nightjar cpb@ wrote:

Or whatever technology they use for average speed cameras. they are about
the only cameras I can think of that read number plates without slowing the
vehicles down first.

Colin Bignell

How are you feeling Colin?

Have you had the opp, or is that to come yet?

Nice to see you posting in various news groups though.

Dave

On Mon, 7 Sep 2009 20:54:20 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:


"Matty F" wrote in message
...
On Sep 7, 2:24 am, "nightjar" cpb@insert my surname here.me.uk
wrote:
"Matty F" wrote in message

Other problems are that the cars are usually moving at speed, and the
rego number is therefore blurred. The headlights and tail-lights are
also too bright and wash out the picture.
What I need is an invisible LED strobe that runs all night. I can't
find any so I suppose I'll have to make it.

Professional systems use IR floodlights.

A continuous light is not good enough because the number plate is
blurred when the car is moving at speed.
I need a flash, like this taken on my digital camera:
http://i30.tinypic.com/13zmid1.jpg

The lower car is moving at about 60 miles an hour and its number plate
is perfectly readable.

But I want a non-visible flash, i.e. infrared. And it needs to flash
about 10 times per second all night, every night.
Or I need a video camera with a shutter speed of a thousandth of a
second.

Or whatever technology they use for average speed cameras. they are about
the only cameras I can think of that read number plates without slowing the
vehicles down first.

At night? During daylight I assume they have a long focus lens to take
the pic at sufficient distance that the distance travelled during
exposure divided by total distance is a small enough fraction not to
cause blurring. But thats ust a guess.

Phil

"Phil Addison" wrote in message
...
On Mon, 7 Sep 2009 20:54:20 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:
.....
Or whatever technology they use for average speed cameras. they are about
the only cameras I can think of that read number plates without slowing
the
vehicles down first.

At night?

I would think that is when speeding is more likely to happen.

During daylight I assume they have a long focus lens to take
the pic at sufficient distance that the distance travelled during
exposure divided by total distance is a small enough fraction not to
cause blurring. But thats ust a guess.

Colin Bignell

"Dave" wrote in message
...
nightjar cpb@ wrote:

Or whatever technology they use for average speed cameras. they are about
the only cameras I can think of that read number plates without slowing
the vehicles down first.

Colin Bignell

How are you feeling Colin?

I feel fine, thank you. In fact, apart from the event in February, which put
me in hospital and lasted only a couple of hours, I've not felt ill at all.

Have you had the opp, or is that to come yet?

Soon, I hope. I've just posted an update.

Colin

On Tue, 8 Sep 2009 16:49:38 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:


"Phil Addison" wrote in message
...
On Mon, 7 Sep 2009 20:54:20 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:
....
Or whatever technology they use for average speed cameras. they are about
the only cameras I can think of that read number plates without slowing
the
vehicles down first.

At night?

I would think that is when speeding is more likely to happen.

Not sure about that, but do you reckon they work in darkness?

During daylight I assume they have a long focus lens to take
the pic at sufficient distance that the distance travelled during
exposure divided by total distance is a small enough fraction not to
cause blurring. But thats ust a guess.

If this theory is correct its hard to see how they can sufficiently
illuminate a number plate at a distance without a ginormous flash for
every car that passes.

Phil

On Tue, 08 Sep 2009 18:41:20 +0100, Phil Addison wrote:

On Tue, 8 Sep 2009 16:49:38 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:


"Phil Addison" wrote in message
...
On Mon, 7 Sep 2009 20:54:20 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:
....
Or whatever technology they use for average speed cameras. they are about
the only cameras I can think of that read number plates without slowing
the
vehicles down first.

At night?

I would think that is when speeding is more likely to happen.

Not sure about that, but do you reckon they work in darkness?

During daylight I assume they have a long focus lens to take
the pic at sufficient distance that the distance travelled during
exposure divided by total distance is a small enough fraction not to
cause blurring. But thats ust a guess.

