so most of the various cameras I'm dabbling with have a toggle for 3D Noise reduction on/off. the IR illuminated night video looks much smoother with it on, but zooming in on a face or whatever and it looks really bad and blotchy. current camera I'm playing with is a IPC-T2431T-AS-3.6mm bought from this site.
here's a still capture of a night motion detect from this cam. with me about 25 feet from the camera. video is in 15 fps, 1/60th shutter. 3D NR is OFF, video is highqest data rate and quality, with an i frame every 5 frames (3 per second)
It essentially smooths noise. Makes the overall image cleaner at the expense finer resolution and motion blur. You need some of it as turning it off will make for a real poor image. For general surveillance (people) I leave it set at about default. For LPR applications i turn it down to reduce motion blur.
That camera has only a 1/3” sensor. At 25’ and at that focal length that is as good as you are going to get I'm afraid. I'd leave it on and set at default so that when people walk closer in to the camera, you will get a much clearer capture. You could also increase the shutter to 1/100 or even 1/125. That will severely reduce (or totally remove) motion blur from people walking/running.
"3D" noise reduction is called "3D" because it utilizes previous exposure data to cancel out noise (basically like "image stacking" commonly done in astrophotography). It is highly effective on static scenes, but when things are in motion, some of the motion inevitably gets mistaken for noise, and incorrectly canceled out. It is worst when the thing moving has relatively low contrast from the background, because then the noise reduction error is more significant.
As @biggen said, at 25 ft with that camera you’re close to as good as you’re going to get without supplemental light. Even a single 100 watt light will help a lot. With a 3.6 lens and minimal external light 12-15ft will be closer to best facial ID image.
Generally I run DNR at about 30-40 at night and I prefer matching Iframe to FPS
As others have said, that is about as good as you will get with that camera.
To identify someone with the 3.6mm lens, someone would have to be within 20 feet of the camera, but realistically within about 12 feet at night after you dial it in to your settings.
My neighbor was bragging to me how he only needed his four 2.8mm fixed lens cams to see his entire property and the street and his whole backyard. His car was sitting in the driveway practically touching the garage door and his video quality was useless to ID the perp not even 10 feet away.
Since digital zoom only works on the TV and in movies, we need optical zoom. So you need another camera optically zoomed in to that pinch point if that is an area you want to cover.
I will say that I am still going in and tinkering with camera settings usually for night. Getting to that magic "sweet spot" of low noise, no motion blur and good images is a slow process for me as a button pusher. Some cameras seem to set up very quickly, but others can be a long process. That's true of the same model cameras, too, because of the different conditions they're "seeing" based on their specific location.
interestingly, it got a lot better when I cranked up the FPS/iframe ratio, currently its 3:1 (15 fps, 5 frames/iframe, so 3 iframes/second).
for those unfamiliar with the concept, MPEG, including mp4, has the concept of I, P, and B frames. an I frame is self contained, a p-frame is built on the prior I or P frame, and a B frame is based on the previous-and-next I/P/B frame (B for bidirectional). using more iframes requires a higher data rate but results in better stills taken from the video.
Please post a screenshot showing that you can set a 15FPS and 5 for an iframe. My Dahua cameras do not allow that.
I think you are misunderstanding what the camera is telling you. I have several different Dahua models and not one of them allows the iframe smaller than the FPS. If I change FPS to 20, then the minimum it allows is 20.
Do you have Blue Iris? If so post a screen shot of the cameras tab and what the KEY is. A key of 1.00 is an iframe every 1 second, so the FPS and iframes are identical.
If you are correct, yours would be an iframe of 3.00 - I suspect it is the other way and will be an iframe of 0.33 which means an iframe of 1 every 3 seconds.
So yes, if your FPS was 15 and the iframes were 45, then the static image may appear better, but it can suffer from motion detection issues and bad motion in some instances.
