help configuring ltc0495 for catching licence plate

[lemike 0]

hello,

first of all, i'm sorry for my poor english

i need some help to correctly configure a bosch ltc0495 to catch licence plates, here is a capture :

the picture is saturated and the plate isn't correctly identifiable

i was previously using a ltc 0455 and the capture were better:

 

as there are too many parameters in this camera i'm totaly lost and your help would be really appreciated

i'd like to know if i should force the camera in colorr mode & what would be the best parameters for alc, sens up, gain, xf dinion...

thanks in advance

[jisaac 0]

have not had any experience with that particular camera. But what I do know is that I have had the best experience having cameras for license plate recognition when I have them closer to the ground almost looking straight ahead at the plates.

[Securitymaster 0]

Are you using the same lens as the older camera?

[lemike 0]

i can't place it closer to the ground, actually the camera is 40meters far from the enter and apprx 8meters high (so i can't climb every 5 minutes to make tests...) & i'm using a 5-50mm lens (same as the older camera), i had tried with 2.5meters hight but some burglars broke it and the results were not good, as i'm a ski resort, i can't place it under the vehicule due to the snow

 

some other things that i didn't mention:

 

i'm using an halogen spot to highlight the plates when cars are enterring the parking,

 

i have a short laptime to catch a clear picture (there is approx 4seconds between the entering point and the exit of the field of view, i have between 1 and 2 seconds before the car speedsup), i used to have a lot of motion blur with the old camera, i don't know if i should set the shutter to AES, Flikerless or to maintain it fixed at a certain speed, i made a test with a fixed shutter (1/250), it seems to avoid motion blur but the picture still really awfull...

for curious ones, here is a link to the camera manual:

http://www.burlecctv.com/pdf/LTC0495.pdf

[rory 0]

it looks pretty good actually, only issue i can see is like the others mentioned, height, where you will have an issue with lighting up the licence plate.

 

If it was the same location, is the lens the same exact one? What F:stop is the lens?

 

The slower the Shutter speed the more light the camera lets in .. so if you slow it down, you will see more, in for example image 1, in theory. I would try Auto first, then test it at lower settings only if it doesnt work in that mode. here is some futher info:

http://www.cctv-information.co.uk/constant3/anpr.html

 

Was the 1/250 setting bad as in still dark?

 

Proper licence plate capture you want to get as low to the ground as possible, as low as 4 foot for example .. but like you said you will have other issues at that height.

 

Rory

[lemike 0]

kindly note that the first picture concern my actual setting, the other were toke with my old configuration and are really better...

concerning the lens it is same one, (1/3 5~50mm F/1.6 Aspherical Vari-Focal), with 1/250 i have a quite dark picture, the subject isn't blurred but as you can see the plate isn't recognizable...

[rory 0]

weird, f:1.6 is not that low lux, F:1.3 would be a better lens to use in that area, such as the Computar 5-50mm f:1.3 or the Fujinon 5-50mm f:1.3. (i say that cause i just used a Computar 5-50mm lens)

 

The old camera might have had the iris pot open more, SAGC or something else .. do you have the old camera so you can check its settings if it had dip switches?

 

I really dont know that camera, but check the night vision thing it has, make sure that is turned on as bright as possible.

 

You want to force the camera into BW mode though for low light, and focus it in low light (while in BW mode) just before it gets dark.

 

In a case i just had, i switched a camera into a new housing and had all kinds of issues, I had to change the lens, then it was much better, but still not the same as before as was a differnt lens, My case, it was a bad lens, in your case maybe just a different camera and lens capability, eg. f:1.6 on the new camera. Wide Dynamic cameras normally wont be as low lux though so that may be the issue, maybe not. It sais it is 0.2 lux (i always ignore the extra 0) so i would force it into BW mode in low light or night time, and see what you get, even if you need to use a photocell to do so. If you have the manual, if like to see it It sais "sens" up is 0.02 lux though, have you tried that yet? I had issues with cameras switching to color at night time, when in reality it should stay in BW, i have to look for a photo cell myself. Basically color in the day, BW and night ... Im using IR so i had extra issues also .. the old lens from a different manufacturer worked much better under IR than the new one .. but the new one was much better for just Day Night Ops and also was a longer Zoom. Im having to buy a new IR lens for it now, but thats a whole other issue.

 

Anyway, it looks like its focused, but try to make it stay in BW mode in low light and see what you get, BW will see much more.

 

Thanks

Rory

[lemike 0]

thanks for your help rory, i really appreciate

the old camera was setted like this:

agc on

shutter off

(no more parameters)

may i made a bad back focus adjustment? is there someone that could explain me hw to do this correctly?

i'll made a new test tonight with the shutter @ 1/100 and auto Day/night mode, if it still unconcluant i'll try to change the lens

[rory 0]

Focus doesnt seem to be a problem, everything looks in focus, its more than likely light related. Try some more tests then let us know what you get. You want to force it into BW mode if you can, for night, as thats the best quality at night.

