Need Help Clearing Up Axis / Avigilon License Plate Shots

We recently completed an Avigilon conversion for a new customer. Part of our initial install included adding 2 new 5MP cameras in the customer's parking deck. Due to serious budgetary restraints, the customer is trying to capture a fairly large area (overview shot) and also capture legible license plate shots (not LPR). I know that this is typically not a good idea, but we are trying to go above and beyond our customers expectations, and make this happen. I have attampted to get this shot with an Avigilon 5MP camera and also an Axis P1427. I have got better results from the Axis camera. I have a little more versatility with the camera setting in the Axis. The two aspects that have made the biggest difference, is the ability to use the slider bar to balance in between noise and motion blur, and also adjusting the concentration of the IR in the Axis camera. Please let me know if any of you have ran into this before, or have any suggestions to make this scenario any better. Thank you in advance.

Axis P1427

Avigilon 5MP


The first thing I'd try is speeding the exposure. Vehicles often blur using 1/30s exposure, even at relatively slow speeds. Try something like 1/100s or 1/200s. It will darken the scene, but you still might be able to get your overview along with the license plate.

What is the max shutter speed set to? You probably need to go faster to 1/100s, 1/250s or 1/5002 to eliminate blur from the car moving.

Relevant excerpt from our LPC shootout:

Using default settings, only the GV-Hybrid was able to capture the plate, with blur and overexposure obscuring plates on the other two cameras due to their much slower exposure (1/30s vs. 1/500s).

Speeding exposure to 1/500s in the Avigilon and Samsung cameras, the Avigilon H3 bullet is able to capture license plates, though the Samsung SNB-5004 is still extremely overexposed.

....and also adjusting the concentration of the IR in the Axis camera.

This shot appears to have a cut filter engaged, so I'm not sure how much the IR can help.

Have you tried forcing into nightmode? With the IR working, you should have more light and can make the shutter speed faster.

My guess is the customer won't like B/W images for the overview.

FWIW, the Axis plate is legible, barely.

Start by adjusting the exposure on the Avigilon camera to 1/100 and adjust it faster from there.

What Avigilon camera is this dome or bullet? For the future I recommed 3MP analytic bullet cameras for LPR shots. We have many depolyed with great results.

If 1/100 or 1/250 works but is dark in the center you might be able to add white-light leds near the camera (spots).

You might also try an mjpeg stream (might handle the blur better if you are using now h.264 and bandwidth and storage space are not a problem).

We are using some Avigilon 5MP IR bullets and domes to capture license plates in parking and driveway areas and they do general overview double duty as you noted your customer wants to do. One thing I have found is that, as others have mentioned above, adjusting to a shorter exposure length makes a significant improvement in low lighting conditions, though there is definitely a trade off in a darker image. Depending on location, we're using 1/100 sec or 1/125 sec settings. We have found the 1/250 sec setting to be too dark for night use.

Another thing I've found is that pixels per foot is really the primary deciding factor on whether the Avigilon cameras (and others we use) can reliably capture license plates. In all instances where we are capturing license plates (successfully) with the Avigilon cameras, we are using the 9-22mm lens option. During daylight hours, our capture rate at ~100 ft. distance to target is 100% at maximum zoom (~126 ppf according to the handy IPVM calculator) and 7 images per second, and we can reliably (>85%) capture tags out to at least 175 ft. (~72 ppf) during the day. Under optimal lighting conditions we can capture out to 200 ft.

In low light conditions that drops to around 70% at 100 ft. when the cameras switch to night mode, and less than 50% at 125 ft. The greatest challenge when the devices are in night mode is that even at faster exposure times, the tail lights, tag lights, and brake lights can "blind" the camera against a detailed image capture.

Our experience has been that the Avigilon IR bullets (with adaptive IR enabled) are much more effective than the IR domes for this application. Nighttime license plate capture rates for our Avigilon IR domes at 50 ft. is less than 50%, and only around 95% during daylight.

Finally, if the Avigilon camera has WDR we have had issues in the past with "ghosting" (motion blur) that made it hard to see details on moving objects. I have not revisited this in a while, and there has been at least one Avigilon firmware update since. On a side note, when we reported the ghosting issue to Avigilon through our integrator, the recommended "fix" was to disable WDR.

The greatest challenge when the devices are in night mode is that even at faster exposure times, the tail lights, tag lights, and brake lights can "blind" the camera against a detailed image capture.

Have you used the "display adjustments" to adjust the image so the plate is not over exposed? I would say 99% of the time when the plate is over exposed we can ID the plates when adjusting the White Level to 1. Also if you offset the camera from a rear of the plate 10 degrees or so that helps alot.

To help with the night time perfomance you can use the "IR Focus Offset" to adjust the focus when the camera switches to B/W mode. This sets the camera to a new focus point for optional focus under IR light.

Thanks, Michael. We do use the display adjustments, but often the imager just doesn't capture the license info at night because of the overexposure. The domes are more prone to this than the bullets. The available mounting locations often dictate the angle, but we usually see better nighttime results when closer to a straight shot (ymmv).

I was not familiar with the "IR Focus Offset" feature until now. I checked and it appears to be only available via the browser GUI, which I rarely use. I don't see it anywhere in ACC camera settings. I will do some "tinkering" with that setting and see if we can improve our results. Thanks for the info.

. . . and often in ACC 5 just zooming in/out a few steps on the recorded image makes the difference between what appears to be an oversaturated, unusable image and a fully legible plate capture. We also occasionally have good results adjusting the gamma to 1.