Calculate speed moving object - IPC-T5442T-ZE - BI

S0619212

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I am using BI for Dahua IPC-T5442T-ZE . Is there a way to display speed of a moving object? We had an issue last night where kids were playing outside on the neighborhood street right infront of our house, we had two cars at two different occasions speeding towards the end of the street, my 3 yr old was playing outside, we were all right there but it happened in a flash, the car came speeding and we all had to yell at the driver to slow down, she did eventually slow down ( turns out she was Uber eats delivery person) . When i went back at looked at the recording, it didn't really look like she was speeding, to make proper judgments it would be really nice if BI or Dahua can actually display speed also.
 

sebastiantombs

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That' nice in theory but in practice it's extremely difficult. Think about what you're asking for and how it would be able to be "built in" to a camera or BI. Distance to the target, angle of motion and distance traveled are all critical to be able to do a calculation like that. Time involved in the target travel would be easy to extract though. Other than time, the rest are variable depending on the installation location in every case and actually measuring them would be way more than the average surveillance user is willing to do. Much easier to get a cheap radar gun and in either case, none of it would hold up in court anyway since it wouldn't be certified by any recognized agency.

In the case of a varifocal or zoom camera it would be even harder to calculate with any accuracy.
 
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IAmATeaf

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You could drive past your cam at fixed speeds which could then be used as a gauge, not precise by any stretch of the imagination but might give you a baseline to approximate the speed of other drivers?
 

sebastiantombs

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Yes, you could, but once again it isn't worth the pixels it's written on in terms of anything involving the law. Plus, using a cheap radar gun would be much more accurate.
 
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DsineR

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All the numbers are there to calculate the speed, but as mentioned above the numbers are not exact.
Ex. your cam has a horizontal image coverage of 50', and you record how long it takes for the car to travel from beginning to end of the frame - say 2 seconds.
Car Speed = 25f/s, or 17.05mph
 

djborden

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Correct, I assume you can measure the distance of the street that is in frame then use the time stamps for when the nose of the vehicle enters the frame and when the front of the car breaks the other side of the frame and do the math to calc speed.
 

usaf_pride

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brianegge

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I’ve done the side view AI object detection to calculate speed, which works well enough for ones own amusement. Are there any cheap radar guns that put a text overlay?
 

wittaj

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Just do it right LOL

 

SyconsciousAu

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I was bored one weekend and played around with this for a bit. I couldn't get the software to access my camera and in the end I gave up because life got in the way. You may have more success.

 

aristobrat

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I was bored one weekend and played around with this for a bit. I couldn't get the software to access my camera and in the end I gave up because life got in the way. You may have more success.

That looks interesting!
 

sebastiantombs

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Unless the camera has a broadside view the calculation will be even more of an approximation. Yes, you can count frames or do simple subtraction to determine time and can mark/measure the scene, but it's still "eyeball" science. Fun to do, but of little real value.
 

wittaj

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^ That looks interesting and with the right camera setup, would probably work good - did you just try the demo version?
 

SyconsciousAu

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but it's still "eyeball" science. Fun to do, but of little real value.
It's just an average speed calculator. They use the same principle to do speed enforcement around the world.



Tough part will be the limited field of view. The longer you can track for the lower the error will be. There is also no verifiable calibration, but if your intention is just to name and same, none of that will really matter.

^ That looks interesting and with the right camera setup, would probably work good - did you just try the demo version?
Yeah just the demo. I couldn't get it to open the camera stream, so it was a no go from the beginning.
 

wittaj

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Sweet - hopefully I can try setting it up today and trying - I have a perfect straight on view with two cracks in the pavement that will make for an easy measurement.
 

sebastiantombs

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Funny, I thought radar, due to the number of samples in a very short time period, was a little more accurate. As I have said previously, a nice exercise in math but not worth anything since it is an estimate based on eyeball science.
 

wittaj

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Many states allow speed enforcement by patrol in aircraft, which is timing of a vehicle between two known distance markers.

Ever notice a white stripe on the interstate perpendicular to the lane lines - those are for patrol by air. Speed measurement markings may extend 24 inches on either side of the center line or 24 inches on either side of edge line markings at 1/4-mile intervals over a 1-mile length of roadway. When paved shoulders of sufficient width are available, the speed measurement markings may be placed entirely on these shoulders. Advisory signs may be used in conjunction with these markings.

Granted none of us probably have a FOV of one mile to do this with a camera LOL.
 

sebastiantombs

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That's how they eliminate the error of visual speed measurement, a one mile sample makes the error insignificant compared to the error at 10 or 100 feet. Again, a nice exercise in math, but not accurate at all and worthless to the police or in court. In fact I'd bet the Town Council, as dumb as they can be, wouldn't be very interested either.
 
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