New to LPR? Considerations Before You Begin

chyatt21 said:
Is sighthound a subscription? Also is if software that can be downloaded, or cloud based only?
Click to expand...
They have both an on premise and cloud solution. The cloud pricing has usage tiers, which I think the free tier is 5,000 per month. I’m only doing my driveway, so that is plenty.
 
samplenhold said:
Thought I would throw together a post on my experiences so far with LPR in an effort to help others that are considering running down that rabbit hole. There are some practical considerations you should know about LPR. I am approaching this from the position of using Blue Iris and Plate Recognizer Snapshot as that is what I have done so far. If you are using an NVR or some other plate OCR, then some of the discussion may not apply to you.


Plate Recognizer (PR) is very easy to set up in Blue Iris (BI). It uses the Alert image from the trigger alert in BI. BI sends that Alert image to PR and PR returns the plate number to BI. It gets written to the BI log file.


LPR is part science and part art. I see so many posts on IPCAMTALK by newbies, usually during their introduction post, where they state they are going to set up a bunch of cams, including LPR, right off the bat. Most state that they want to use one cam to get an overview of the street and get plates with it also. Of course, we always state that in most cases, a cam for LPR should only be used for LPR. This is usually stated since reading plates requires the cam to be quite zoomed in to the street and at night it needs fast shutter speeds and lots of IR such that the only thing that is not totally black is the plate and the car lights.
View attachment 74787
But what about all of the other considerations for LPR?

I started down this path at the end of 2019, after most of my cam plan was finished. First thing to consider was ‘what do I hope to accomplish with LPR?’ I live on a corner in a subdivision north of Houston Texas, outside of the city limits. The corner is a ‘T’ intersection with the top of the ‘T’ running NE/SW in front of my house and the base of the ‘T’ running NW/SE alongside of my house. I was hoping to get as many plates as possible and have a way to store the plate numbers along with date, time and other info that would allow me to search for a plate to see when it passed by. Texas is a two-plate state. Most vehicles, but not all, have both a rear and a front plate. If I focus a single cam on the intersection, I would miss a lot of plates if the car did not have a front plate. So I decided on two cams, one pointed at the intersection and one pointed down the road running in front but to the SW. I have called these cams LPR-E (intersection facing NE) and LPR-W (facing down the road to the SW).
View attachment 74780View attachment 74779

It took me quite a while to find the most appropriate place to put the cams. I sat out on the front porch, took many pictures and walked the street thinking of where to place them. I used Google Maps and the IPVM Calculator to help with the design. I wanted something that would blend in and not scream CAMERAS HERE! So I decided to build a box to house the cams and place it in the garden behind a pine tree. I looked at all of the threads in the LPR sub forum and knew that the big issues facing me were distance and angle. Would that spot work for me? So I stood at the tree and took pictures of cars coming by. Zooming in on the plates from those stills looked promising.

View attachment 74778 View attachment 74793 View attachment 74794

So I bought one Dahua HFW5241E-Z12E which was the current cam in the prosumer line that was being used for LPR. It has enough zoom (5-60mm) for my locations based on the IVPM Calculator. I set it on a box behind the tree and let it capture video in both directions and it looked good, I could read them. I sent stills from the video to Plate Recognizer and they all were read just fine by it. So I was encouraged and bought the second cam.
View attachment 74788View attachment 74789

This is the setup as shown in the IPVM Calculator. LPR-E angle is about 26 degrees and distances are 40-150’. LPR-W angle is about 36 degrees and distances are 70-130’.

View attachment 74772

So on this design, the only plates I will not get are it the vehicle does not have a front plate and they make the turn onto the NE part of the ‘T’.

I won’t go into the running of cable and building the box. Maybe I will do another post covering that. But below is the cam box and some shots showing the placement and views of the street.
View attachment 74769View attachment 74781View attachment 74782

Considerations:

ANGLE
The angle will set how much your plate is foreshortened. This to me is the issue that impacts how well OCR does on reading the plate. In using PR, the more at an angle the plate is the less the accuracy is. PR has a hard time with M, H, N, W, Y, V, 6, G, and T. Also T, I, 1, and 0 vs O. At least for the Texas fonts. But if the angle is close to zero, it has no issue. This is mostly a problem at night, but I have seen this issue during the day also.

