CCTV effective distance to read a number plate.
chili-girl
a fine sunny day.
Is there a typical distance you can read a number plate.
With one of the SafeCore CCTV 1/3" SONY Colour WDR & ICR(True
Day&Night) Camera (Hi-Res.) cameras 752x582 picture element, 520 lines
resolution, 0.1 Lux / F1.2 day, 0.001 Lux / F1.2 at night
with IR switching and with effective IR illumination.
Lens fitted is a 1/3" 3.5-8mm Vari-Focal Lens, DC drive auto iris
Aperture: F1.4
1 - Is there a typical distance you can read a number plate.
2 - Would I then be able to read a number plape at say 25m.
3 - What would the picture be like at night with IR on, or are they
just too grainy
4 - Or are my problems only due to the PC capture card.
Andy Burns
> For a normal CCTV camera (that is linked to a PC capture card) and on
> a fine sunny day.
>
> Is there a typical distance you can read a number plate.
Depends on the focal length of the lens ...
Assume you need the plate to be approx 10% of the image width to read
the plate (giving approximately eight pixels per character on the plate)
lets round the plate dimensions up to 1.5', so you need a field of view
of 15' to achieve the plate being 10% of the image.
For a 1/3" sensor you'd need a lens of 26mm focal length to give a field
of view of 15' at a distance of 82', unfortunately your 3.5-8mm zoom
lens isn't going to cut it.
Andy Burns
> Is there a typical distance you can read a number plate.
Just to say a bit further ... if you *did* have a 25mm lens to make the
plate readable it wouldn't make a very good CCTV as you'd only see the
car and immediate surroundings, rather than an all round view, which is
why council/police CCTV have pan/tilt/zoom cameras and an operator.
Alan
<usenet....@adslpipe.co.uk> wrote
It may need a lens with a longer focal length (longer than 26mm) as the
camera/lens combination has a resolution lower than a pixel count
suggests.
At night power of the illumination at 25m would have to be adequate and
a ' ring of leds' would probably be insufficient.
The alternative is to get some software such as is used in CSI where you
will be able to read a whole number plate from a single pixel in the
source video.
--
Alan
news2006 {at} amac {dot} f2s {dot} com
Vortex3
>
> 1 - Is there a typical distance you can read a number plate.
> 2 - Would I then be able to read a number plape at say 25m.
> 3 - What would the picture be like at night with IR on, or are they
> just too grainy
> 4 - Or are my problems only due to the PC capture card.
>
Q1 Agreed with Andy above you need at least 8 pixels per character.
Q2 To be pedantic:
* A 1/3" sensor has a size of 4.6 x 3.8mm
* Using an 8mm lens the field of view at 25000mm will be:
* (25000/8) * 4.6 = 14375mm wide
* Sensor has 752 horizontal pixels.
* 14375/752 = > 19mm per pixel. you really need <5mm per pixel.
So answer is "no way". A lens of 25mm or longer will assist.
Q3 Day/Night cameras mechanically remove an internal IR filter for night
operation, hence become sensitive to IR, hence increased gain. Spatial
resolution will be comparable with day
Is the vehicle going to be in motion? If so how fast?
You need to think about the shutter speed, over which you may have no
control. 30mph =~ 13 metres per second so vehicle will move 13cm in 1
millisecond.
Another issue is that of interlacing. This camera will use an interlaced
(so called "interline transfer") sensor. The even lines and odd lines
(called fields) are read out alternately at the rate of 50 fields per
second. The fields are in fact exposed 20 milliseconds apart, with nasty
consequences for resolution.
It is complex but if there is motion the camera will have potentially half
the vertical resolution as horizontal.
++++++++++++++
I'm not sure exactly what you are wanting to achieve (permanent
installation?) but I would be inclined to look for some kind of HDV
camcorder - preferably CCD rather than CMOS - as a starting point.
david
Andrew Gabriel
Alan <junk_...@amac.f2s.com> writes:
>
> It may need a lens with a longer focal length (longer than 26mm) as the
> camera/lens combination has a resolution lower than a pixel count
> suggests.
>
> At night power of the illumination at 25m would have to be adequate and
> a ' ring of leds' would probably be insufficient.
I haven't tried at quite that distance, but at shorter distances,
number plates (and rear reflectors) appear extremely bright
because of the way they reflect light back to the source.
Actually, this can cause the auto-iris to close up such that
the number plates and reflectors are the only items clearly
visible in the field of view at night.
> The alternative is to get some software such as is used in CSI where you
> will be able to read a whole number plate from a single pixel in the
> source video.
;-)
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Andrew Gabriel
"Vortex3" <ne...@nospam.vortex.fsnet.co.uk> writes:
>
> Q3 Day/Night cameras mechanically remove an internal IR filter for night
> operation,
Not any that I've seen.
Actually, I was quite intreagued to discover when I started playing
with them that the switch to IR night vision is not globally across
the whole image, but depends on the lighting level at each part of
the image. A dark part of the image will be in B/W night mode
(subject to there being enough IR lighting), whilst a light part of
the image will be in day colour mode.
