I have lots of cameras in my current design (solve problem once, apply
many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
One approach is to drive the entire "illuminator" with different
current levels to get varying intensity output.
Another approach is to drive varying *numbers* of emitters
(at fixed drive levels).
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
mandag den 11. september 2023 kl. 23.50.46 UTC+2 skrev Don Y:
I have lots of cameras in my current design (solve problem once, apply
many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
One approach is to drive the entire "illuminator" with different
current levels to get varying intensity output.
Another approach is to drive varying *numbers* of emitters
(at fixed drive levels).
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
if you are trying to save power you'll need a switching regulator so it is trivial to control the output level and controlling the level instead of number won't change the light pattern
I have lots of cameras in my current design (solve problem once, apply
many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
One approach is to drive the entire "illuminator" with different
current levels to get varying intensity output.
Another approach is to drive varying *numbers* of emitters
(at fixed drive levels).
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
On 11/09/2023 22:50, Don Y wrote:
I have lots of cameras in my current design (solve problem once, apply
many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
Decide what signal to noise in the video image is acceptable for your application and use only that much artificial light.
One approach is to drive the entire "illuminator" with different
current levels to get varying intensity output.
Another approach is to drive varying *numbers* of emitters
(at fixed drive levels).
If you get down to 1 or 2 LEDs then that is a whole stop difference in exposure, but once you go up to 2 or more LEDs you can get exposure right to the nearest half stop which is good enough for all practical purposes (even back in the days of conventional film).
You effectively want a sequence of LEDs lit up along the lines of:
2 3 4 6 8 11 16 22 32
just like the old f stops on a classical camera.
Beware that if they are too far off axis the lighting profile might change as you switch more distant ones on and off.
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
Using the least amount of illumination you can get away with.
On 9/12/2023 12:28 AM, Martin Brown wrote:
[...]
Beware that if they are too far off axis the lighting profile might
change as you switch more distant ones on and off.
Yes but most seem to be arranged in concentric rings.
I suspect the large numbers are intended just to boost range.
On 9/12/2023 12:28 AM, Martin Brown wrote:
On 11/09/2023 22:50, Don Y wrote:
I have lots of cameras in my current design (solve problem once, apply
many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
Decide what signal to noise in the video image is acceptable for your
application and use only that much artificial light.
I'm trying to come up with *one* camera that I can "adjust"
to suit different scenes.
You effectively want a sequence of LEDs lit up along the lines of:
2 3 4 6 8 11 16 22 32
just like the old f stops on a classical camera.
The cameras I've found (so far) tend to have a lot of emitters
(the one I toredown tonight had ~40). I can afford to move the
emitters *out* of the camera (and disable any that are internal)
but still need the Ir filter, inside, to be operable.
Beware that if they are too far off axis the lighting profile might
change as you switch more distant ones on and off.
Yes but most seem to be arranged in concentric rings.
I suspect the large numbers are intended just to boost range.
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
Using the least amount of illumination you can get away with.
The question is whether that can be obtained by running a bunch
of emitters at a low current *or* a fewer number at a higher
current.
(I've already taken care of the case of using the camera
at an effective lower frame rate for scenes that aren't
changing -- much. But, there's only so much I can do
in software to juggle the power budget...)
On 2023-09-12, Don Y wrote:
On 9/12/2023 12:28 AM, Martin Brown wrote:
[...]
Beware that if they are too far off axis the lighting profile might
change as you switch more distant ones on and off.
Yes but most seem to be arranged in concentric rings.
I suspect the large numbers are intended just to boost range.
The multitude of LEDs in the ring(s) are to ensure the scene is
illuminated clearly. That is, they're less to increase range, and more
to combat things like multiple shadows or other visual artifacts
without resorting to a diffuser.
On 12/09/2023 09:32, Don Y wrote:
On 9/12/2023 12:28 AM, Martin Brown wrote:
On 11/09/2023 22:50, Don Y wrote:
I have lots of cameras in my current design (solve problem once, apply >>>> many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
Decide what signal to noise in the video image is acceptable for your
application and use only that much artificial light.
I'm trying to come up with *one* camera that I can "adjust"
to suit different scenes.