Was read by PR as CTI2357
View attachment 74770
But this view was read correctly by PR as CTT2357
View attachment 74771
This was read as DHL2683 but is really DML2683
View attachment 74773

DISTANCE
The further away the plate, the harder it is to read. However, the farther down the road, the lower the angle. So with the proper zoom, it can help minimize foreshortening.

SPEED
To get a plate that you can read requires fast shutter speeds, like 1/2000sec. That is needed to ‘freeze’ the plate. The faster the car, the less likely you will get a non-blurry plate. FPS has NOTHING to do with it. It is totally shutter speed and Iris. No different than sports photography. The speed also impacts getting a trigger alert and the position of the vehicle in the snapshot. So depending on the speed, the plate may or may not be in the frame.

Too slow to get plate in frame
View attachment 74790

ZOOM and FOV
The zoom and FOV go hand in hand for impacting the success of the plate capture. Too little zoom and the plate is too small to read. Too much zoom and the FOV is such that the car fills the whole frame and the trigger may not work or the plate is not in the frame.

LIGHTING
The sun can be your friend, but it can also kill a plate cap. It can overexpose the plate and make it unreadable.
View attachment 74792
At night, even though you are using IR, conventional lighting does play a part. I did not realize this until @Wildcat_1 posted his night review of the 5442 cams where he showed IR only, conventional light only, and both. I am lucky in that I have two street lights near the corner and one down the road. These do help get decent night time shots.
View attachment 74791 View attachment 74784 View attachment 74785

DIRECTION OF TRAVEL
This may seem trivial, but the direction of travel impacts the quality also. Plates coming towards the cam seem to blur more that plates going away from the cam especially during dusk and dawn. Of course, this could just be that the plates coming towards the cam are front plates and are not illuminated.

OTHER
Obviously you need to have very different cam exposure settings for day and night. Every cam location is different and what works for one, may not work for another. I started with the values listed by @bigredfish and @wittaj and adjusted from there. I was surprised how little tweaking I need to do to get good, consistent caps. Dusk and dawn are particularly more difficult.
View attachment 74776 View attachment 74775 View attachment 74777

I set my cams to go to night about 50 minutes before dark and keep it in night mode 50 minutes after it gets light in the morning. This stops any focusing issues that most folks have complained about.

Paper plates and other non-reflecting plates are hard to get at night. Sometimes I get them and sometimes I do not. Also, the police seem to have some kind of coating that does not allow for a cap at night.
View attachment 74786

Dirty and damaged plates can be hard to get. Another issue is items that block the plate, like hitch balls and bike racks.
View attachment 74768

Some states have multiple lines on their plates. PR does not do well with those.
View attachment 74783 PR missed the 'U' on this plate.

Front plates are great! But even though Texas requires a front plate and the fine is $500, many do not. Like, what’s up with Audis? They almost NEVER have a front plate.
View attachment 74767

BLUE IRIS
Getting your trigger settings will be very important if you want to use a plate OCR service. With PR it is free for 2500 lookups per month but has other pricing such as $50/month for 50,000 lookups per month. A lookup is any image that is sent to PR, even if there is no plate in it. In my first four days of using PR, I had over 2000 lookups. That is about 500 lookups per day. For one day that I really worked the data on, of those 500 lookups only 281 returned a plate value. So about 44% were worthless alerts. Looking at those, it is apparent that I need to do better in using triggers. While I have gotten good input here, like about cloning the cam and using one clone for one direction and another clone for the other direction, I have not had the time to try it out. Another issue is non vehicles triggering the cam, like people, dogs, and golf carts. Probably will have to live with those.
View attachment 74774

PLATE RECOGNIZER
There are issues that I have with PR. There is no way to correct plate numbers. There is no easy way to download your captures. I asked PR about that and they sent me some info on using WebHooks to do it. I have not programmed in scripts or anything else in over 10 years. PR does write the plate, camera, date, and time to BI’s log file, but pulling that out so far has been a big deal. I have already mentioned that it has a hard time differentiating certain letters and numbers. Also, sometimes it picks up my camera name or time/date as a plate. Or lettering on the side of a vehicle. PR also has a service called Stream which is $35/month per camera. It uses the camera's video stream rather than an alert snapshot. So this may negate the need to fine tune the trigger. They have a 30 day free trial for three cams, so maybe some day I will try it out.

