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Line Crossing with Face Capture?

benm

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Hi all
I have a newly installed DS-7608 NVR and 2x 2CD238G2 cameras.
I would like Hik-Connect notifications so have set up line crossing on my driveway. I would really like to set up facial recognition so that me or a couple of other people don’t set off the line crossing alarm.

I’ve read that if you enable face capture on the camera then it turns off all the other alarms. Plus I’m not sure what face capture is and how it compares to ‘face comparison’, another term I’ve read

Is this possible? To set up a region or line to monitor but only alarm when face isn’t recognised with these models?

Many thanks in advance
 
You'll not be able to do that with your setup unfortunately. Firstly as you've mentioned correctly, you have to chose between Smart Events and Face capture - you cannot have both working together. Secondly, if you could have the two working together, it's Face Capture the camera has rather than Face Recognition, so when the camera detects the face of the toe rag stealing your car, it would disable the detection!
 
Ok thanks. So basically there is no way to do this and just ignore your own events!
Another question please!
I have a 4mm lens version to monitor a garage in a block quite some distance away. It pinged today but was very pixelated when I zoomed in during playback.
What is the optimum bitrate and fps I should set for further distance please?
 
Ok thanks. So basically there is no way to do this and just ignore your own events!
Another question please!
I have a 4mm lens version to monitor a garage in a block quite some distance away. It pinged today but was very pixelated when I zoomed in during playback.
What is the optimum bitrate and fps I should set for further distance please?
To be honest if it's some distance away you would be better with a narrower angle lens. 4mm is very wide at 87 degrees horizontal field of view. The screenshot below shows the DORI distances for that camera and lens:

Screenshot 2021-10-09 at 19.34.53.png


DORI is Detect, Observe, Recognise, Identify and the distances quoted are the maximum distance from the camera at which the pixel density is sufficient to Detect, Observe, Recognise, Identify a person. First look at the distance and see if it's achievable. What you can't do with a 4mm lens you may be able to do with a 6mm or maybe a 2.8 - 12mm adjusted to the narrow end.

Frames per second will have no effect on the image quality per-say. However as the bit rate is set in kilobits per second and the frame rate is in frames per second, it's important to not use a frame rate too high for the bit rate set. The local NVR menu gives a recommended bit rate according to the frame rate and compression level (quality) that you set, however those figures are for H264 compression and it's advisable to use H265. The law of diminishing returns applies and you'll be unlikely to see a visible improvement by cranking up the bit rate to the max. I use the attached table as a guideline and add 20 - 30% to the figures while setting the quality to higher.

One other thing to note is where you're playing back the video and also "zooming in". Playback will be clearest locally on the connected monitor as opposed to across the internet on your phone via HikConnect. As the camera is fixed lens, you can only "zoom" to the native image resolution before you start magnifying pixels and the image becomes blocky.
 

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To be honest if it's some distance away you would be better with a narrower angle lens. 4mm is very wide at 87 degrees horizontal field of view. The screenshot below shows the DORI distances for that camera and lens:

View attachment 6776


DORI is Detect, Observe, Recognise, Identify and the distances quoted are the maximum distance from the camera at which the pixel density is sufficient to Detect, Observe, Recognise, Identify a person. First look at the distance and see if it's achievable. What you can't do with a 4mm lens you may be able to do with a 6mm or maybe a 2.8 - 12mm adjusted to the narrow end.

Frames per second will have no effect on the image quality per-say. However as the bit rate is set in kilobits per second and the frame rate is in frames per second, it's important to not use a frame rate too high for the bit rate set. The local NVR menu gives a recommended bit rate according to the frame rate and compression level (quality) that you set, however those figures are for H264 compression and it's advisable to use H265. The law of diminishing returns applies and you'll be unlikely to see a visible improvement by cranking up the bit rate to the max. I use the attached table as a guideline and add 20 - 30% to the figures while setting the quality to higher.

One other thing to note is where you're playing back the video and also "zooming in". Playback will be clearest locally on the connected monitor as opposed to across the internet on your phone via HikConnect. As the camera is fixed lens, you can only "zoom" to the native image resolution before you start magnifying pixels and the image becomes blocky.
Thanks for the advice. It’s strange as I asked on this forum before buying and was advised to go for a 4mm over a 2.8mm to achieve the distance?
I’ll look at the table and see if there’s any adjustments I can make
 
Thanks for the advice. It’s strange as I asked on this forum before buying and was advised to go for a 4mm over a 2.8mm to achieve the distance?
I’ll look at the table and see if there’s any adjustments I can make
That was correct - 4mm has a wide angle of 87 degrees, whereas the 2.8mm is ultra wide at around 105 or 107 degrees. The wider the angle (shorter focal length lens), the smaller distant objects will appear and the perspective (separation between objects) increases. The narrower the viewing angle (longer focal length lens, the larger distant objects will appear and the perspective decreases.

You don't mention how far away from the camera this garage is, so it's not obvious what focal length you would need to see it large enough in the frame to resolve the detail you want in the captured image. A camera model with a varifocal 2.8mm - 12mm lens would allow you to choose anywhere between ultra wide 108 degree (2.8mm) and a much narrower 45 degree field of view (12mm) to optically zoom in toward the garage. I should mention that you could also get a fixed lens 6mm model which would give a horizontal field of view of 51 degrees.

Edit: I'm not actually sure I trust those horizontal viewing angle figures which come directly from the data sheets. I find it hard to believe that the 6mm fixed lens is 51 degrees horizontal while the 12mm end of the vari-focal only differs by 6 degrees. Both cameras feature the same 8MP 1/1.8" sensor.
 
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Hi,
Not the greatest pic i'm sorry about that. However, should show you how far away.
I've already got the 4mm fitted and in use, so i am stuck with it. So i thought i would ask about what the best quality settings are for a longer distance?
img_6157-002-jpg.5568
 
Hi,
Not the greatest pic i'm sorry about that. However, should show you how far away.
I've already got the 4mm fitted and in use, so i am stuck with it. So i thought i would ask about what the best quality settings are for a longer distance?
img_6157-002-jpg.5568
There are no better quality settings for distance - the image settings would be the same regardless. To give a better idea of the distance, take and share a snapshot directly from the HikConnect app as that will give the view as seen from the camera and allow a guesstimate of the percentage of screen view that the garage occupies. It will however only confirm whether or not you have the right camera for the job.
 
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