Even so your lowest power budget will still be when you have just enough illumination to do the task at hand (and no more than that).
You effectively want a sequence of LEDs lit up along the lines of:
2 3 4 6 8 11 16 22 32
just like the old f stops on a classical camera.
The cameras I've found (so far) tend to have a lot of emitters
(the one I toredown tonight had ~40). I can afford to move the
emitters *out* of the camera (and disable any that are internal)
but still need the Ir filter, inside, to be operable.
Beware that if they are too far off axis the lighting profile might change >>> as you switch more distant ones on and off.
Yes but most seem to be arranged in concentric rings.
I suspect the large numbers are intended just to boost range.
Probably to act much like a ring flash in close up and macro work to avoid there being any distinct shadows in the field of illumination. That may not always be what you want - off axis illumination casts better sharp shadows that
highlight targets in the field of view.
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
Using the least amount of illumination you can get away with.
The question is whether that can be obtained by running a bunch
of emitters at a low current *or* a fewer number at a higher
current.
I suspect it will be very similar until you start pushing the power LEDs quite
hard. Conversion efficiency only falls off gradually with increasing current until you get fairly close to Imax.
I'd expect several emitters at lower current to be very slightly more efficient
but I doubt it is by enough to make more than 1% saving.
(I've already taken care of the case of using the camera
at an effective lower frame rate for scenes that aren't
changing -- much. But, there's only so much I can do
in software to juggle the power budget...)
You might want to take a look at QCUIAG who are the (amateur astronomy) masters
at tweaking standard webcams for ultra low light use.
http://www.qcuiag.org.uk
Although they mostly want longer exposures and low noise sensors and are very price sensitive. Beginners destroy two or three when learning...
On 9/12/2023 7:46 AM, Martin Brown wrote:
I suspect it will be very similar until you start pushing the power
LEDs quite hard. Conversion efficiency only falls off gradually with
increasing current until you get fairly close to Imax.
What about at the *low* end? Are they as (luminous) efficient
at 10% drive as at 90%? Or 50%?
I'd expect several emitters at lower current to be very slightly more
efficient but I doubt it is by enough to make more than 1% saving.
But, does that extend to the LOWEST end of the range?
I.e., is there a point where I am driving 40 emitters
at a level that *exceeds* the requirements that could
be met with just 20? I.e., I'm just heating extra die
and not getting anything useful from them?
On 9/11/2023 3:11 PM, Lasse Langwadt Christensen wrote:
mandag den 11. september 2023 kl. 23.50.46 UTC+2 skrev Don Y:
I have lots of cameras in my current design (solve problem once, apply
many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
One approach is to drive the entire "illuminator" with different
current levels to get varying intensity output.
Another approach is to drive varying *numbers* of emitters
(at fixed drive levels).
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
if you are trying to save power you'll need a switching regulator so it is trivial to control the output level and controlling the level instead of number won't change the light patternThere are a lot of emitters (in many designs) so I suspect putting every other or third, fourth, etc. in a different string -- still spread out
around the lens -- won't appreciably change the light pattern for the
sorts of scenes where lower illumination is acceptable.
I may opt to excite the illuminator with a higher potential
to get more compliance (some of the cameras I've torn down
have as few as three emitters in a string -- with a dozen
or more strings! This seems like a lot is being lost in the
ballast)
I think I may have to hack together a prototype that
lets me control individual emitters so I can see what the
effect on illumination will be. That might make the driver
choice more obvious...
(the units I've examined drive all of the emitters simultaneously,
regardless of how wired; so, PCB layout is the driving factor,
not "dispersal of light")
tirsdag den 12. september 2023 kl. 08.50.14 UTC+2 skrev Don Y:
On 9/11/2023 3:11 PM, Lasse Langwadt Christensen wrote:
mandag den 11. september 2023 kl. 23.50.46 UTC+2 skrev Don Y:There are a lot of emitters (in many designs) so I suspect putting every
I have lots of cameras in my current design (solve problem once, apply >>>> many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
One approach is to drive the entire "illuminator" with different
current levels to get varying intensity output.
Another approach is to drive varying *numbers* of emitters
(at fixed drive levels).