DATABASE
I had thought I could build some kind of searchable database for all of the plate data I am collecting. Even something as simple as an Excel spreadsheet might suffice. But so far getting data from PR into that is a nightmare.

OTHER PLATE OCRs
A lot of members use OPENALPR and @Gymratz and @DLONG2 and others have written interfaces for the data in that service. But it seems that that service changes their formatting often which breaks things and causes those guys to figure it out and make updates. But it is not right to expect them to continue to support that effort with no compensation. I plan on trying it out some day. But I just do not have the time right now.

Maybe I will just do like @bigredfish and not worry about collecting the plate data and just know that if something happens, I can look back and probably get a plate.

Well I hope this helps anyone that is thinking of trying out LPR. Please feel free to make comments and suggestions.
Click to expand...
Thank you for sharing your excellent work. My first two purchases with CCTV Camera Pros resulted in both HVRs blue screened the first in 3 hrs and the second after 48 hours. My 3system from SCW was misrepresented as the lied about having PR software thru àn affiliate. The cameras were good for area observation but rarely works for LPR and never at night even tho I had angles !ess Iithan 30, short distances and slow small cul-de-sac speeds. Ironically their observation camera thwarted an attempted burglary first few days I installed. If their HVR accepted other cameras I could just keep the cameras and find another camera. May I pay you for a telephone consult? Doug Embrey old dumb retired lawyer!
 
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I definitely would not do anything on here for payment. If you would like to ask questions here, start a thread with specific questions. If you just want some input, you can PM me on this forum.
 
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samplenhold said:
Thought I would throw together a post on my experiences so far with LPR in an effort to help others that are considering running down that rabbit hole. There are some practical considerations you should know about LPR. I am approaching this from the position of using Blue Iris and Plate Recognizer Snapshot as that is what I have done so far. If you are using an NVR or some other plate OCR, then some of the discussion may not apply to you.


Plate Recognizer (PR) is very easy to set up in Blue Iris (BI). It uses the Alert image from the trigger alert in BI. BI sends that Alert image to PR and PR returns the plate number to BI. It gets written to the BI log file.


LPR is part science and part art. I see so many posts on IPCAMTALK by newbies, usually during their introduction post, where they state they are going to set up a bunch of cams, including LPR, right off the bat. Most state that they want to use one cam to get an overview of the street and get plates with it also. Of course, we always state that in most cases, a cam for LPR should only be used for LPR. This is usually stated since reading plates requires the cam to be quite zoomed in to the street and at night it needs fast shutter speeds and lots of IR such that the only thing that is not totally black is the plate and the car lights.
View attachment 74787
But what about all of the other considerations for LPR?

I started down this path at the end of 2019, after most of my cam plan was finished. First thing to consider was ‘what do I hope to accomplish with LPR?’ I live on a corner in a subdivision north of Houston Texas, outside of the city limits. The corner is a ‘T’ intersection with the top of the ‘T’ running NE/SW in front of my house and the base of the ‘T’ running NW/SE alongside of my house. I was hoping to get as many plates as possible and have a way to store the plate numbers along with date, time and other info that would allow me to search for a plate to see when it passed by. Texas is a two-plate state. Most vehicles, but not all, have both a rear and a front plate. If I focus a single cam on the intersection, I would miss a lot of plates if the car did not have a front plate. So I decided on two cams, one pointed at the intersection and one pointed down the road running in front but to the SW. I have called these cams LPR-E (intersection facing NE) and LPR-W (facing down the road to the SW).
View attachment 74780View attachment 74779

It took me quite a while to find the most appropriate place to put the cams. I sat out on the front porch, took many pictures and walked the street thinking of where to place them. I used Google Maps and the IPVM Calculator to help with the design. I wanted something that would blend in and not scream CAMERAS HERE! So I decided to build a box to house the cams and place it in the garden behind a pine tree. I looked at all of the threads in the LPR sub forum and knew that the big issues facing me were distance and angle. Would that spot work for me? So I stood at the tree and took pictures of cars coming by. Zooming in on the plates from those stills looked promising.