If this theory is correct its hard to see how they can sufficiently
illuminate a number plate at a distance without a ginormous flash for
every car that passes.

Phil

All the Specs (average speed) cameras that I have seen have a pair of what
I presume are infra-red lights with the camera in the middle. I think they
are simply infra-red video cameras feeding a computer recognition and
recording system. With sufficient lighting, the equivalent of shutter speed
should be able to be quite high to minimise blurring.

SteveW

On Mon, 07 Sep 2009 11:21:21 +0100, Rob Horton wrote:

Matty F wrote:
After publicity about a number of vandals and taggers caught because
of hidden CCTV cameras that I have installed in the neighbourhood, I
decided to put up a rather obvious CCTV camera (fake) complete with
flashing red light.
Someone recently went to a lot of trouble to pinch the fake camera.
The theft and their car was recorded on three of the real cameras. Not
quite good enough to identify them but I'm working on a new camera
that should capture rego numbers.
I don't want them to pinch or damage the real cameras.

I'd like to put up another fake camera. Does anyone have bright ideas
on something amusing to put on the camera to give them a big fright
when they try to pinch it? A loud alarm perhaps. Some compound that
gets on their hands and can't be washed off for weeks? etc etc?

Some how coat the outside with hydrofluoric acid?

From the Haynes manual:

"Special hazards
Hydrofluoric acid
l This extremely corrosive acid is formed when certain types of
synthetic rubber, found in some O-rings, oil seals, fuel hoses etc, are
exposed to temperatures above 400°C. The rubber changes into a charred
or sticky substance containing the acid.

Viton seals.

Once formed, the acid remains
dangerous for years. If it gets onto the skin, it may be necessary to
amputate the limb concerned"

This is not a serious suggestion.

If it was, we could just cut out the middle man and fit a swinging chainsaw
activated by removal of the camera!

SteveW

nightjar cpb@ wrote:
"Dave" wrote in message
...
nightjar cpb@ wrote:

Or whatever technology they use for average speed cameras. they are about
the only cameras I can think of that read number plates without slowing
the vehicles down first.

Colin Bignell
How are you feeling Colin?

I feel fine, thank you. In fact, apart from the event in February, which put
me in hospital and lasted only a couple of hours, I've not felt ill at all.

Have you had the opp, or is that to come yet?

Soon, I hope. I've just posted an update.

Yes, I've just read it. Looks like you have a better medical team around
you now.

Once again, I won't wish you well, but I will look forward to your
future posts and plenty of them.

Dave

On Sep 9, 7:48 am, Steve Walker wrote:
On Mon, 07 Sep 2009 11:21:21 +0100, Rob Horton wrote:
Matty F wrote:
After publicity about a number of vandals and taggers caught because
of hidden CCTV cameras that I have installed in the neighbourhood, I
decided to put up a rather obvious CCTV camera (fake) complete with
flashing red light.
Someone recently went to a lot of trouble to pinch the fake camera.
The theft and their car was recorded on three of the real cameras. Not
quite good enough to identify them but I'm working on a new camera
that should capture rego numbers.
I don't want them to pinch or damage the real cameras.

I'd like to put up another fake camera. Does anyone have bright ideas
on something amusing to put on the camera to give them a big fright
when they try to pinch it? A loud alarm perhaps. Some compound that
gets on their hands and can't be washed off for weeks? etc etc?

Some how coat the outside with hydrofluoric acid?

From the Haynes manual:

"Special hazards
Hydrofluoric acid
l This extremely corrosive acid is formed when certain types of
synthetic rubber, found in some O-rings, oil seals, fuel hoses etc, are
exposed to temperatures above 400°C. The rubber changes into a charred
or sticky substance containing the acid.

Viton seals.

Once formed, the acid remains
dangerous for years. If it gets onto the skin, it may be necessary to
amputate the limb concerned"

This is not a serious suggestion.

If it was, we could just cut out the middle man and fit a swinging chainsaw
activated by removal of the camera!