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
if you are trying to save power you'll need a switching regulator so it is >>> trivial to control the output level and controlling the level instead of >>> number won't change the light pattern
other or third, fourth, etc. in a different string -- still spread out
around the lens -- won't appreciably change the light pattern for the
sorts of scenes where lower illumination is acceptable.
I may opt to excite the illuminator with a higher potential
to get more compliance (some of the cameras I've torn down
have as few as three emitters in a string -- with a dozen
or more strings! This seems like a lot is being lost in the
ballast)
I think I may have to hack together a prototype that
lets me control individual emitters so I can see what the
effect on illumination will be. That might make the driver
choice more obvious...
(the units I've examined drive all of the emitters simultaneously,
regardless of how wired; so, PCB layout is the driving factor,
not "dispersal of light")
I'm sure you will find a way to make something simple extremely complicated ;)
On 12/09/2023 18:44, Don Y wrote:
On 9/12/2023 7:46 AM, Martin Brown wrote:
I suspect it will be very similar until you start pushing the power LEDs >>> quite hard. Conversion efficiency only falls off gradually with increasing >>> current until you get fairly close to Imax.
What about at the *low* end? Are they as (luminous) efficient
at 10% drive as at 90%? Or 50%?
They seem to be linear right down to the point where you can barely see them which for a high efficiency modern LED is somewhere around 1-10uA once your eyes are dark adapted. I'd be surprised if IR LEDs were any different (I found
a datasheet for a suitable one).
It only becomes non-linear and lower efficiency at >Imax/4. eg
https://www.mouser.co.uk/datasheet/2/917/downloaddatafile-2853791.pdf
See the graph of luminous flux vs I_f log log graphs can hide a multitude of sins but that one is die straight for I_f < 1A.
I'd expect several emitters at lower current to be very slightly more
efficient but I doubt it is by enough to make more than 1% saving.
But, does that extend to the LOWEST end of the range?
I.e., is there a point where I am driving 40 emitters
at a level that *exceeds* the requirements that could
be met with just 20? I.e., I'm just heating extra die
and not getting anything useful from them?
In general I think they are so close to linear output unless over driven quite
hard that it is linear to all intents and purposes all the way down to zero intensity.
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by
the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will
also give a 3D effect which helps with recognising people and objects.
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >>window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is >>outdoors and there is the slightest mist, the light will be reflected by >>the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will
also give a 3D effect which helps with recognising people and objects.
Why do evil robots in movies have eyes that glow? That's bad optics.
On Wed, 13 Sep 2023 07:51:50 -0700, John Larkin <jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the
window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by >>> the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will
also give a 3D effect which helps with recognising people and objects.
Why do evil robots in movies have eyes that glow? That's bad optics.
X-Ray vision?
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is >outdoors and there is the slightest mist, the light will be reflected by >the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will
also give a 3D effect which helps with recognising people and objects.
Why do evil robots in movies have eyes that glow? That's bad optics.
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 13 Sep 2023 07:51:50 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >>>> window which reduces the contrast of the scene. If the window 'fogs', >>>> even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by >>>> the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will >>>> also give a 3D effect which helps with recognising people and objects.
Why do evil robots in movies have eyes that glow? That's bad optics.
X-Ray vision?
Its only bad if its unmodulated CW.
Cheers
Phil Hobbs
On Wed, 13 Sep 2023 15:35:37 -0000 (UTC), Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote:
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 13 Sep 2023 07:51:50 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:Why do evil robots in movies have eyes that glow? That's bad optics.
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >>>>> window which reduces the contrast of the scene. If the window 'fogs', >>>>> even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by >>>>> the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will >>>>> also give a 3D effect which helps with recognising people and objects. >>>>
X-Ray vision?
Its only bad if its unmodulated CW.
Cheers
Phil Hobbs
I suppose the illuminator could be nanosecond pulsed and the imager >fast-gated. Get some time-of-flight data too. Maybe some advanced >civilization could do that.
But more likely, movies do that to make evil robots look more evil.
Good robots don't have eyes that glow.