View attachment 74778 View attachment 74793 View attachment 74794

So I bought one Dahua HFW5241E-Z12E which was the current cam in the prosumer line that was being used for LPR. It has enough zoom (5-60mm) for my locations based on the IVPM Calculator. I set it on a box behind the tree and let it capture video in both directions and it looked good, I could read them. I sent stills from the video to Plate Recognizer and they all were read just fine by it. So I was encouraged and bought the second cam.
View attachment 74788View attachment 74789

This is the setup as shown in the IPVM Calculator. LPR-E angle is about 26 degrees and distances are 40-150’. LPR-W angle is about 36 degrees and distances are 70-130’.

View attachment 74772

So on this design, the only plates I will not get are it the vehicle does not have a front plate and they make the turn onto the NE part of the ‘T’.

I won’t go into the running of cable and building the box. Maybe I will do another post covering that. But below is the cam box and some shots showing the placement and views of the street.
View attachment 74769View attachment 74781View attachment 74782

Considerations:

ANGLE
The angle will set how much your plate is foreshortened. This to me is the issue that impacts how well OCR does on reading the plate. In using PR, the more at an angle the plate is the less the accuracy is. PR has a hard time with M, H, N, W, Y, V, 6, G, and T. Also T, I, 1, and 0 vs O. At least for the Texas fonts. But if the angle is close to zero, it has no issue. This is mostly a problem at night, but I have seen this issue during the day also.

Was read by PR as CTI2357
View attachment 74770
But this view was read correctly by PR as CTT2357
View attachment 74771
This was read as DHL2683 but is really DML2683
View attachment 74773

DISTANCE
The further away the plate, the harder it is to read. However, the farther down the road, the lower the angle. So with the proper zoom, it can help minimize foreshortening.

SPEED
To get a plate that you can read requires fast shutter speeds, like 1/2000sec. That is needed to ‘freeze’ the plate. The faster the car, the less likely you will get a non-blurry plate. FPS has NOTHING to do with it. It is totally shutter speed and Iris. No different than sports photography. The speed also impacts getting a trigger alert and the position of the vehicle in the snapshot. So depending on the speed, the plate may or may not be in the frame.

Too slow to get plate in frame
View attachment 74790

ZOOM and FOV
The zoom and FOV go hand in hand for impacting the success of the plate capture. Too little zoom and the plate is too small to read. Too much zoom and the FOV is such that the car fills the whole frame and the trigger may not work or the plate is not in the frame.

LIGHTING
The sun can be your friend, but it can also kill a plate cap. It can overexpose the plate and make it unreadable.
View attachment 74792
At night, even though you are using IR, conventional lighting does play a part. I did not realize this until @Wildcat_1 posted his night review of the 5442 cams where he showed IR only, conventional light only, and both. I am lucky in that I have two street lights near the corner and one down the road. These do help get decent night time shots.
View attachment 74791 View attachment 74784 View attachment 74785

DIRECTION OF TRAVEL
This may seem trivial, but the direction of travel impacts the quality also. Plates coming towards the cam seem to blur more that plates going away from the cam especially during dusk and dawn. Of course, this could just be that the plates coming towards the cam are front plates and are not illuminated.

OTHER
Obviously you need to have very different cam exposure settings for day and night. Every cam location is different and what works for one, may not work for another. I started with the values listed by @bigredfish and @wittaj and adjusted from there. I was surprised how little tweaking I need to do to get good, consistent caps. Dusk and dawn are particularly more difficult.
View attachment 74776 View attachment 74775 View attachment 74777

I set my cams to go to night about 50 minutes before dark and keep it in night mode 50 minutes after it gets light in the morning. This stops any focusing issues that most folks have complained about.

