IPC-LPR437B-IR / IPC-LPR237B-IR @ Night

[Robert G.]

I have both of these cameras, purchased from @EMPIRETECANDY.

I am getting good results during the day, plates are captured no issues.

At night, I basically get nothing.

Today I took some 'snaps' in the GUI as cars are going past. I assumed that they were blurry or there was some issue and that is why it was not recording any plates at night.

The quality of the plate images at night can be excellent (not every time, but often). I will attach some photos below.

Does anyone know why the camera would not be recognizing the plates? If I was sending this feed into OpenALPR for sure it would grab the plate numbers from these frames, there must be some setting I have done incorrectly that it is ignoring these.

 

[Robert G.]

Just in case anyone else finds this thread looking for solutions. I have found that these cameras must 'see' a vehicle before looking for a plate.

In the past with OpenALPR, you want to get the best shot of the plate possible, that usually means reducing the exposure down so you just see a plate floating along in the dark. No need to even see the vehicle.

With these two camera models, the photo must be bright enough to 'see' something that the camera thinks is a vehicle. Only then does it start scanning for plates.

Here is a photo where it is light enough that the camera sees the vehicle & then recognizes the plate number.

 

[Timokreon]

I was wondering if that was the cause. I asked a similar question in the 237 thread and didn't receive a response.. basically if the picture needs to see the vehicle or not.

Getting the settings correct on the 437 has been tricky. I'm waiting for wildcat's review and setup tips to see if that will help my situation.
My pictures are a lot better than they were, but still miss a vehicle here and there.

 

[Wildcat_1]

The traffic cams benefit from vehicle in FOV BUT do NOT need a vehicle to process a plate (AI cams using Video Metadata do as I've stated before). I've shown this a number of times and just repeated a quick test with me introducing a plate by hand into a shot on the 437 and it recognizes the plate with of course no vehicle, just my hand present

 

[Robert G.]

The traffic cams benefit from vehicle in FOV BUT do NOT need a vehicle to process a plate. I've shown this a number of times and just repeated a quick test with me introducing a plate by hand into a shot on the 437 and it recognizes the plate with of course no vehicle, just my hand present

Very strange. I can go an entire night and not get a single plate, if I make it too dark that only the plate can be seen. If I brighten it up a bit (the plates look WORSE) and it can see the vehicles then it can capture the plate.

Another thing I changed was Vehicle Detection Sensitivity (on AI Settings tab). If I set that low, it will not detect any vehicles and not detect any plates. I crank it up to 100 and it will detect just about anything as a potential vehicle and then plate recognition works (in the daytime that testing was done).

 

[Wildcat_1]

Very strange. I can go an entire night and not get a single plate, if I make it too dark that only the plate can be seen. If I brighten it up a bit (the plates look WORSE) and it can see the vehicles then it can capture the plate.

Another thing I changed was Vehicle Detection Sensitivity (on AI Settings tab). If I set that low, it will not detect any vehicles and not detect any plates. I crank it up to 100 and it will detect just about anything as a potential vehicle and then plate recognition works (in the daytime that testing was done).

Yes, you do have to dial in the traffic cams differently due to the way they process a plate. The plate matching algorithms are different on the DB loaded cams such as traffic cams vs the AI video metadata cams. Sensitivity does make an impact as you've seen BUT that does NOT change confidence level of the plate, that should still be accurately displayed for you in realtime (when you use Live view you can see the CL level change as its processing the scene). It may go without saying but I'll state it for others that may not be familiar with LPR/NPR and especially ALPR/ANPR is that angle, height, distance to target, light on FOV and speed of target (for shutter speed adjustment) is critical here. Not sure what your install looks like but can certainly DM me with details if you would like some feedback, happy to help where I can. The 4MP (437) is also a different animal from the 237 in terms of dialing in, thats for sure. I'm currently in process of reviewing this camera for the Dahua sub-forum and have put it (and its 237 brother before) through its paces. This time, I'm really pushing the angle of approach to ridiculous levels to test the camera out. As part of this I will share the settings I use so that others can hopefully benefit in their deployments. As I said though, this does require a different element of dialing in vs the 237. While the 4MP sensor is tried and true (as seen in many of the other cams I've tested), for ALPR/ANPR this one needs some love, but give it that and it can and does shine at night. There are also a number of settings that should NOT be used as they really only help in the perfect install (think barrier control or dead stop choke point). The 886 plate capture definitely needs more zoom there but with dialing that in a little more I would expect (based on zoom adjustment) that you should get a plate hit on that. What was your shutter speed ? Maybe not for the open thread but if you want to DM me some pics of the install and light on scene at night, I'll take a look when I can. Working with others on their cams at the moment but will get back to you and as I said, happy to help if I can.

HTH

 

[Timokreon]

Just curious, I'm sure you've answered this else where wildcat, but do you see any difference on ability to pick up plates in plate color?
I think part of my misses are the newer plates that are printed rather than stamped, as documented in the Tennessee thread.