On Wed, 13 Sep 2023 15:35:37 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 13 Sep 2023 07:51:50 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:Why do evil robots in movies have eyes that glow? That's bad optics.
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >>>>> window which reduces the contrast of the scene. If the window 'fogs', >>>>> even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by >>>>> the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will >>>>> also give a 3D effect which helps with recognising people and objects. >>>>
X-Ray vision?
Its only bad if its unmodulated CW.
Cheers
Phil Hobbs
I suppose the illuminator could be nanosecond pulsed and the imager fast-gated. Get some time-of-flight data too. Maybe some advanced civilization could do that.
But more likely, movies do that to make evil robots look more evil.
Good robots don't have eyes that glow.
Why did the reversing cameras in my van come with I.R. illuminators
built-in?
I had to dismantle the cameras and disconnect the L.E.D.s before they
would work properly in dim light. Now the 21-watt reversing lamp gives
more than enough light for the cameras to work properly, even in fog or
heavy rain.
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by
the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will
also give a 3D effect which helps with recognising people and objects.
John Larkin <jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 15:35:37 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 13 Sep 2023 07:51:50 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid >>>>> (Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:Why do evil robots in movies have eyes that glow? That's bad optics.
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >>>>>> window which reduces the contrast of the scene. If the window 'fogs', >>>>>> even slightly, the scene will almost 'white-out'. If the camera is >>>>>> outdoors and there is the slightest mist, the light will be reflected by >>>>>> the droplets straight back into the camera lens making it unusable. >>>>>>
The illumination needs to come from the sides or above or below -- >>>>>> anywhere except directly in line with the camera. Slight shadows will >>>>>> also give a 3D effect which helps with recognising people and objects. >>>>>
X-Ray vision?
It?s only bad if it?s unmodulated CW.
Cheers
Phil Hobbs
I suppose the illuminator could be nanosecond pulsed and the imager
fast-gated. Get some time-of-flight data too. Maybe some advanced
civilization could do that.
;) Thats more or less my current project.
On Wed, 13 Sep 2023 17:35:38 -0000 (UTC), Phil Hobbs ><pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 15:35:37 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 13 Sep 2023 07:51:50 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid >>>>>> (Liz Tuddenham) wrote:X-Ray vision?
Don Y <blockedofcourse@foo.invalid> wrote:Why do evil robots in movies have eyes that glow? That's bad optics. >>>>>
[...] I can afford to move theIn my experience that is by far the best thing to do.
emitters *out* of the camera (and disable any that are internal) >>>>>>>
Having the emitters inside the camera housing causes reflection off the >>>>>>> window which reduces the contrast of the scene. If the window 'fogs', >>>>>>> even slightly, the scene will almost 'white-out'. If the camera is >>>>>>> outdoors and there is the slightest mist, the light will be reflected by
the droplets straight back into the camera lens making it unusable. >>>>>>>
The illumination needs to come from the sides or above or below -- >>>>>>> anywhere except directly in line with the camera. Slight shadows will >>>>>>> also give a 3D effect which helps with recognising people and objects. >>>>>>
It?s only bad if it?s unmodulated CW.
Cheers
Phil Hobbs
I suppose the illuminator could be nanosecond pulsed and the imager
fast-gated. Get some time-of-flight data too. Maybe some advanced
civilization could do that.
;) Thats more or less my current project.
Single-photon timestamp imagers would be cool, much better than charge >integration with occasional readout and dump. But they would create a
lot of data.
Local processing would help. Where have I heard that idea before?
On 9/13/2023 8:55 AM, Liz Tuddenham wrote:
Why did the reversing cameras in my van come with I.R. illuminators built-in?
Hmmmm... odd, that. The cameras on SWMBO's vehicle are just
bare optics, relying on the (LED) brake and backup lights
for scene lighting.
[And gives me a straightforward way to present live video
on that monitor without having to reverse engineer the
entire navigation head!]
I had to dismantle the cameras and disconnect the L.E.D.s before they would work properly in dim light. Now the 21-watt reversing lamp gives more than enough light for the cameras to work properly, even in fog or heavy rain.
Was this an aftermarket product?
Was this an aftermarket product?
Yes, I installed them myself. I tried to get some without LEDs or with
a separate illumination circuit, but they all have the same design
fault.