Paper plates and other non-reflecting plates are hard to get at night. Sometimes I get them and sometimes I do not. Also, the police seem to have some kind of coating that does not allow for a cap at night.
View attachment 74786

Dirty and damaged plates can be hard to get. Another issue is items that block the plate, like hitch balls and bike racks.
View attachment 74768

Some states have multiple lines on their plates. PR does not do well with those.
View attachment 74783 PR missed the 'U' on this plate.

Front plates are great! But even though Texas requires a front plate and the fine is $500, many do not. Like, what’s up with Audis? They almost NEVER have a front plate.
View attachment 74767

BLUE IRIS
Getting your trigger settings will be very important if you want to use a plate OCR service. With PR it is free for 2500 lookups per month but has other pricing such as $50/month for 50,000 lookups per month. A lookup is any image that is sent to PR, even if there is no plate in it. In my first four days of using PR, I had over 2000 lookups. That is about 500 lookups per day. For one day that I really worked the data on, of those 500 lookups only 281 returned a plate value. So about 44% were worthless alerts. Looking at those, it is apparent that I need to do better in using triggers. While I have gotten good input here, like about cloning the cam and using one clone for one direction and another clone for the other direction, I have not had the time to try it out. Another issue is non vehicles triggering the cam, like people, dogs, and golf carts. Probably will have to live with those.
View attachment 74774

PLATE RECOGNIZER
There are issues that I have with PR. There is no way to correct plate numbers. There is no easy way to download your captures. I asked PR about that and they sent me some info on using WebHooks to do it. I have not programmed in scripts or anything else in over 10 years. PR does write the plate, camera, date, and time to BI’s log file, but pulling that out so far has been a big deal. I have already mentioned that it has a hard time differentiating certain letters and numbers. Also, sometimes it picks up my camera name or time/date as a plate. Or lettering on the side of a vehicle. PR also has a service called Stream which is $35/month per camera. It uses the camera's video stream rather than an alert snapshot. So this may negate the need to fine tune the trigger. They have a 30 day free trial for three cams, so maybe some day I will try it out.

DATABASE
I had thought I could build some kind of searchable database for all of the plate data I am collecting. Even something as simple as an Excel spreadsheet might suffice. But so far getting data from PR into that is a nightmare.

OTHER PLATE OCRs
A lot of members use OPENALPR and @Gymratz and @DLONG2 and others have written interfaces for the data in that service. But it seems that that service changes their formatting often which breaks things and causes those guys to figure it out and make updates. But it is not right to expect them to continue to support that effort with no compensation. I plan on trying it out some day. But I just do not have the time right now.

Maybe I will just do like @bigredfish and not worry about collecting the plate data and just know that if something happens, I can look back and probably get a plate.

Well I hope this helps anyone that is thinking of trying out LPR. Please feel free to make comments and suggestions.
Click to expand...
I am so appreciative of your treatise here. I am returning the SCW order and would appreciate the model numbers and what equip you used and where I order it from. I have the Diahua camera order number you listed above or should i get a newer model?
 
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samplenhold said:
Thought I would throw together a post on my experiences so far with LPR in an effort to help others that are considering running down that rabbit hole. There are some practical considerations you should know about LPR. I am approaching this from the position of using Blue Iris and Plate Recognizer Snapshot as that is what I have done so far. If you are using an NVR or some other plate OCR, then some of the discussion may not apply to you.


Plate Recognizer (PR) is very easy to set up in Blue Iris (BI). It uses the Alert image from the trigger alert in BI. BI sends that Alert image to PR and PR returns the plate number to BI. It gets written to the BI log file.


LPR is part science and part art. I see so many posts on IPCAMTALK by newbies, usually during their introduction post, where they state they are going to set up a bunch of cams, including LPR, right off the bat. Most state that they want to use one cam to get an overview of the street and get plates with it also. Of course, we always state that in most cases, a cam for LPR should only be used for LPR. This is usually stated since reading plates requires the cam to be quite zoomed in to the street and at night it needs fast shutter speeds and lots of IR such that the only thing that is not totally black is the plate and the car lights.
View attachment 74787
But what about all of the other considerations for LPR?