> hence become sensitive to IR, hence increased gain. Spatial
> resolution will be comparable with day
>
> Is the vehicle going to be in motion? If so how fast?
>
> You need to think about the shutter speed, over which you may have no
> control. 30mph =~ 13 metres per second so vehicle will move 13cm in 1
> millisecond.
>
> Another issue is that of interlacing. This camera will use an interlaced
> (so called "interline transfer") sensor. The even lines and odd lines
> (called fields) are read out alternately at the rate of 50 fields per
> second. The fields are in fact exposed 20 milliseconds apart, with nasty
> consequences for resolution.
>
> It is complex but if there is motion the camera will have potentially half
> the vertical resolution as horizontal.
and nasty consequences for trying to take a full frame still image
from such a camera. You will end up with two images overlaid on
alternate lines which are 20ms apart. I spent some time with photoshop
once sliding alternate lines to get a good picture of a suspect which
was originally too blurred to recognise, but then became instantly
recognisable to the police.
The Natural Philosopher
>
> The alternative is to get some software such as is used in CSI where you
> will be able to read a whole number plate from a single pixel in the
> source video.
I thought that was spooks and numbers..
Vortex3
news:mngkq4ljocr18vii1...@4ax.com...
> For a normal CCTV camera (that is linked to a PC capture card) and on
> a fine sunny day.
>
> Is there a typical distance you can read a number plate.
>
> With one of the SafeCore CCTV 1/3" SONY Colour WDR & ICR(True
> Day&Night) Camera (Hi-Res.) cameras 752x582 picture element, 520 lines
> resolution, 0.1 Lux / F1.2 day, 0.001 Lux / F1.2 at night
> with IR switching and with effective IR illumination.
>
Do you own one of these cameras, or were you just thinking of buying one?
You see coincidentally I was just about to list a camera on eBay that might
be interesting to you....(accept my apologies for being presumptuous)
Text:
http://home.btconnect.com/vortex/mcl/MCL1500eBaytext.pdf
Datasheet: http://home.btconnect.com/vortex/mcl/MCL1500.pdf
Manual: http://home.btconnect.com/vortex/mcl/MCL1500Manual.pdf
BTW This camera is a good bit of kit but DOESN'T have a night mode.
Ping me if interested. I was hoping to convert it into enough money to buy
a takeaway. That's all!
D
Andy Burns
> I spent some time with photoshop
> once sliding alternate lines to get a good picture of a suspect which
> was originally too blurred to recognise, but then became instantly
> recognisable to the police.
Doesn't it have a filter for de-interlacing? GIMP does ...
nightjar
At the entrance to our industrial estate there are five CCTV cameras, set up
by a security company. Two colour cameras give short range pictures of the
gate, in opposite directions. Two colour cameras give long views of vehicles
approaching the gates. One high definition monochrome camera captures the
number plates of vehicles entering the estate - you don't need colour for
number plates and monochrome is capable of both higher definition and lower
light response. It is set about3m high and looks down at about 30 degrees.
Steel bollards guide the vehicles through the gateway, ensuring that the
number plates are in the field of view. At night, the area is lit by 2 x
150W high pressure sodium street lamps, as one did not provide enough light.
Colin Bignell
Andrew Gabriel
Oh, it might do now. This was some years back, Photoshop 4 or 5 era.
Photoshop 5 is the last version I bought.
Matty F
> 1 - Is there a typical distance you can read a number plate.
> 2 - Would I then be able to read a number plape at say 25m.
> 3 - What would the picture be like at night with IR on, or are they
> just too grainy
> 4 - Or are my problems only due to the PC capture card.
During the day you may get to read a number plate if the vehicle is
moving slowly and it's only a few metres away or you have a very good
telephoto which you can point straight at the front or rear of the
vehicle.. With all the CCTV cameras I've used, about one third of the
plate is blurred over the rest, making it unreadable. At night I once
managed to read a plate, only because the car was almost stopped about
5 metres away.
What I'd like is an infrared flash that flashes 25 times per second
all night, but I've not found one yet. I may try to make one using a
spinning wheel and some infrared LEDs. If the plates are reflective a
few LEDs will reach 6 metres or so.
Look up "trail camera". There are some with an infrared flash that
take a photo when movement is detected.
Otherwise an ordinary digital camera focussed to infinity will take
excellent flash photos up to 50 metres away for a moving vehicle. If
the vehicle is not moving, a three second exposure focussed to
infinity using a tripod will get plate numbers at night without using
the flash.
Dave Plowman (News)
Alan <junk_...@amac.f2s.com> wrote:
> The alternative is to get some software such as is used in CSI where you
> will be able to read a whole number plate from a single pixel in the
> source video.
Yup. Very clever that. Now all they need is the software to sort out the
appalling direction on last night's episode of 'New York'.
--
*Why do we say something is out of whack? What is a whack? *
Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.
Owain
> I'm not sure exactly what you are wanting to achieve (permanent
> installation?) but I would be inclined to look for some kind of HDV
> camcorder - preferably CCD rather than CMOS - as a starting point.
