Dedicated License Plate Cam project

[SyconsciousAu]

this looks nice: http://s.click.aliexpress.com/e/bifGiReg

Know any sparkies who can hook you up for a slab? That looks like the goods and the price seems right. I would have hit buy myself if it was rated more than 220V, but unfortunately for me Australia runs 230V AC with +10% - 6% tolerances, and 253V is not good for 220V rated equipment. Im limited to their 12V capable offerings. I really like the look of that model though.

 

[nayr]

yeah me, heh.. I am keen on getting one of those for my side yard now that Ive found it, I have a 120v bug-zapper on the back side of the fence hardwired in, could just put that on the fence blasting out, I think a 60 degree one would fire up every thing to the neighbors across the way with very high detail.

went ahead and pulled the trigger on one of the bullet ones because they finally went back on sale: http://s.click.aliexpress.com/e/p7rLWw4

it has 3x4.5W=13.5W of 850nm IR's and I can focus it down to such a narrow beam that I need.. math works out so it almost doubles the range each time you focus it in half the space.. this design kept coming back to the winner for its optics and small size. I'd like to recess it into the rock a bit so the glow disappears when viewed from any angle but dead on.. and slow but free shipping.

I really dont think I need 28/30w of power for LPR at this range, I know my black face dahua is not putting out near that.. probably 6-8W tops with all the IR on.

 

[pozzello]

i think the bullet is substantially less conspicuous than the 20w panel, which is the one i thought may have
contributed to some guy poking around our front door. the panel has a wider pattern (15 degrees vs ~5 at narrowest spread.)
Also, the panel has much more bleeding outside the main lighted area. i think they rate those beam widths at 50% of
max intensity, and the panel LEDs can be seen more off-angle. the bullet has quite a drastic edge to that beam,
as shown in my image reposted above, which will help throw that light further. i'd bet most drivers seeing it would
just think it was just something reflecting off their headlights. curious pedestrians might figure it out, but as far as i know,
there's nothing illegal abut what we're doing, so if they don't like it, too bad...

 

[nayr]

did some tweaking today with positions, played with a bunch.. tried harsher angles with more zoom and a few different options.. most of them bust.

I did get better positioning than I had and maxed out the zoom, average plate capture are now ~150px in height (@1080p) and that has yielded another dramatic improvement in reading accuracy.. and as a side bonus I can see pedestrian traffic on both sidewalks durring the day.

seem to have hit a really good view/config right now.. at least for daytime.

if you have anything big white square in frame it's going to mess up OpenALPR, neighbors white mailbox it kept trying to read.. then his white wire picket fence was messing me up too.. could not have any of those in frame.

Considering modifying plans from faux rock to birdhouse, just so I can get it higher off the ground to avoid snow blocking the view for weeks on end.. got it on a ladder right now and i like the angle.

 

[nayr]

today I bumped the day time shutter speed up to 1/1500s, got rid of a bit of blur from hella speeders.. I think the BLC had a bit to do with it but I have to have it in the day to keep the glare down.. seems to like it here without much gain in the daytime so I'll leave it.. I switch day/night profiles externally at sunset so I can have completely different settings in day than night.

attached are my current image settings, I am recording substream 24/7.. I cant record sub-stream #2 (720p) natively but I think I can if I add the feed as a generic camera, so I might just have to live with 720p 24/7 recordings and 1080p snapshots.. I am good with that, just want the video incase I happen to catch an accident or theft.. I am not storing the MJPEG thats for sure so no line cross detection unless I knock ALPRD down to 720p

Main Stream: 1080p/6fps @ Full Bitrate MJPEG - OpenALPRd
Sub Stream #1: D1 (PAL)/25fps @ Full Bitrate H264 - Live Displays
Sub Stream #2: 720p/25fps @ Full Bitrate H264 - 24/7 Recording.

Getting the focus right has been a bit tricky, oncoming plates are further away than rear end plates.. trying to find a compromise means focusing on the further ones because the bigger ones are easier to read.

I am pretty much perfect reading on all rear end plates, and pretty good accuracy (acceptable) on front end plates..

odd, the neighbor with the big problematic white mailbox just took it down.. hah, here is hoping he puts a black one up

the lens's IR correction is not that great a you can see from the pedestrian, it gets better as they get into focus but its not really a problem with plates so meh.

