Can I use a spotter cam to trigger an LPR cam to analyze plate data?

[prsmith777]

I've been trying for weeks to get one of my LPR cams at the front driveway to trigger correctly and ignore the busy street in the background. Im beginning to think its going to be impossible based on the cam position. The cam is in the ground in a cement pole with a fake rock so please don't suggest moving the cam.






Here is what Im up against.




No matter how I draw the IVS tripwire, intrusion or both, I either get no trigger or I trigger all the cars on the adjacent busy road.

Here are some examples






Any line that goes above the street line, whether intrusion of tripwire will trigger with street traffic.



Here is how it looks with a car driving up




Basically all of the car is in the field of the road.

So I could just have about 500 triggers per day and let it go, but I thought about another option. I have an overview camera that does not have false triggers from the road. Here is what it looks like





This last pic and the one with the car on the other cam are at about the same time.

If I could somehow use this cam to trigger the other LPR cam to start its data analysis, then problem would be solved. Not sure how to approach this though

Any help appreciated.

 

[wittaj]

First you need to make the rules larger above the vehicles as IVS is designed to trigger when half the object crosses the lines and best case you are only getting bottom quarter or so of car.

Second IVS won't work at night unless you have stadium quality lighting.

Best to use BI motion detection. And if that doesn't work, then yes you can use another cam to trigger for LPR, but that will also take trial and error cause it could be a couple second delay.

 

[prsmith777]

First you need to make the rules larger above the vehicles as IVS is designed to trigger when half the object crosses the lines and best case you are only getting bottom quarter or so of car.

Second IVS won't work at night unless you have stadium quality lighting.

Best to use BI motion detection. And if that doesn't work, then yes you can use another cam to trigger for LPR, but that will also take trial and error cause it could be a couple second delay.

That’s good news on using another cam to trigger. Just need a few hints on how it’s done.

Those IVS examples were just a few of many many tries. If I use larger ones I get the street traffic which I’m trying to avoid

 

[wittaj]

In my case, my spotter camera needs to trigger about 150 feet before the LPR field of view, and if you want both directions then you need 2 spotter cams.

Better way would be to us Code Project to look for a plate and only trigger when plate is seen.

 

[Ri22o]

That’s good news on using another cam to trigger. Just need a few hints on how it’s done.

Those IVS examples were just a few of many many tries. If I use larger ones I get the street traffic which I’m trying to avoid

You would put the LPR cam in a group by itself.
On the Trigger page of the Spotter cam, you will check Trigger Camera Groups and then select the group made above.
When the Spotter is triggered, regardless of what triggered it, it will trigger the LPR. So this Spotter will basically need to be dedicated to only vehicles.

The other option is as above. Use Code Project to analyze the images and only give alerts for the ones that have a plate, regardless of whether it is a car or a person.

 

[prsmith777]

You would put the LPR cam in a group by itself.
On the Trigger page of the Spotter cam, you will check Trigger Camera Groups and then select the group made above.
When the Spotter is triggered, regardless of what triggered it, it will trigger the LPR. So this Spotter will basically need to be dedicated to only vehicles.

The other option is as above. Use Code Project to analyze the images and only give alerts for the ones that have a plate, regardless of whether it is a car or a person.

Thanks for this.

I am using the spotter cam as an overview for the delivery code project model. It works great for picking up delivery vehicles. So I would probably clone this cam and use it only for triggering the LPR cam.

Curious why it would take so much time for a spotter cam to trigger the LPR cam? Are we talking a few seconds or more? Because I can always add pretrigger time on the AI to catch it

 

[Ri22o]

I don't think you would need to clone it unless you're wanting to sort your IVS triggers into certain BI camera rules that can't be done within the settings for one camera.

 

[wittaj]

IP cameras have an inherent lag, so if the field of views are close, by the time the spotter triggers, the object is out of the LPR field of view.

 

[prsmith777]

IP cameras have an inherent lag, so if the field of views are close, by the time the spotter triggers, the object is out of the LPR field of view.

Unfortunately the field of views are close. This may not work after all.

My family thinks Im crazy driving up and down the driveway all the time trying to get this right.

Ive never spent the time to learn the details of BI motion. Ive always used default or IVS on the cam. Guess I'll give it a go. I need to mask out that road.

 

[wittaj]

Yeah I wouldn't clone. Many here, including me, see some weird things when trying to clone for LPR purposes. It tends to process the first camera before acting on the clone and then the plate is missed.

 

[prsmith777]

Update:

Didnt seem to take me that long to set up BI motion with crossing two zones and it works well. I can filter out the traffic on the road by using a larger minimum object size. It seems to trigger more quickly than IVS. I was able to reduce the pre and post trigger images on the AI and still get good results.

 

[AP514]

Do Show how you set it up. It may help someone down the road with a same issue.

 

[wittaj]

Update:

Didnt seem to take me that long to set up BI motion with crossing two zones and it works well. I can filter out the traffic on the road by using a larger minimum object size. It seems to trigger more quickly than IVS. I was able to reduce the pre and post trigger images on the AI and still get good results.

Yep, I make the min object size during the day almost the size of a vehicle and that eliminates most false triggers.

Then at night, since my image is black, my min object size is just smaller than a plate and a rarely get a false trigger - an occasional bug that flies by too close to the camera, but that is rare.

 

[prsmith777]

Yep, I make the min object size during the day almost the size of a vehicle and that eliminates most false triggers.

Then at night, since my image is black, my min object size is just smaller than a plate and a rarely get a false trigger - an occasional bug that flies by too close to the camera, but that is rare.

Wait. you can set them up under night and day profiles? ... ok got to go figure that out now.

 

[wittaj]

Wait. you can set them up under night and day profiles? ... ok got to go figure that out now.

In BI yes. I have a day profile and night profile

 

[prsmith777]

Yep, I make the min object size during the day almost the size of a vehicle and that eliminates most false triggers.

Then at night, since my image is black, my min object size is just smaller than a plate and a rarely get a false trigger - an occasional bug that flies by too close to the camera, but that is rare.

How do you determine the pixel size of the license plate by looking at a clip in BI?

 

[wittaj]

I had someone stop a car in the center of the image and drew a box about the size of the plate.