You can see them in the picture captioned "Cowl Over Ventilation Holes"
at:
http://www.poppyrecords.co.uk/Van/vanconversion.htm
They are at the top of the back doors near the centre line.
On 9/12/2023 12:28 AM, Martin Brown wrote:
On 11/09/2023 22:50, Don Y wrote:
I have lots of cameras in my current design (solve problem once, apply
many times!).
Most instances require Ir illuminators (I am trying to standardize on
a single device "used appropriately" instead of different devices
for the different applications).
I'd like to save power on the illuminators.
Decide what signal to noise in the video image is acceptable for your
application and use only that much artificial light.
I'm trying to come up with *one* camera that I can "adjust"
to suit different scenes.
One approach is to drive the entire "illuminator" with different
current levels to get varying intensity output.
Another approach is to drive varying *numbers* of emitters
(at fixed drive levels).
If you get down to 1 or 2 LEDs then that is a whole stop difference in
exposure, but once you go up to 2 or more LEDs you can get exposure right to >> the nearest half stop which is good enough for all practical purposes (even >> back in the days of conventional film).
You effectively want a sequence of LEDs lit up along the lines of:
2 3 4 6 8 11 16 22 32
just like the old f stops on a classical camera.
The cameras I've found (so far) tend to have a lot of emitters
(the one I toredown tonight had ~40). I can afford to move the
emitters *out* of the camera (and disable any that are internal)
but still need the Ir filter, inside, to be operable.
Beware that if they are too far off axis the lighting profile might change as
you switch more distant ones on and off.
Yes but most seem to be arranged in concentric rings.
I suspect the large numbers are intended just to boost range.
[In each case, closing the loop with video feedback to ensure
I'm not over-illuminating the scene]
Suggestions as to which will give me most *effective* control
vs. power dissipated?
Using the least amount of illumination you can get away with.
The question is whether that can be obtained by running a bunch
of emitters at a low current *or* a fewer number at a higher
current.
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the >>window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is >>outdoors and there is the slightest mist, the light will be reflected by >>the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will
also give a 3D effect which helps with recognising people and objects.
Why do evil robots in movies have eyes that glow? That's bad optics.
On 9/13/2023 1:01 PM, Liz Tuddenham wrote:
Was this an aftermarket product?
Yes, I installed them myself. I tried to get some without LEDs or with
a separate illumination circuit, but they all have the same design
fault.
Are they marketed as "backup cameras"? Or, as just "generic cameras"?
(i.e., in the former case, they should have been able to EXPECT external lighting to be present; in the latter, not)
Part of the problem of using an external illuminator is I
would need to be able to disable the "internal" ones,
yet keep the Ir filter controls (ideally, made external).
[I'm looking at large enough quantities that I can probably just
design what I want and get someone to build them for me. Silly
for folks to put smarts -- CPU, NIC, magnetics, etc. -- in a camera
and then not do any real processing beyond "motion detected"
(YOU looked at the scene; tell me what *I* want to know!)]
Don Y <blockedofcourse@foo.invalid> wrote:
Are they marketed as "backup cameras"? Or, as just "generic cameras"?
(i.e., in the former case, they should have been able to EXPECT external
lighting to be present; in the latter, not)
They were sold as 'Reversing cameras' and came as a kit, with
appropriate long multicore cables and in-line connectors to allow them
to be installed in a vehicle.
Part of the problem of using an external illuminator is I
would need to be able to disable the "internal" ones,
yet keep the Ir filter controls (ideally, made external).
[I'm looking at large enough quantities that I can probably just
design what I want and get someone to build them for me. Silly
for folks to put smarts -- CPU, NIC, magnetics, etc. -- in a camera
and then not do any real processing beyond "motion detected"
(YOU looked at the scene; tell me what *I* want to know!)]
That's far more complex than anything I have dealt with, but it still
needs the basic lighting set-up to be right before embarking on any sort
of software or human analysis.
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the
window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by
the droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight shadows will
also give a 3D effect which helps with recognising people and objects.
Why do evil robots in movies have eyes that glow? That's bad optics.