 

[ruppmeister]

@nayr what's with the blue glow that is around everything in your pics? I can especially see it around the pic with the woman. Part of BLC artifacts perhaps?


Sent from my iPhone using Tapatalk

 

[nayr]

I suspect its IR, this setup does not have an IR Cut filter so I got a lens that was supposed to be IR Correcting, but for objects out of focus I can see the glow if they are in sunlight.. as they come closer to focus the IR glow gets better and harder to notice.. for plates it seems to have no impact, its not adding any blur or noise to the plate.. likely because its reflecting the IR back towards the sun.

turning on BLC makes it more apparent, its much less noticeable with BLC disabled.. but if you look closely you can see it still.. some objects reflect more IR more than others and thats why I think its IR artifacts, that white shirt is just glowing.

 

[SyconsciousAu]

I am recording substream 24/7..

Don't you end up with nothing but video of a black bear in a coal cellar after the sun goes down?

Getting the focus right has been a bit tricky, oncoming plates are further away than rear end plates.. trying to find a compromise means focusing on the further ones because the bigger ones are easier to read.

Do a bit of reading on depth of field and hyperfocal distance.

http://www.dofmaster.com/dofjs.html

You may have to get a focus target out there and focus it in sharply, rather than just doing it by eye with the auto focus taking over from there. I used my car as a focus target to get mine set up properly. Your depth of field changes depending on zoom, focus point, and aperture setting. I force a stupidly large aperture by setting the shutter speed really high when I am setting up by day. It forces the auto iris to open all the way. The larger your aperture (smaller F Number) the smaller your depth of field. If you get your depth of field set correctly at your largest aperture setting, it can only get bigger as the aperture gets smaller.

Have a play around with the linked calculator to see where you best focal point is. You can select a 1/3 image sensor.

 

[nayr]

typically I would expect so, but with a good snow fall night almost turns into day and that corner is where all the fun happens.. so even in a black image I could catch some headlamps and tail lamps twirling around as someone comes down the hill sideways... I also kinda hope my IR is going to light up the eyes of any coyotes/foxes that come through at night.. I usually catch them coming down the road from this direction.

I also occasionally run into a plate obscured by a trailer hitch or bike rack, those plates are often readable on video as the perspectives change but never completely at once.. incase I ever need a better read on those cases I'll keep the video around for a lil bit.. I overshot my storage needs by a big margin, Ive got 10TB to work with so I am good on that front.

thanks for the advice on setting the focus to infinite, I will defiantly try to achieve that.. I think I did with my earlier position but I have not got it back with this new location.. unfortunately I cant park anywhere in frame, that was by design heh.. I'll block someone's driveway to park on the side of street in frame.

I think the problem is when I get it into hyperfocus, the rear end plates are so close they are under the minimum distance.. it says with my setup hyperfocus starts at 383ft to infinity.. I'd have to back it off under 40mm to get hyperfocus and tha'll hurt my plate sizes too much to be worth it.

Ive got an old license plate on a stand Ive been sitting on the sidewalk to assist me in focusing, need to print out a whole focus chart and add it to my stand with the plate.. I havent been using the auto back focus much, but I have been adjusting it manually with pretty good luck.

Calculated up JPEG storage requirements today, I am getting ~200MB of imagery a day, now thats not including night plates but the traffic at night is much less.. but either way I am looking at way less than 100GB of storage for a year's captures so I'll likely keep plate images indefinitely.

 

[nayr]

another big leap in performance today, simply by updating OpenALPR, gotta love that right!?

new feature: detection_mask_image

; Specifies the full path to an image file that constrains the detection area. Only the plate regions allowed through the mask ; will be analyzed. The mask image must match the resolution of your image to be analyzed. The mask is black and white.
; Black areas will be ignored, white areas will be searched. An empty value means no mask (scan the entire image)
detection_mask_image =

I set this up so it would no longer try to grab plates of cars too far down the road to have any hope of reading it.. blacked out about 40% of the image with ample saftey after reviewing a ton of captures.

End results are I am now getting too many captures hah, at least 3 successful reads per second based off timestamps, up from 1-2.. vehicles outbound I would get 1-2 captures of the plate and inbound would net 2-3 captures of the plate (readable ones, there would a couple unreadable ones in distance).. now I get 3-4 captures outbound, and 4-6 captures inbound.. even though I no longer track them further down the road I am getting more images of them hah

So now I am tempted to bump the resolution up another notch just because I think I can, masking the image out has been great and i have yet to even touch any of the other settings.. they are all still default.. if I can go all the way up to 4MP I can zoom out a ways and then mask off a 1080p sized area of interest.. might give me the ability to hyperfocus this shit.