I started down this path at the end of 2019, after most of my cam plan was finished. First thing to consider was ‘what do I hope to accomplish with LPR?’ I live on a corner in a subdivision north of Houston Texas, outside of the city limits. The corner is a ‘T’ intersection with the top of the ‘T’ running NE/SW in front of my house and the base of the ‘T’ running NW/SE alongside of my house. I was hoping to get as many plates as possible and have a way to store the plate numbers along with date, time and other info that would allow me to search for a plate to see when it passed by. Texas is a two-plate state. Most vehicles, but not all, have both a rear and a front plate. If I focus a single cam on the intersection, I would miss a lot of plates if the car did not have a front plate. So I decided on two cams, one pointed at the intersection and one pointed down the road running in front but to the SW. I have called these cams LPR-E (intersection facing NE) and LPR-W (facing down the road to the SW).
View attachment 74780View attachment 74779

It took me quite a while to find the most appropriate place to put the cams. I sat out on the front porch, took many pictures and walked the street thinking of where to place them. I used Google Maps and the IPVM Calculator to help with the design. I wanted something that would blend in and not scream CAMERAS HERE! So I decided to build a box to house the cams and place it in the garden behind a pine tree. I looked at all of the threads in the LPR sub forum and knew that the big issues facing me were distance and angle. Would that spot work for me? So I stood at the tree and took pictures of cars coming by. Zooming in on the plates from those stills looked promising.

View attachment 74778 View attachment 74793 View attachment 74794

So I bought one Dahua HFW5241E-Z12E which was the current cam in the prosumer line that was being used for LPR. It has enough zoom (5-60mm) for my locations based on the IVPM Calculator. I set it on a box behind the tree and let it capture video in both directions and it looked good, I could read them. I sent stills from the video to Plate Recognizer and they all were read just fine by it. So I was encouraged and bought the second cam.
View attachment 74788View attachment 74789

This is the setup as shown in the IPVM Calculator. LPR-E angle is about 26 degrees and distances are 40-150’. LPR-W angle is about 36 degrees and distances are 70-130’.

View attachment 74772

So on this design, the only plates I will not get are it the vehicle does not have a front plate and they make the turn onto the NE part of the ‘T’.

I won’t go into the running of cable and building the box. Maybe I will do another post covering that. But below is the cam box and some shots showing the placement and views of the street.
View attachment 74769View attachment 74781View attachment 74782

Considerations:

ANGLE
The angle will set how much your plate is foreshortened. This to me is the issue that impacts how well OCR does on reading the plate. In using PR, the more at an angle the plate is the less the accuracy is. PR has a hard time with M, H, N, W, Y, V, 6, G, and T. Also T, I, 1, and 0 vs O. At least for the Texas fonts. But if the angle is close to zero, it has no issue. This is mostly a problem at night, but I have seen this issue during the day also.

Was read by PR as CTI2357
View attachment 74770
But this view was read correctly by PR as CTT2357
View attachment 74771
This was read as DHL2683 but is really DML2683
View attachment 74773

DISTANCE
The further away the plate, the harder it is to read. However, the farther down the road, the lower the angle. So with the proper zoom, it can help minimize foreshortening.

SPEED
To get a plate that you can read requires fast shutter speeds, like 1/2000sec. That is needed to ‘freeze’ the plate. The faster the car, the less likely you will get a non-blurry plate. FPS has NOTHING to do with it. It is totally shutter speed and Iris. No different than sports photography. The speed also impacts getting a trigger alert and the position of the vehicle in the snapshot. So depending on the speed, the plate may or may not be in the frame.

Too slow to get plate in frame
View attachment 74790

ZOOM and FOV
The zoom and FOV go hand in hand for impacting the success of the plate capture. Too little zoom and the plate is too small to read. Too much zoom and the FOV is such that the car fills the whole frame and the trigger may not work or the plate is not in the frame.