Baddies and demons usually have red eyes too.
(eg I Robot, Planet of the Ood)
<pcdhSpamMeSenseless@electrooptical.net> wrote:off the
John Larkin <jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 15:35:37 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Joe Gwinn <joegwinn@comcast.net> wrote:
On Wed, 13 Sep 2023 07:51:50 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection
'fogs',window which reduces the contrast of the scene. If the window
reflected byeven slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be
shadows willthe droplets straight back into the camera lens making it unusable.
The illumination needs to come from the sides or above or below --
anywhere except directly in line with the camera. Slight
objects.also give a 3D effect which helps with recognising people and
Why do evil robots in movies have eyes that glow? That's bad optics.
X-Ray vision?
It's only bad if it's unmodulated CW.
I suppose the illuminator could be nanosecond pulsed and the imager
fast-gated. Get some time-of-flight data too. Maybe some advanced
civilization could do that.
;) That’s more or less my current project.
Single-photon timestamp imagers would be cool, much better than charge integration with occasional readout and dump. But they would create a
lot of data.
Local processing would help. Where have I heard that idea before?
Don Y <blockedofcourse@foo.invalid> wrote:
On 9/13/2023 1:01 PM, Liz Tuddenham wrote:
Was this an aftermarket product?
Yes, I installed them myself. I tried to get some without LEDs or with
a separate illumination circuit, but they all have the same design
fault.
Are they marketed as "backup cameras"? Or, as just "generic cameras"?
(i.e., in the former case, they should have been able to EXPECT external
lighting to be present; in the latter, not)
They were sold as 'Reversing cameras' and came as a kit, with
appropriate long multicore cables and in-line connectors to allow them
to be installed in a vehicle.
Part of the problem of using an external illuminator is I
would need to be able to disable the "internal" ones,
yet keep the Ir filter controls (ideally, made external).
[I'm looking at large enough quantities that I can probably just
design what I want and get someone to build them for me. Silly
for folks to put smarts -- CPU, NIC, magnetics, etc. -- in a camera
and then not do any real processing beyond "motion detected"
(YOU looked at the scene; tell me what *I* want to know!)]
That's far more complex than anything I have dealt with, but it still
needs the basic lighting set-up to be right before embarking on any sort
of software or human analysis.
On Thu, 14 Sep 2023 21:36:56 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
On 9/13/2023 1:01 PM, Liz Tuddenham wrote:
Was this an aftermarket product?
Yes, I installed them myself. I tried to get some without LEDs or with >>>> a separate illumination circuit, but they all have the same design
fault.
Are they marketed as "backup cameras"? Or, as just "generic cameras"?
(i.e., in the former case, they should have been able to EXPECT external >>> lighting to be present; in the latter, not)
They were sold as 'Reversing cameras' and came as a kit, with
appropriate long multicore cables and in-line connectors to allow them
to be installed in a vehicle.
Part of the problem of using an external illuminator is I
would need to be able to disable the "internal" ones,
yet keep the Ir filter controls (ideally, made external).
[I'm looking at large enough quantities that I can probably just
design what I want and get someone to build them for me. Silly
for folks to put smarts -- CPU, NIC, magnetics, etc. -- in a camera
and then not do any real processing beyond "motion detected"
(YOU looked at the scene; tell me what *I* want to know!)]
That's far more complex than anything I have dealt with, but it still
needs the basic lighting set-up to be right before embarking on any sort
of software or human analysis.
I'd love to have a backup cam on my 2008 Audi, but installing the
camera and an LCD somewhere sounds nasty.
On 9/14/23 10:14 PM, John Larkin wrote:
On Thu, 14 Sep 2023 21:36:56 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
On 9/13/2023 1:01 PM, Liz Tuddenham wrote:
Was this an aftermarket product?
Yes, I installed them myself. I tried to get some without LEDs or with >>>> a separate illumination circuit, but they all have the same design
fault.
Are they marketed as "backup cameras"? Or, as just "generic cameras"? >>> (i.e., in the former case, they should have been able to EXPECT external >>> lighting to be present; in the latter, not)
They were sold as 'Reversing cameras' and came as a kit, with
appropriate long multicore cables and in-line connectors to allow them
to be installed in a vehicle.