Megapixel IP CCTV camera is probably what is needed. Much more
controllable, with the camera able to do its own motion detection and
record different resolutions at different times.
http://www.networkwebcams.co.uk/index.php?cPath=99
There's a quiet, but fairly responsive, forum on the site as well
Owain
Vortex3
news:_radnfMEjJ-mTTfU...@posted.plusnet...
The issue with IP cameras is the compression they use.
The danger is that all the high fequency data is trashed, and therefore the
plate in this instance would be illegible anyhow.
D
Clint Sharp
<and...@cucumber.demon.co.uk> writes
>In article <70v41rF...@mid.individual.net>,
> "Vortex3" <ne...@nospam.vortex.fsnet.co.uk> writes:
>>
>> Q3 Day/Night cameras mechanically remove an internal IR filter for night
>> operation,
>
>Not any that I've seen.
exactly this and they can give excellent results for reasonable prices.
They've been around for five or six years that I know of and possibly
longer.
--
Clint Sharp
tony sayer
<owain...@stirlingcity.coo.uk> scribeth thus
They seem a tad expensive for doing it over IP?...
--
Tony Sayer
Mark
Have you considered the legal or ethical implications of this? I know
the "Big Brother" philosophy seems to have spread everywhere now and
spying is acceptable. But, I for one, don't agree.
Forgive me if I have got the wrong end of the stick here.
--
(\__/) M.
(='.'=) Owing to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking most articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.
See http://improve-usenet.org
Matty F
> Have you considered the legal or ethical implications of this? I know
> the "Big Brother" philosophy seems to have spread everywhere now and
> spying is acceptable. But, I for one, don't agree.
>
> Forgive me if I have got the wrong end of the stick here.
Catching crooks is a good way of slowing them down from committing
more crime.
> --
> (\__/) M.
> (='.'=) Owing to the amount of spam posted via googlegroups and
> (")_(") their inaction to the problem. I am blocking most articles
> posted from there. If you wish your postings to be seen by
> everyone you will need use a different method of posting.
> Seehttp://improve-usenet.org
You won't be seeing this then.
The Natural Philosopher
> On Mar 3, 10:18 pm, Mark <i...@dontgetlotsofspamanymore.net> wrote:
>
>> Have you considered the legal or ethical implications of this? I know
>> the "Big Brother" philosophy seems to have spread everywhere now and
>> spying is acceptable. But, I for one, don't agree.
>>
>> Forgive me if I have got the wrong end of the stick here.
>
> Catching crooks is a good way of slowing them down from committing
> more crime.
>
crimes they wont so easily get caught for..
charles turner
distance,
http://networkvideosystems.co.uk/epages/eshop145782.sf/en_GB/?
ObjectPath=/Shops/eshop145782/Categories/%22Sony%20IPELA%22
http://networkvideosystems.co.uk
Thanks
Owain
wrote:
> I belive the Saony IP range to be very good at reading number plates from
> distance,
I believe you're spamming this newsgroup, Mr Turner.
Owain
Andy Champ
>
> I believe you're spamming this newsgroup, Mr Turner.
>
Do you think he means to spam about Sony or Sanyo?
Andy
Spamlet
"Owain" <spuorg...@gowanhill.com> wrote in message
news:c07ae24e-cb05-4534...@n3g2000yqb.googlegroups.com...
Owain
If not spam, take note of recent QI prog where they said motorcycle was best
for speed cameras as they only read *front* number plates. Which may or may
not actually be true...
S
Owain
> Do you think he means to spam about Sony or Sanyo?
Maybe he's been spending so long looking at cctv his eyes have gone
funny.
Owain
dennis@home
"Spamlet" <spam.m...@invalid.invalid> wrote in message
news:i80bb3$66l$1...@news.eternal-september.org...
Gatsos can only read rear plates so I guess there is your answer (actually
the camera doesn't care but the safety police only let them do rears).
ARWadsworth
So what. Just do a wheelie when you go past a Gatso on a motorbike.
--
Adam
dennis@home
"ARWadsworth" <adamwa...@blueyonder.co.uk> wrote in message
news:0EOoo.7122$Wp7...@newsfe24.ams2...
> So what. Just do a wheelie when you go past a Gatso on a motorbike.
What's that got to do with cameras only reading front plates?
Spamlet
"dennis@home" <den...@killspam.kicks-ass.net> wrote in message
news:i80dbp$tf1$1...@news.datemas.de...
Actually, thinking again, to be fair, they were talking about why
motorcycles are exempt from London's congestion charge, rather than Gatso's:
I don't know if the monitors for the congestion charge work the same way.
S
ARWadsworth
Gatso's read rear number plates...........
--
Adam
dennis@home
"Spamlet" <spam.m...@invalid.invalid> wrote in message
news:i80jlr$7bs$1...@news.eternal-september.org...
The same reason lpg and electric cars are exempt, they "don't" cause
congestion. 8-|
Andy Burns
> Gatsos can only read rear plates so I guess there is your answer
> (actually the camera doesn't care but the safety police only let them do
> rears).
Truvelos (sp?) only do fronts, don't they?
Spamlet
motorcyclist Ross Noble knew the 'correct' answer: that they don't have
front number plates (mind you, I still have a couple somewhere!)
S