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.

Lens fitted is a 1/3" 3.5-8mm Vari-Focal Lens, DC drive auto iris
Apertu 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.

chili-girl wrote:

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.

chili-girl wrote:

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.

In message , Andy Burns
wrote
chili-girl wrote:

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.


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

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

In article ,
Alan 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]

In article ,
"Vortex3" 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.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Alan 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.

I thought that was spooks and numbers..

"chili-girl" wrote in message
...
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...00eBaytext.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

Andrew Gabriel wrote:

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 ...

"chili-girl" wrote in message
...
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.

Lens fitted is a 1/3" 3.5-8mm Vari-Focal Lens, DC drive auto iris
Apertu 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.

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

In article ,
Andy Burns writes:
Andrew Gabriel wrote:

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 ...

Oh, it might do now. This was some years back, Photoshop 4 or 5 era.
Photoshop 5 is the last version I bought.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Mar 1, 9:24 pm, chili-girl wrote:

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.

In article ,
Alan 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 London SW
To e-mail, change noise into sound.

In message , Andrew Gabriel
writes
In article ,
"Vortex3" writes:

Q3 Day/Night cameras mechanically remove an internal IR filter for night
operation,

Not any that I've seen.
Got one on the desk in front of me. There are plenty out there that do
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

"Owain" wrote in message
...
Vortex3 wrote:
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



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

In article , Owain
scribeth thus
Vortex3 wrote:
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


They seem a tad expensive for doing it over IP?...
--
Tony Sayer

On Sun, 1 Mar 2009 11:31:03 -0000, "nightjar" cpb@insert my surname
here.me.uk wrote:


"chili-girl" wrote in message
.. .
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.

Lens fitted is a 1/3" 3.5-8mm Vari-Focal Lens, DC drive auto iris
Apertu 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.

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.

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

On Mar 3, 10:18 pm, Mark 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.

--
(\__/) 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.

Matty F wrote:
On Mar 3, 10:18 pm, Mark 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.

And a better way of educating them in the HM prison system, to commit
crimes they wont so easily get caught for..

On 28/09/2010 23:44, Owain wrote:

I believe you're spamming this newsgroup, Mr Turner.



Do you think he means to spam about Sony or Sanyo?

Andy

"Owain" wrote in message
...
On Sep 28, 7:10 pm, "charles
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


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

"Spamlet" wrote in message
...

"Owain" wrote in message
...
On Sep 28, 7:10 pm, "charles
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


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...

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).

dennis@home wrote:
"Spamlet" wrote in message
...

"Owain" wrote in message
...
On Sep 28, 7:10 pm, "charles
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


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...

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).


So what. Just do a wheelie when you go past a Gatso on a motorbike.


--
Adam

"ARWadsworth" wrote in message
...


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?

"dennis@home" wrote in message
...


"ARWadsworth" wrote in message
...


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?

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

dennis@home wrote:
"ARWadsworth" wrote in message
...


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?

Gatso's read rear number plates...........



--
Adam

"Spamlet" wrote in message
...

"dennis@home" wrote in message
...


"ARWadsworth" wrote in message
...


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?

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.

The same reason lpg and electric cars are exempt, they "don't" cause
congestion. 8-|

dennis@home wrote:

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?

"dennis@home" wrote in message
...


"Spamlet" wrote in message
...

"dennis@home" wrote in message
...


"ARWadsworth" wrote in message
...


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?

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.

The same reason lpg and electric cars are exempt, they "don't" cause
congestion. 8-|
No: that is the reply the 'QI elves' had set up as the booby trap: only
motorcyclist Ross Noble knew the 'correct' answer: that they don't have
front number plates (mind you, I still have a couple somewhere!)

S