LIGHTING
The sun can be your friend, but it can also kill a plate cap. It can overexpose the plate and make it unreadable.
View attachment 74792
At night, even though you are using IR, conventional lighting does play a part. I did not realize this until @Wildcat_1 posted his night review of the 5442 cams where he showed IR only, conventional light only, and both. I am lucky in that I have two street lights near the corner and one down the road. These do help get decent night time shots.
View attachment 74791 View attachment 74784 View attachment 74785

DIRECTION OF TRAVEL
This may seem trivial, but the direction of travel impacts the quality also. Plates coming towards the cam seem to blur more that plates going away from the cam especially during dusk and dawn. Of course, this could just be that the plates coming towards the cam are front plates and are not illuminated.

OTHER
Obviously you need to have very different cam exposure settings for day and night. Every cam location is different and what works for one, may not work for another. I started with the values listed by @bigredfish and @wittaj and adjusted from there. I was surprised how little tweaking I need to do to get good, consistent caps. Dusk and dawn are particularly more difficult.
View attachment 74776 View attachment 74775 View attachment 74777

I set my cams to go to night about 50 minutes before dark and keep it in night mode 50 minutes after it gets light in the morning. This stops any focusing issues that most folks have complained about.

Paper plates and other non-reflecting plates are hard to get at night. Sometimes I get them and sometimes I do not. Also, the police seem to have some kind of coating that does not allow for a cap at night.
View attachment 74786

Dirty and damaged plates can be hard to get. Another issue is items that block the plate, like hitch balls and bike racks.
View attachment 74768

Some states have multiple lines on their plates. PR does not do well with those.
View attachment 74783 PR missed the 'U' on this plate.

Front plates are great! But even though Texas requires a front plate and the fine is $500, many do not. Like, what’s up with Audis? They almost NEVER have a front plate.
View attachment 74767

BLUE IRIS
Getting your trigger settings will be very important if you want to use a plate OCR service. With PR it is free for 2500 lookups per month but has other pricing such as $50/month for 50,000 lookups per month. A lookup is any image that is sent to PR, even if there is no plate in it. In my first four days of using PR, I had over 2000 lookups. That is about 500 lookups per day. For one day that I really worked the data on, of those 500 lookups only 281 returned a plate value. So about 44% were worthless alerts. Looking at those, it is apparent that I need to do better in using triggers. While I have gotten good input here, like about cloning the cam and using one clone for one direction and another clone for the other direction, I have not had the time to try it out. Another issue is non vehicles triggering the cam, like people, dogs, and golf carts. Probably will have to live with those.
View attachment 74774

PLATE RECOGNIZER
There are issues that I have with PR. There is no way to correct plate numbers. There is no easy way to download your captures. I asked PR about that and they sent me some info on using WebHooks to do it. I have not programmed in scripts or anything else in over 10 years. PR does write the plate, camera, date, and time to BI’s log file, but pulling that out so far has been a big deal. I have already mentioned that it has a hard time differentiating certain letters and numbers. Also, sometimes it picks up my camera name or time/date as a plate. Or lettering on the side of a vehicle. PR also has a service called Stream which is $35/month per camera. It uses the camera's video stream rather than an alert snapshot. So this may negate the need to fine tune the trigger. They have a 30 day free trial for three cams, so maybe some day I will try it out.

DATABASE
I had thought I could build some kind of searchable database for all of the plate data I am collecting. Even something as simple as an Excel spreadsheet might suffice. But so far getting data from PR into that is a nightmare.

OTHER PLATE OCRs
A lot of members use OPENALPR and @Gymratz and @DLONG2 and others have written interfaces for the data in that service. But it seems that that service changes their formatting often which breaks things and causes those guys to figure it out and make updates. But it is not right to expect them to continue to support that effort with no compensation. I plan on trying it out some day. But I just do not have the time right now.

Maybe I will just do like @bigredfish and not worry about collecting the plate data and just know that if something happens, I can look back and probably get a plate.

Well I hope this helps anyone that is thinking of trying out LPR. Please feel free to make comments and suggestions.
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P.S. I would like an NVR with POE cables and plug and play.
 
