I’ve had a surveillance system for a few years now and have good coverage of my property, but I intentionally aimed them to minimize overlap into adjacent properties as I didn’t want to intrude into their privacy. A neighbour was robbed a couple weeks back, however, and that’s made me reconsider some of those decisions after talking with him and the others around me. We did get clear shots of the side of the bad guy’s truck when it drove past my house and turned into his driveway, which gave police a timeline as well as make/model/year/trim but no licence plates or faces as the video was perpendicular to his travel. I was able to look back on the footage and find what appeared to be the same vehicle casing the place out a few days before, but again no plates and it was a royal pain to manually pour through all that footage.
I’m flirting with adding another camera shooting up or down the road to try and get the front/back of passing cars for some identifying information should something like this happen again. Ideally I’d like to run some sort of ALPR software to be able to search for that quickly, but for the time being I’d be happy to just have something that would capture close-up photos I could cross reference against the wide-angle view of the road I already have. In this case the Police were at my door asking for access to the footage within 20 minutes of the burglars leaving, so even if the truck was stolen it’s possible a licence plate may have been enough for them to catch them.
The tricky thing is that my house is set back about 65’ with a bunch of trees in the front yard to work around, so I’ve got a few questions before I go out and buy a camera and start fiddling around with this:
I’m flirting with adding another camera shooting up or down the road to try and get the front/back of passing cars for some identifying information should something like this happen again. Ideally I’d like to run some sort of ALPR software to be able to search for that quickly, but for the time being I’d be happy to just have something that would capture close-up photos I could cross reference against the wide-angle view of the road I already have. In this case the Police were at my door asking for access to the footage within 20 minutes of the burglars leaving, so even if the truck was stolen it’s possible a licence plate may have been enough for them to catch them.
The tricky thing is that my house is set back about 65’ with a bunch of trees in the front yard to work around, so I’ve got a few questions before I go out and buy a camera and start fiddling around with this:
- How important is it to get the angle down to 30 degrees or less vs the other tradeoffs? If I point the camera east I can position it to look right underneath a street light just past a stop sign (ie very well lit and cars will be moving slowly due to the intersection), but because of obstructions the best I could get would be about 42 degrees. If I point it west I can get the angle down to 25 degrees but it’s mid-block (ie they’ll be moving at full speed) and pretty dark. The former position would be about 100’ and the latter around 140’. Speed limit is 40km/h (~25mph) which is about what people travel at (there’s lots of intersections so not much time to accelerate before they have to stop again).
- How critical is the vertical angle to making plates identifiable? All of the above is because I’m trying to keep it just above the ground level windows, but if I went up to the second floor I could shoot over most of the obstructions and look further down the road (reducing the horizontal angle and better utilizing the street lights and stop signs). It’d be more of a pain to install up there and while I’d normally write that off as a one-time annoyance, it looks like there’s a lot of fine tuning involved in this application so I might have to go up there a lot.
- I’m looking at the Dahua Z12 cameras given everything I’ve read here; how sensitive are these in low light? I’ve got a 400mm lens for my DSLR that roughly correlates to the 5 degree FoV these have fully zoomed in which I can use to test angles, but I’m not sure how to simulate the exposure to figure out what I’d be looking at to get the appropriate shutter speeds. The minimum illumination spec is listed in the context of 30IRE, but if I understand it right that wouldn’t yield a particularly useful image - if you guys know the minimum lux you’d judge as usable I can calculate the corresponding EV and work from there? Naturally I’d likely be using IR at night, but I’d like to get an idea of what that street light could do.
- Are there any ALPR software packages that can be purchased outright? OpenALPR looks great, but it’s utility is not worth $50/mo for my limited uses - I don’t mind paying for something, but I’d strongly prefer something with a perpetual licence. The free tier would work, but with only two days of retention I’m not sure it’s worth the trouble vs just manually reviewing footage. The only time I see myself looking at the database would be if something happened and I wanted to quickly check if that car had been here before (to then check the other videos and see what they were doing).
- Unrelated to LPR, but as I’m here anyway - when they broke into my neighbour’s place they disabled his security system and dug through his wiring closet likely looking for surveillance recorders. Naturally, all the cameras in the world will do no good if they make off with the recordings - do you guys do anything to protect against that scenario? I’ve hidden my DVRs, but there’s a whole gaggle of wires converging on that point so if someone knew what they were doing they could probably find it. Streaming terabytes of video off site seems like expensive overkill - maybe set up a computer somewhere else in the house and pull video from the DVRs to store a second copy?