 

Thanks

Rory

[lemike 0]

i'll let you know, do you know where i could order this 5-50mm lens online?

is there other specific low lux lens?

[rory 0]

this is the lens, the middle one.

http://www.cbcamerica.com/cctvprod/computar/vari/0550.html

[rory 0]

not in a telephoto lens .. Fujinon has a f:0.95 lens but its like 3-8mm.

http://www.fujinoncctv.com/pdfs/cctv0904/YV27x29LA-2.pdf

 

I'd work on the camera first though .. how does the daytime image with sunlight compare to the old camera?

 

Rory

[lemike 0]

daytime picture are as good as before

[rory 0]

typically you should leave AGC off if used outdoors, due to the sun light glare. does this new camera have the AGC on or off by default or did you turn it on? I think it has an OSD right?

 

Basically slow shutter, AGC, BLC, and wider IRIS pot level, makes it brighter.

For night time BW mode "should" be much brighter also, and also should have a mechanical switchover, but i dont know this camera so cant say for sure.

 

rory

[lemike 0]

agc can be selected, if i put it off, the picture is totally dark,

i've setted this paramter to auto agc, max 20db

[rory 0]

also try the sensitivety "up" mode, what i read in the data sheet, makes it brighter. have you got it to go into BW mode as yet? (7am im off to bed now)

 

Rory

[lemike 0]

i tried sens up but the image is blurred

anyway let's see the result of tonight test,

have a good rest rory & thx again for your help

[lemike 0]

well i guess i'll stop on this result:

settings are:

shutter: fixed @ 1/100 (got motion blur under)

agc fixed @ +15db (too dark under, too much noise above)

sensup off

blc off

alc +15

alc peak/average +15

color mode forced (better result)

autoblack on (+5) (better result, especially when it's snowing)

contour + 5 (increase the sharpness)

dnr off

xf dyn mid

 

well finally i would not recommand this camera.... the ltc 0455 gave nearly the same results for half the price

[lemike 0]

But, for low light wide surveillance the ltc0495 is good!

this was with the 0455:

and this is with the 0495:

[rory 0]

Oh well, tis why i use Extreme Reg cameras for licence plate apps ..

[lemike 0]

well this kind of camera is quite expensive and i'm not sure that it could work at long distances like in my configuration

i got a new shot, i guess it's the best one, the halogen spot didn't work due to the snow and the plate still identifiable

[Cooperman 0]

My initial impressions are that the imaging problem appears to be more to do with lighting than anything else (unless bosch cameras prefer BMW's to Peugeots )

 

Where a vehicle has it's fog lights on, they're throwing light straight down to the ground, and the reflectance off the snow is lighting the front of the vehicle and number plate, thereby offsetting the iris closing effect caused by intense headlights.

 

The rear view looks even better exposed, again because there are no intense headlights causing the iris to over compensate.

 

Ideally, if the cameras fixed shutter can be used at 1/250th to reduce movement blur, and the ambient light increased onto the target area (visible light for colour operation, infra red only if the camera is photocell switched into B/W at night), then you should get a very reasonable result.

 

Using a floodlight at that distance is not really going to be much use, as the lighting ratio between the highlights (the vehicle headlights) and the shadow areas will be outside the range of the imager. In other words, there just isn't enough light output from your flood, to offset the negative effect of headlights. Perhaps as an experiment try using either a much narrower beam light source(s), or take the flood much nearer to the target area (perhaps 10 metres away).

 

Applying the "sens up" will not help, as frame integration will certainly increase sensitivity but at the expense of increasing the blur effect as the vehicle moves through the image.

 

Incidentally, raising the height of the camera (although less than ideal from an operational point of view) does help to reduce the negative effects of vehicle lights.

 

As far as I am aware, the ANPR cameras used for the London Congestion Charge scheme, are all mounted well off the ground, and optimised for plate recognition at perhaps 20 - 30 metres from the pole.

[lemike 0]

yes i know that i have a big light problem, i don't want to use an ir light 'cause it's too expensive, i'd like to change my halogene spot which have a wide and not really powerfull beam with a narrow powerful light, i don't know exactly what to use

[lemike 0]

after some months trying to achieve the best capture, i finally bought an uf300 and here is the result:

the plate is perfectly identifiable even when it's raining or snowing

the ltc0495 have a special Ir contrats function wich filter normal lighting, well i guess i'm close to the REG result

settings:

shutter: fixed @ 1/100

agc fixed @ 0db

sensup off

blc off

alc 0

alc peak/average +15

autoblack on (-20)

contour + 5

dnr off

xf dyn off

ir contrat echanced

[rory 0]

thats brilliant man ... save some money without having to buy the Reg ... UF300 ..? Is that like the UF100 or UF500?? What IR beam and Lens was used and distances from camera and IR to car location?

 

Also, hows the day image?

 

thanks

Rory