LPR Camera Help

B

blounsbury

n3wb
Mar 22, 2023
6
1
Phoenix, AZ
Hi folks,

After a recent break in where we couldn’t identify the license plate we decided to add an LPR camera. I’ve researched and it says I should be within 30 degrees on the vertical axis and within 15 degrees on the horizontal axis. The vertical axis isn’t a problem, but the horizontal one is. My house is setback 40 feet from the road and 54 feet to the middle of the road I would need to target. Using some trigonometry, that gives me a minimum capture distance of 208 feet (54/sin(15)) from the camera.

While that street is long enough to do that (and it actually kind of provides better coverage), I’m not sure the Loryta IPC-HFW5241E-Z12E I have will do it at that range. The camera specs have a DORI identify value of 289ft, but 200ft is pushing it for LPR based on what I’ve read (and the Amazon page says LPR at 120-140ft).

I don’t have a way to get this closer to the street, so I have 3 options:
1. Target 208 feet, and hope for the best.
2. Target 115ft (between 115 and 160 is blocked by a fence), but that gives me an angle of 28 degrees - seems likely to be too far off angle to work.
3. Find a different camera with longer range (any suggestions?)
 
People have made the Z12 work at 220 feet with additional IR added.

I can get clean captures at 175 feet with just the built in IR and a dark place with no streetlights.

Folks have been able to get plates at less than ideal angles. I am at 35-40 degrees and the camera is 35 feet above the street. The further the distance, the more you can get away with.

The only other camera you could get with more zoom would be a PTZ but those can be problematic due to focus issues. You would have to run 24/7 black and white or have a generous schedule set up to go B/W with infrared well before sunset.

But since you have the Z12E give a shot!

Let us know.


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Rave to OpenALPR - A World Record?

We are always talking about angles, the best angles to get plate captures etc. I think I must have captured the world record, well it was actually OpeanALPR that did it. Take a look at this - it did get the number correct. Using your human eyes take a guess at the plate number.
ipcamtalk.com ipcamtalk.com
 
Last edited:
Don't let the angles and such worry you too much. Here are three of mine.
Picture 1 is approximately 80 feet and 45 degree angle with a 437 ANPR.
Picture 2 is approximately 140 feet and 25 degree angle with a 5241.
Picture 3 is the same angle as picture 1, just the same car from picture 2 and using the 5241.
 

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Timokreon said:
Don't let the angles and such worry you too much. Here are three of mine.
Picture 1 is approximately 80 feet and 45 degree angle with a 437 ANPR.
Picture 2 is approximately 140 feet and 25 degree angle with a 5241.
Picture 3 is the same angle as picture 1, just the same car from picture 2 and using the 5241.
Click to expand...

@Timokreon How are you determining angle in each case?
 
+1 above - just try it - it either works or not.

Keep in mind many of that published angle literature is based on actual ANPR cameras that read and log the plates and as such their optical focal lengths are not as large (in many instances nowhere near the optical zoom of the Z12E) so they can't get away with as much of an angle as someone that is shooting further out.
 
blounsbury said:
Hi folks,

After a recent break in where we couldn’t identify the license plate we decided to add an LPR camera. I’ve researched and it says I should be within 30 degrees on the vertical axis and within 15 degrees on the horizontal axis. The vertical axis isn’t a problem, but the horizontal one is. My house is setback 40 feet from the road and 54 feet to the middle of the road I would need to target. Using some trigonometry, that gives me a minimum capture distance of 208 feet (54/sin(15)) from the camera.

While that street is long enough to do that (and it actually kind of provides better coverage), I’m not sure the Loryta IPC-HFW5241E-Z12E I have will do it at that range. The camera specs have a DORI identify value of 289ft, but 200ft is pushing it for LPR based on what I’ve read (and the Amazon page says LPR at 120-140ft).

I don’t have a way to get this closer to the street, so I have 3 options:
1. Target 208 feet, and hope for the best.
2. Target 115ft (between 115 and 160 is blocked by a fence), but that gives me an angle of 28 degrees - seems likely to be too far off angle to work.
3. Find a different camera with longer range (any suggestions?)
Click to expand...


#2, you'll be fine
 
Use a DLSR or even a cell phone cam to take photos of passing cars to see if the plates are too foreshortened.

See this thread that goes though the planning and scoping of LPR:

LPR Case Study: Scoping, Planning, Proof of Concept, Installation, & Results

Introduction This thread is about my journey into LPR (License Plate Recognition) after having about 18 months of experience with IP cams and having quite a bit of my system finished. I am not an expert on LPR, or IP cameras either. But I have spent a lot of time working with my system and...
ipcamtalk.com ipcamtalk.com
 
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