Part of the problem of using an external illuminator is I
would need to be able to disable the "internal" ones,
yet keep the Ir filter controls (ideally, made external).
[I'm looking at large enough quantities that I can probably just
design what I want and get someone to build them for me. Silly
for folks to put smarts -- CPU, NIC, magnetics, etc. -- in a camera
and then not do any real processing beyond "motion detected"
(YOU looked at the scene; tell me what *I* want to know!)]
That's far more complex than anything I have dealt with, but it still
needs the basic lighting set-up to be right before embarking on any sort >> of software or human analysis.
I'd love to have a backup cam on my 2008 Audi, but installing the
camera and an LCD somewhere sounds nasty.
I figured that surely there was a wireless solution these days.
Either find a +12 that's always hot when key is on if you want that, or
tap into one of the backup light feeds so it only comes on in reverse.
On 13/09/2023 15:51, John Larkin wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
[...] I can afford to move the
emitters *out* of the camera (and disable any that are internal)
In my experience that is by far the best thing to do.
Having the emitters inside the camera housing causes reflection off the
window which reduces the contrast of the scene. If the window 'fogs',
even slightly, the scene will almost 'white-out'. If the camera is
outdoors and there is the slightest mist, the light will be reflected by >> the droplets straight back into the camera lens making it unusable.
Ideally you want something to cast a rain shadow onto the camera lens or window - something that not all motorway monitoring cameras have.
On 2023-09-12, Don Y <blockedofcourse@foo.invalid> wrote:
On 9/12/2023 12:28 AM, Martin Brown wrote:
Suggestions as to which will give me most *effective* control
vs. power dissipated?
Using the least amount of illumination you can get away with.
The question is whether that can be obtained by running a bunch
of emitters at a low current *or* a fewer number at a higher
current.
Then the answer is YES!
However current can be varied in more steps than emitter count can.
On 2023-09-13, John Larkin <jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
Why do evil robots in movies have eyes that glow? That's bad optics.
Arthur C. Clarke and Stanley Kubrick started it.
https://villains.fandom.com/wiki/HAL_9000
On 14/09/2023 08:46, Jasen Betts wrote:
On 2023-09-13, John Larkin <jjlarkin@highlandtechnology.com> wrote:
On Wed, 13 Sep 2023 13:57:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Don Y <blockedofcourse@foo.invalid> wrote:
Why do evil robots in movies have eyes that glow? That's bad optics.
Arthur C. Clarke and Stanley Kubrick started it.
https://villains.fandom.com/wiki/HAL_9000
I think Terry Nation's Dr Who Daleks ~1964 were amongst the first evil
robots to have glowing eye stalks but what colour they were is hard to
say since it was B&W. Here is one rising out of the water under London.
https://en.wikipedia.org/wiki/The_Dalek_Invasion_of_Earth#/media/File:Dalek_Invasion_of_Earth.jpg
I suspect that on their first appearance in 1963 the eye stalks didn't
glow largely because the special effects had run out of time and money.
On 2023-09-15, Martin Brown <'''newspam'''@nonad.co.uk> wrote:
I suspect that on their first appearance in 1963 the eye stalks didn't
glow largely because the special effects had run out of time and money.
a small battery powered lamp, but yeah I guess the line has to be
drawn somewhere.
On 15/09/2023 22:37, Jasen Betts wrote:
On 2023-09-15, Martin Brown <'''newspam'''@nonad.co.uk> wrote:
I suspect that on their first appearance in 1963 the eye stalks didn't
glow largely because the special effects had run out of time and money.
a small battery powered lamp, but yeah I guess the line has to be
drawn somewhere.
I still remember meeting a Dalek (voice and all) at a BBC event as a
young child - they were pretty scary! Not as scary as cybermen though!! >(cybermen can climb stairs)
I used to have this cartoon on my office wall at university: >https://twitter.com/PunchBooks/status/1511392231147683844
My office mate had this one but with green snot. >https://www.pinterest.co.uk/pin/989525349358461609/
I have a friend who had a real ex-BBC Mk I Dalek in his living room!
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