This is also great for those annoying mailboxes and other things that will throw off ALPR, mask em out without a privacy mask on the feed.

edit, actual numbers
without mask:

# alpr --clock galileo-cam1-1459903274844.jpg 
Total Time to process image: 632.249ms.
plate0: 10 results -- Processing Time = 32.5853ms.

with mask:

# alpr --clock galileo-cam1-1459903274844.jpg 
Total Time to process image: 350.136ms.
plate0: 10 results -- Processing Time = 30.3001ms.

so mask has nearly doubled the speed

 

[SyconsciousAu]

I think the problem is when I get it into hyperfocus, the rear end plates are so close they are under the minimum distance.. it says with my setup hyperfocus starts at 383ft to infinity.. I'd have to back it off under 40mm to get hyperfocus and tha'll hurt my plate sizes too much to be worth it.

If the camera has the ability, set your auto iris to F4.0. That brings your hyperfocal point down to 268.6 feet and gives you sharp images from half that to infinity. You still keep the zoom at 60mm. Downside of course is that F4 is about 3 stops smaller than F1.6 so you get 1/8th the light than at F1.6.

 

[pozzello]

as for the detection_mask_image feature in ALPR, that's good to know about, but can't one do pretty much
the same thing with the camera's and/or BI's privacy mask and/or ROI (aRea-Of-Interest) features?

 

[nayr]

I am reading plates right now @ 200ft for oncoming & 150ft for outbound..

and the camera does has auto-iris on/off, no manual iris setting.. I'll keep playing with it but I dont care if distant objects are in sharp focus

 

[nayr]

@pozzello, detection mask only scans a certain part of the image for plates.. you can privacy mask off half the image, now you cant see it.. and ALPRD wont run any faster becuase its still processing the whole image, regardless of your camera's masking.

this is why the speed doubled when I masked off almost half of my 1080p images.

here is my mask:

 

[nayr]

so had to move alprd off my FreeNAS, it was impacting performance too much..

I have another 6 core 3Ghz phenom w/16GB ram sitting mostly idle for odd jobs so I moved it over there.. now its on bare metal and I am tempted to see if I can find an NVidia card to stuff into this server and see how well that offloads the work.

only alprd is running:

load average: 1.18, 1.15, 1.14

%Cpu(s): 18.1 us, 0.2 sy, 0.0 ni, 81.7 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st

 

[nayr]

had to put the camera in something before a freak rain storm ruined it.. so I made a birdhouse out of composite trex.. I'll paint it up when I am ready to mount it.

 

[pozzello]

nice. birds will be confused when they try to move into it.

btw, what's that giant rebar grate for? a grill, maybe? or to cover/secure a basement window well?

 

[nayr]

its my camp bbq, fits on the tongue of my trailer under the fridge.. made it my self, its longer than most firepits are in diameter so I can stack wood on either side and set the height to that perfect steak cooking temp.

when the trailer is not in camping config (ie, no fridge) it just rattles around and adds weight, so it leans up against the fireplace..

back to the birdhouse, its heavy as shit since I made it out of trex heh.. it could survive a tornado, going to shingle the roof too when I go to paint it.. I left just enough room under the camera for the illuminator, the illuminator will either be on constantly or I will have to use the alarm output relay to turn it on/off.

Anyone have any idea what black material they use on IR covers? would like to find some of that to cover the hole for the illuminators.. found photographic 850nm IR Filters for cheap but they look like the'll reduce output by a huge margin.. maybe some cheap film.

 

[cball]

had to put the camera in something before a freak rain storm ruined it.. so I made a birdhouse out of composite trex.. I'll paint it up when I am ready to mount it.

@nayr can you tear the cam a little more backwards. Than you should be able to make the hole smaller an the cam isn't seen anymore especially when the objective ring is no longer seen.

 

[SyconsciousAu]

Anyone have any idea what black material they use on IR covers?

An IR longpass filter is what you are after.

http://www.edmundoptics.com/optics/optical-filters/longpass-edge-filters/optical-cast-infrared-ir-longpass-filters/1918/