. This one zone approach at this location allowed me to catch the front plate of the cars going right to left and the back plate of the cars going left to right. Occasionally I would get a large truck or a very fast vehicle that was missed, but I also run this continuous motion in the event that happens or it missed the motion. And then at night I simply make the object size box a lot smaller like the size of the plate. As you can see from the alert clips to the left that it captures all the cars in the middle of the frame. My nighttime is the same as well. If you are running a 1/2000 shutter then it should take out a lot of the headlight bounce that would come from the street that can cause it to trigger early.

If you are only interested in the back plate, then make another zone that is to the left of this and tell it to only trigger for motion from the zones going left to right.

1632795852923.png



Post your settings for day and night and the zones you have and we can help you out.

But it does take some trial and error to get this down.
Click to expand...

Currently i don't have zones, only IVS. I will try to create zones as in your image. should I use zones from overview camera or LPR camera?

Do you only have 1 zone? and how do you have the settings for that zone?
 
That is my zone for my LPR camera.

I have two profiles in BI - a day and night profile.

During the day, the motion detection target size is a lot larger so that only vehicles trigger it.

At night, the target size is the size of a plate, so pretty small. Since my image is completely dark except for when a vehicle passes, I do not get false triggers.

I have the make time set at 0.1 seconds.

I know some have been successful using an overview camera and zones to trigger their LPR camera, but I would try mine first as it takes another camera out of the equation.
 
wittaj said:
That is my zone for my LPR camera.

I have two profiles in BI - a day and night profile.

During the day, the motion detection target size is a lot larger so that only vehicles trigger it.

At night, the target size is the size of a plate, so pretty small. Since my image is completely dark except for when a vehicle passes, I do not get false triggers.

I have the make time set at 0.1 seconds.

I know some have been successful using an overview camera and zones to trigger their LPR camera, but I would try mine first as it takes another camera out of the equation.
Click to expand...

This is what i just made...

Day:
1643701547509.png
1643701584465.png

Night:
1643701642440.png

And same zone.
 
I do not have B&W and High Definition checked. That can sometimes be problematic for LPR and the tight field of view we have.

What FPS are you running at? I found that if I went above 15 FPS, BI would miss the motion. Because of the zoomed in field of view, it needs a bigger difference between the sensing blocks.

What do you have down for object detection - is it just the zone? Make sure the move so many pixels and reset after x% is unchecked.
 
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wittaj said:
I do not have B&W and High Definition checked. That can sometimes be problematic for LPR and the tight field of view we have.

What FPS are you running at? I found that if I went above 15 FPS, BI would miss the motion. Because of the zoomed in field of view, it needs a bigger difference between the sensing blocks.

What do you have down for object detection - is it just the zone? Make sure the move so many pixels and reset after x% is unchecked.
Click to expand...

my LPR cam runs at 10 fps. and I am only using zone B in object detection.
 
Sounds good - this should do it for you (fingers crossed)!

If it is missing, then simply add another "layer" of yellow motion detection blocks on your zone. Just keep making it slightly bigger until it catches them.
 
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wittaj said:
Sounds good - this should do it for you (fingers crossed)!

If it is missing, then simply add another "layer" of yellow motion detection blocks on your zone. Just keep making it slightly bigger until it catches them.
Click to expand...

Thank you for your help
 
wittaj said:
Sometimes not much you can do about that, especially wet pavement. You could lower the gain and increase the shutter speed and see if that makes it darker to knock a lot of it out.
Click to expand...

I got this image, but it gets cancelled. can you explain how that is? trigger is ok and the plate i visible. i don't understand why it gets cancelled.

But i get more accurate images now. :-)

1643783566079.png
 
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