Ghost Car LPR

[Frankydp]

So I have a weird anomaly, and I am kinda stumped.

I have this one car that my LPR captures regularly, and only this one car captures with extreme digitization on the image. It is a very beat up Toyota Van. See for yourself I am at a loss as to why only this one car out of dozens is always pixelated.

I am guessing that ALPR is only looking at the change pixels of the camera feed, and something about the sky + the exact color of the previa + the broken up pattern from the body damage equals a kind of camouflage effect?

Still gets the plate just an interesting oddity.

P.S. I know my angle is a little aggressive, I am putting off trenching.

All other vehicles:



Ghost Van:

 

[tangent]

You've got a bit of the same effect on the first car, just a lot less of it. Try turning down your frame rate and noise reduction a bit.

 

[Frankydp]

I am running on 25 3D and 10 on framerate. I will try backing it of slightly.

The network itself is pretty dropy packet wise, with a long range wireless bridge, waiting on a directional to try and clean that up.

 

[tangent]

in that case the network is a likely cause. Maybe someone's running in car wifi lol.

 

[dfhawk]

I would turn off noise reduction, WDR and Gain (at least as a starting point & especially during the day) and turn up frame rate to 20. What are you're other settings i.e. shutter speed?

This hyperlink should also help:

Camera Configuration — openalpr 2.5.103 documentation

 

[Frankydp]

I will try with 3D off, backlight is already off. I do have Contrast and Sharpness at 55. Shutter 1/2000, Gain 10-55, Iris 25.

I have gone through that guide. At my angle the critical setting is shutter speed from what I can tell. Noise correction is a destroyer of plates for certain.

How does that gain setting on the Dahuas translate to DB?(+12)

 

[dfhawk]

I believe it would translate to a 0 to 12 gain - but again I would just do 0 to 0 to start out (again for day settings only) and as your environment dictates it begin to increase it.

 

[Stephen Cable]

Fwiw it's a Chrysler van

 

[richardgohth]

What is your compression type? H.264, high?
What is your bitrate? Constant or Variable?
What is your network max packet size?

When this car first gets into view, when does the pixelation starts?
I guess the front of car will be in view first, at which point does pixelation start.

Run thru your images to see if there are other similar pixelated images? There should be.
For pixelated images see if it is possible to provide the following
1 What is the vehicle color?
2. Are the markings, wordings visible on the side of the car?
3. If the cars come in a "train" ( 2 or more cars together ), is this the first /2nd /3rd car?


Try to change to h.265 if possible
Avoid mjpeg
Change bitrate to as high as possible.

This is due to compression engine trying to squeeze thru a small pipe.

IMHO, not network issues per se.

Network issues results in corrupted images not pixelated ones.

So I have a weird anomaly, and I am kinda stumped.

I have this one car that my LPR captures regularly, and only this one car captures with extreme digitization on the image. It is a very beat up Toyota Van. See for yourself I am at a loss as to why only this one car out of dozens is always pixelated.

I am guessing that ALPR is only looking at the change pixels of the camera feed, and something about the sky + the exact color of the previa + the broken up pattern from the body damage equals a kind of camouflage effect?

Still gets the plate just an interesting oddity.

P.S. I know my angle is a little aggressive, I am putting off trenching.

All other vehicles:
View attachment 27702


Ghost Van:
View attachment 27703

 

[Frankydp]

@richardgohth

So your thought process was right. I was using a low constant bitrate at the time, which provided me the best consistency for video to be viewable.

Pixelation was only happening late in the crossing of the vehicle, which happened to coordinate with the plate being on screen, and when the largest amount of vehicle was in view.

The higher the contrast between the background and the vehicle, the more it pixelated, more change data?

No difference in behavior with trained vehicles.

H.264 for oalpr.

Anyways I did replace my omni antenna with a directional which nearly eliminated packloss on that bridge, and stabilized the entire connection. Was able to walk the bitrate up alot, which in turn gave the feed more pipe to push the high diff data through when the high contrast and larger vehicles rolled by.

Only issue I still have on that zoomed in oblique camera view now is, very inconsistent triggering for both zones and tripwires, even with things vehicle size.

What is your compression type? H.264, high?
What is your bitrate? Constant or Variable?
What is your network max packet size?

Network issues results in corrupted images not pixelated ones.