IVS Intrusion area inconsistent

N

nelsonr

n3wb
Sep 1, 2019
12
6
Maryland
I have a Dahua IPC-HDW2231R-ZS camera (2mp starlight varifocal). In setting up IVS intrusion I am able to set the minimum size of the object. I selected "Min Size" and "Draw Target", which resulted in the blue-ish box you see near the middle. It looks fairly square, but below it resulted in a rectangle of 236x419:

1579891135397.png

If I go to the pixel counter and enter the same size it shows up much bigger:

1579891154555.png

The pixel counter makes more sense since it's a 1080p camera (1080 pixels vertically, versus the 419 shown). I also can't enter the size values manually, which is annoying. Is there a fix for this or do I need to do trial and error until I get the pixel (but not visual) size I want? Thanks!
 
I think it's because of the varifocal lens. Someone with a true fixed lens camera should test it.
 
usaf_pride said:
Calibrate the camera. See this post.
Click to expand...

That's interesting, but I don't have the "Global Setup" tab with the calibration options and I don't see it mentioned in this model's manual:

1579973401267.png

Either way, if we were talking about object size in inches/feet/meters/whatever, calibration makes sense. The UI appears to only be talking about pixels, though that also seems to be the case for the post you linked to.
 
SkyLake said:
I think it's because of the varifocal lens. Someone with a true fixed lens camera should test it.
Click to expand...

You might be right, especially based on the calibration talk, though that would only make sense if the numbers in min/max size meant something other than pixels. Though come to think of it, the max size is a square 8191 "units" which if you convert proportionally to the pixels somewhat makes sense. But then in that case the pixel counter is almost meaningless if it's using some other units. Definitely confusing, though I think I'm trusting the min/max size a bit more now that I think they're not pixels.
 
Here are comparisons from a fixed lens HFW4231E-SE

target1.jpgtarget2.jpg
 
tigerwillow1 said:
Here are comparisons from a fixed lens HFW4231E-SE
Click to expand...

Thanks for checking. I really don't think there is a "fix" here like I originally thought; min/max is probably just another unit. If you can calibrate the camera then it becomes more accurate with varying distance, otherwise it's probably the same throughout the whole frame.
 
Until some better theory comes along I believe that the calibration is relevant only for the new human and/or vehicle detection features. Too bad questions like this can't be resolved by reading the manual.
 
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tigerwillow1 said:
Until some better theory comes along I believe that the calibration is relevant only for the new human and/or vehicle detection features. Too bad questions like this can't be resolved by reading the manual.
Click to expand...
I agree, drawing the max/min is really just guesswork.
 
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