I don't think I want to injure anyone, as they may retaliate.
I've made a very strong fake camera out of 75mm steel pipe fixed on
the pole with a 20mm steel bolt. It should be immune to even a
sledgehammer. I could even put a camera in it to video a contorted
face getting very close.

In uk.d-i-y, Matty F wrote:
I don't think I want to injure anyone, as they may retaliate.
I've made a very strong fake camera out of 75mm steel pipe fixed on
the pole with a 20mm steel bolt. It should be immune to even a
sledgehammer. I could even put a camera in it to video a contorted
face getting very close.

Hey, a fake camera with a camera in it! Brilliant!

--
Mike Barnes

"Steve Walker" wrote in message
...
On Tue, 08 Sep 2009 18:41:20 +0100, Phil Addison wrote:

On Tue, 8 Sep 2009 16:49:38 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:


"Phil Addison" wrote in message
...
On Mon, 7 Sep 2009 20:54:20 +0100, "nightjar" cpb@insert my surname
here.me.uk wrote:
....
Or whatever technology they use for average speed cameras. they are
about
the only cameras I can think of that read number plates without
slowing
the
vehicles down first.

At night?

I would think that is when speeding is more likely to happen.

Not sure about that, but do you reckon they work in darkness?

I don't think they would be much use if they did not. However, as I only see
them in road works, where there is a speed restriction, I wonder whether
there is a maximum speeed at which they are effective.


During daylight I assume they have a long focus lens to take
the pic at sufficient distance that the distance travelled during
exposure divided by total distance is a small enough fraction not to
cause blurring. But thats ust a guess.

If this theory is correct its hard to see how they can sufficiently
illuminate a number plate at a distance without a ginormous flash for
every car that passes.

Phil

All the Specs (average speed) cameras that I have seen have a pair of what
I presume are infra-red lights with the camera in the middle. I think they
are simply infra-red video cameras feeding a computer recognition and
recording system. With sufficient lighting, the equivalent of shutter
speed
should be able to be quite high to minimise blurring.

The ones I saw yesterday were just like that, some of them at quite oblique
angles to the traffic. I wonder whether it is important that they get a
picture that would be legible to the human eye or whether it is all down to
clever software.

Colin Bignell

nightjar cpb@ wrote:
The ones I saw yesterday were just like that, some of them at quite oblique
angles to the traffic. I wonder whether it is important that they get a
picture that would be legible to the human eye or whether it is all down to
clever software.

As far as I know we're still some way from having software that's as
good as the human eye/brain, let alone better. If a person can't read
the plate a computer isn't going to be able to.

Pete

Pete Verdon wrote:
nightjar cpb@ wrote:
The ones I saw yesterday were just like that, some of them at quite
oblique angles to the traffic. I wonder whether it is important that
they get a picture that would be legible to the human eye or whether
it is all down to clever software.

As far as I know we're still some way from having software that's as
good as the human eye/brain, let alone better. If a person can't read
the plate a computer isn't going to be able to.


You're forgetting the time constraint. ANPR equipment can snap an
oncoming vehicle, identify and zoom into the number plate area, and then
read it and be onto the next vehicle, all before you or I have had time
to say "Uh?"

ANPR isn't completely reliable, but there's an uncomfortably high
correlation between readings at independent sites when they are being
used for calculating average speeds.



--
Ian White

Ian White wrote:
Pete Verdon wrote:
nightjar cpb@ wrote:

The ones I saw yesterday were just like that, some of them at quite
oblique angles to the traffic. I wonder whether it is important that
they get a picture that would be legible to the human eye or whether
it is all down to clever software.

As far as I know we're still some way from having software that's as
good as the human eye/brain, let alone better. If a person can't read
the plate a computer isn't going to be able to.

You're forgetting the time constraint. ANPR equipment can snap an
oncoming vehicle, identify and zoom into the number plate area, and then
read it and be onto the next vehicle, all before you or I have had time
to say "Uh?"

