You should have waited one day.I was kidding about pizza:30 Sorry about that
How to capture multiple plate reads in quick succession?
- Thread starter smallik
- Start date
So based on all the tweaks I've made with everyone's great suggestions, would it be fair to say my little NUC computer (which obviously can't accommodate a GPU) is simply not capable of processing 2 and 3 car's plates in quick succession? Here's one of my latest plate grabs with the processing times from both BI AI inspector and CPAI. What do you think?
I am not sure that's the conclusion. My understanding is that as long as your BI is actually sending images with multiple plate, and as long as CPAI is able to process it before the timeouts on BI, this should work. Images are queued on BI until timeout, and if you hit timeout, it stops processing--but unless your queue is very deep, it might not be a problem.
I think the larger issue might be that you are running it all on the same machine and using CPU for CPAI. This makes BI and CPAI compete for cycles and can cause misses? You'd have to look at your system metrics to see if that's the case.
You might want to consider using Rockchip SBC for CPAI. It's cheap and seems to work pretty well. Or if your Minisforum has TB3/4, you might be able to get an external GPU.
I think the larger issue might be that you are running it all on the same machine and using CPU for CPAI. This makes BI and CPAI compete for cycles and can cause misses? You'd have to look at your system metrics to see if that's the case.
You might want to consider using Rockchip SBC for CPAI. It's cheap and seems to work pretty well. Or if your Minisforum has TB3/4, you might be able to get an external GPU.
"Images are queued on BI until timeout, and if you hit timeout, it stops processing--but unless your queue is very deep, it might not be a problem."
Could you explain how I may determine if my queue is deep enough and if it's possible to change its size.
"BI and CPAI compete for cycles and can cause misses? You'd have to look at your system metrics to see if that's the case."
How/where would I check my system metrics?
"You might want to consider using Rockchip SBC for CPAI"
This one's way over my head.
"if your Minisforum has TB3/4, you might be able to get an external GPU"
Only USB3.2 on the Minisfourm.
Thanks
The settings are on BI, under the AI tab:
The help file explains:
Rockchip SBC:
And it's performance:
See avg inference time at the bottom.
Yeah, I use a CPU and it is fine for the database. If you analyze 30 frames at 500 ms per frame (worse case), it takes 15 seconds. Unless you are on a busy street who cares.
These are my settings. I appreciate the explanation you provided with your settings, however with that said, do my setting look like I'm asking for my hardware to do too much? Also the Rockchip board looks affordable enough but I have no idea how to interface it with my Win 11 NUC. Any guidance would be welcomed.
Those look like the default, you can try bumping timeout to 30s or 45s if you believe it's taking a while for CPAI to return the results. If it's taking too long, then consider the Rockchip board, but I think you should take a closer look at your triggers and the DAT file first.
Pay close attention to the very first image sent to CPAI and the very last image sent, and when CPAI is able to pick up the plate number. That gives you an idea of if your triggers are too late or too early. Looks like your are capturing in the middle of the road where the vehicles are all moving along at decent speed. For vehicles traveling left to right from the camera view, the first image sent to CPAI should be when nearly the entire vehicle is in frame, in the subsequent few images, the license plate should be in the middle of the frame. Adjust your triggers to get to this point. @wipman gave you some great suggestions, especially with the fps. I've found that lowering the fps helps.
As soon as you've found this sweet spot, adjust the # of frames you are sending and end the alert asap so that it can be ready for the next trigger.
I spent days play with these settings to get my cameras to work reasonably well, but I still can't catch every plate, so I am far from an expert, I am sure others can give you better directions.
I have an Orange Pi and I am not sure I get much better results than my Xeon E3 which is probably 10 years old at this point. Agree-- bump that timeout to 60.
7W to do it on the Orange Pi vs 180W on your Xeon.
I'm in California, where power is more expensive than Fentanyl.
Very true... but the Xeon runs my NAS 24/7. Incremental cost is negligible. I think I am the once who convinced Mike Lud to use the RKNN libs. I probably should use it.7W to do it on the Orange Pi vs 180W on your Xeon.
I'm in California, where power is more expensive than Fentanyl.
According to this... Massachusetts and California has the same average price for electricity. I am a good candidate for Solar too. I should do it.
Electricity Rates by State | April 2025
Electricity rates by state and zip code. Compare real-time residential and commercial energy rates across the United States.
www.electricchoice.com
My power bill use to be $800/month before the PG&E rate increases. Now I'm at around $350-400/month.
That site is wrong for CA, it's much higher:
# This is effective Jan 1 2025:
# Total Energy Rates ($ per kWh) PEAK PART-PEAK OFF-PEAK
# Summer Usage $0.62 (R) $0.51 (R) $0.30924 (R)
That's an avg of $0.48/kwh. That's why all my servers, routers, switches, etc were refreshed and now run on tiny ARM based stuff now.
That site is wrong for CA, it's much higher:
# This is effective Jan 1 2025:
# Total Energy Rates ($ per kWh) PEAK PART-PEAK OFF-PEAK
# Summer Usage $0.62 (R) $0.51 (R) $0.30924 (R)
That's an avg of $0.48/kwh. That's why all my servers, routers, switches, etc were refreshed and now run on tiny ARM based stuff now.
Here is what I am averaging... I should keep the time sensitive AI stuff on the Xeon and move the database stuff to the RKNN.
Yesterday I changed the timeout to 30 for starters, and for the first time I believe, BI and or CPAI was able to ID two plates during the pass (even though one was not a real plate) and ALPR Database was able to break it out as two unique plate numbers. First time! You may have steered me on to something. Heavy rain today so repeat opportunities my be far and few between to duplicate this but when/if it does, I'll report back. Thanks
Jinxed myself. This pass you would have thought would have been an easy grab for the two but it only logged the first vehicle. Oh well.
Will do. Cars pass by about 1 every 2-5 minutes on average during the busy time. Obviously I get the random 6 in 1 minute every now and then. Thanks
Beyond trying to perfect logging multiple plates in quick succession, I now realize I'm missing lone cars in perfect lighting and focus about 1 in 3 or 4 cars. Here's the car pic and process logs from CPAI. The only standout thing I see is the "Timeout connecting to the server" line. Has anyone experienced this issue before? The plate was clearly found but never made it to the Alert column or ALPR Database (version 0.1.8).
