Cheap ($90USD) 300 feet varifocal mod LPR test

[clacks]

I detailed my long range varifocal mod in the Dahua sub Simple Dahua bullet cam 50mm vari-focal mod as my original purpose wasn't so much for license plates as people but as I've been refining my settings, I found using plates was the best to get shutter and lighting settings right for better people recognition.

I figured an entry level camera would have no hope of reading at night through light beams but gave it a go and was blown away how I could get 80m (266 feet) plates quite easily.

Anyway playing with cameras is fun and maybe it this may help someone who's budget doesn't extend to the more suitable off the shelf cameras.

100m(333 feet) is at the edge of the image which isn't as sharp as the middle due to my cheap varifocal (or maybe me) so if there is interest I can turn the camera to another road that is 1000 feet and test.

The link above details the process but the two items used:
4Megapixel Varifocal Lens 5-50mm M12 Mount ($30)
Original dahua IPC-HFW4433M-I2 ($60 12mm version in case that matters for IR)

All distances are estimated via google maps and speed would be around 40km/h (25mph).

Day settings (changes from default) but still not optimized as too much light I think:
Manual exposure:0 to 1 ms HLC:80

55m(183 feet)




90m(300 feet)



Night settings (changes from default) again not too refined:
Manual exposure:1/250th sec WDR:50 SmartIR

The specs say the IR light is rated 80+m and this street sign is 100m (333 feet) from my camera (it is pretty much face on however which I see makes a big difference with IR reflection). This is the only light area visible, everything else is pitch black at these camera settings.



55m(183 feet)





80m(266 feet)

 

[bigredfish]

Good job. Kinda goes to prove that perhaps the most important thing with LPR is angle of attack.

Consistency is important as well, do you think you can get something approaching 90%?

 

[clacks]

Good job. Kinda goes to prove that perhaps the most important thing with LPR is angle of attack.

I'd say cars are at 50m(166 feet) when they come around a corner and square on with the camera. The two distance pics in my first post look similar on angle offset which is about 10degrees according to google.

Consistency is important as well, do you think you can get something approaching 90%?

I don't know if you mean optical recognition LPR software or manually reviewing but I'd say definitely above that at 60m(200 feet) from what I've seen and if you have the luxury of frame by frame probably fair bit more.

I'm having space issues that is seeing footage deleted so can't review a few nights but that is sorted so I'll report back when I have a decent amount of cars and give an honest ratio at a set distance and furthermost frame by frame identification.

 

[clacks]

I've looked at about 20 cars now and I'd say 100% clear plate (at night) is about 60m(200feet) then drops off after that until you need to go frame by frame.

With this image last night, I could make out plate frame by frame at maybe 50feet past this but I needed to wait to about 55m(183feet) to get the whole plate in one image.

 

[Tekbotslaya]

How does this set up compare to a IPC-HFW5241E-Z12E at 200ft? I may be mistaken but I recall someone said that 200ft is pushing it for the IPC-HFW5241E-Z12E whereas this set up seems to be doing quite well.

 

[clacks]

How does this set up compare to a IPC-HFW5241E-Z12E at 200ft? I may be mistaken but I recall someone said that 200ft is pushing it for the IPC-HFW5241E-Z12E whereas this set up seems to be doing quite well.

I didn't read much on the two Dahua models that were often mentioned here as they were outside my budget (3 of these modded cameras were cheaper than 1 of those models) but I did take a long time to make the decision as I thought the extra 14mm FOV (probably closer to 20mm as I don't have the whole range due to focal range) and assumed better lens quality over the cheapest aliexpress varifocal might make enough difference to justify. Also the entry level 4MP sensor in low light conditions.

But very pleased with the image quality from both the cheap lens and the cameras sensor in all light conditions.