Not forgetting the time aspect - ignoring it as irrelevant to the
question. Colin wondered whether the software was able to analyse images
taken at such an adverse angle that a human would be unable to read the
plate; I was giving my opinion that it was not. Time doesn't come into that.

Clearly where time (really, throughput) is an issue, the computer wins
as you say.

Pete

On Sep 6, 2:27*pm, "Fredxx" wrote:
"Graeme" wrote in message

news
In message , Mike Harrison
writes
On Sun, 6 Sep 2009 01:06:29 -0700 (PDT), Matty F
wrote:

I'd like to put up another fake camera. Does anyone have bright ideas
on something amusing to put on the camera to give them a big fright
when they try to pinch it? A loud alarm perhaps. Some compound that
gets on their hands and can't be washed off for weeks? etc etc?

Filll with indelible skin-dying ink which spills out of holes in the side
when it's moved.

A bottle of black Quink? *Cheap and cheerful.

The trouble with paints and inks is that the solvent is designed to
evaporate. *What the OP needs to do is replace or add a solvent which by
nature is fluid but stable and non volatile. *Perhaps a heavy fractionate of
oil with some serious quantity of staining pigment. *A open tin or bottle
would do the trick once it's moved and has toppled within the camera
housing. *And then slowly oozes out of the housing?

engine oil plus diesel should be just about spot on. Used engine oil
for extra points. Mix in some standard household gloss for the
pigment, but that will settle.


NT

On Sep 10, 7:33 am, Pete Verdon
d wrote:
Ian White wrote:
Pete Verdon wrote:
nightjar cpb@ wrote:
The ones I saw yesterday were just like that, some of them at quite
oblique angles to the traffic. I wonder whether it is important that
they get a picture that would be legible to the human eye or whether
it is all down to clever software.
As far as I know we're still some way from having software that's as
good as the human eye/brain, let alone better. If a person can't read
the plate a computer isn't going to be able to.
You're forgetting the time constraint. ANPR equipment can snap an
oncoming vehicle, identify and zoom into the number plate area, and then
read it and be onto the next vehicle, all before you or I have had time
to say "Uh?"

Not forgetting the time aspect - ignoring it as irrelevant to the
question. Colin wondered whether the software was able to analyse images
taken at such an adverse angle that a human would be unable to read the
plate; I was giving my opinion that it was not. Time doesn't come into that.

Clearly where time (really, throughput) is an issue, the computer wins
as you say.

Enforcement authorities have the advantage of having the money to buy
the equipment needed, and in some cases can position cameras in a good
place to get good pictures.
I'd like to attach my cameras to power poles or over the middle of the
road, but I'm not allowed to!
I'm happy to slowly enhance my video pictures until I can read the
rego plate. On one occasion I resized 8 pictures of a moving car and
averaged them together in order to read the plate successfully.

"NT" wrote in message
...
On Sep 6, 2:27 pm, "Fredxx" wrote:
"Graeme" wrote in message

news
In message , Mike Harrison
writes
On Sun, 6 Sep 2009 01:06:29 -0700 (PDT), Matty F

wrote:

I'd like to put up another fake camera. Does anyone have bright ideas
on something amusing to put on the camera to give them a big fright
when they try to pinch it? A loud alarm perhaps. Some compound that
gets on their hands and can't be washed off for weeks? etc etc?

Filll with indelible skin-dying ink which spills out of holes in the
side
when it's moved.

A bottle of black Quink? Cheap and cheerful.

The trouble with paints and inks is that the solvent is designed to
evaporate. What the OP needs to do is replace or add a solvent which by
nature is fluid but stable and non volatile. Perhaps a heavy fractionate
of
oil with some serious quantity of staining pigment. A open tin or bottle
would do the trick once it's moved and has toppled within the camera
housing. And then slowly oozes out of the housing?

engine oil plus diesel should be just about spot on. Used engine oil
for extra points. Mix in some standard household gloss for the
pigment, but that will settle.


NT

I would say used diesel engine oil would be pretty good!!