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Doug2 said:
I am so appreciative of your treatise here. I am returning the SCW order and would appreciate the model numbers and what equip you used and where I order it from. I have the Diahua camera order number you listed above or should i get a newer model?
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I have purchased all of my cams from Andy (@EMPIRETECANDY ) and he has answered your questions above. I have never ordered from his Amazon store. I just send him an email and he ships it to me from Hong Kong.

@wittaj gave great input and @biggen is correct also. Unless you are located on a one way street, you would need two cams pointed in different directions to get all plates. As I live on a T-intersection, I really need a third cam as I miss any that do not have a front plate and make the turn onto Side Street.

Realize that the 5241 Z12 cam that I am using is really NOT an LPR cam per se. It is a cam that has a good telephoto lens that can be adjusted to get the FOV one needs for most LPR applications. But there are newer cams that are designed for LPR that you may want to consider. Their lenses are less telephoto, which if your distances are not too great, would be fine. They have a lot of plate processing power. Below is one that is currently being reviewed:

Review: IPC-LPR237B-IR / Equivalent of Dahua ITC237-PW6M-IRLZF1050-B - ANPR, Traffic & Access Control Camera

Who’s up for a new review ? YES ? Ok, lets jump into traffic cams and dedicated ANPR. @EMPIRETECANDY Amazon link HERE Quick Update: @EMPIRETECANDY model of this camera which you should use if ordering from him is IPC-LPR237B-IR. Intro This is a review of the Dahua ITC237 ANPR, traffic and...
ipcamtalk.com ipcamtalk.com

Hope this helps.
 
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billyinhudsonfl said:
Hi Andy.
Are you planning on any Black Friday deals this year (2021) ?
Thanks.
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Fed Ex Ground Shipping Hahaha

Fedex refund us 500usd from last delay. Right now the sea port has badly delay, because of no enough workers to download the container, no enough drivers take the container to leave the harbor.sea Shipping cost increased 10times since 2020. And this cost increase all paid by US normal people...
ipcamtalk.com ipcamtalk.com
 
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EMPIRETECANDY said:
I may do 2 promotion, 1 for black friday, another one at early Dec. Was planned to do one in late Oct, and one in Black Friday, all mess up by the sea port crashed.
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I'll be patient. It doesn't need to be under the tree Dec 25, though my wife will be happy if I tell her I bought my Christmas presents and she just needs to wrap them :)
 
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samplenhold said:
Yes. and thank you for the kind words.


The reason would be to see if a certain plate 'cased' the neighborhood, and if it was during the day, maybe get a better picture of the car and occupants.

I spent some time compiling one full day of plates that passed the cams. That included getting plates for the alerts that did not return a plate and getting them for cars that did not trip an alert at all. Just when you think you have the detection perfect, a few cars go by and no trigger. That was 386 plates. Of course, some of those were cars that were picked up by both cams as they passed in front of the house, but I was surprised by the number of cars that go back and forth, that seem to be just driving around. Like there is this one Mustang that comes and goes and drives through the intersection three times after dark. It is also interesting how many times a police car passes in a day and at what times those are.
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I am SO late to the party. THANK YOU for this awesome thread-- more than enough to get me going. We'll see how great of a deal Andy can do on that cam next week. :)
 
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I'm playing around with LPR and testing AWS Rekognition to read the plates. I downloaded the images that got an error (in 1st post) and tried to see how well Rekognition fared.

Rekognition got it right:

"DHL2683 error.JPG"

Detected text:TEXAS
Confidence: 97.38%
Id: 0
Type:LINE
Detected text: DML -2683
Confidence: 77.80%
Id: 1
Type:LINE


"CTI2357 - error.JPG"

Detected text:TEXAS
Confidence: 65.59%
Id: 0
Type:LINE
Detected text:CTT-2357
Confidence: 93.59%
Id: 1
Type:LINE


Now I need to figure out how to automate the process of getting images to AWS and running rekognition on them. In case you are wondering, it costs $1 for every 1000 images processed by Rekognition (text detection).
 
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