I picked up a 2.8mm fixed-lens Hikvision from Andy to try out.
Hikvision's infos: 8 MP Outdoor IR Fixed Network Turret Camera
Andy's listing: US $150.0 5% OFF|2019 Latest New 8MP IPC T2385G I IR Fixed Lens Turret POE Network Camera IP67,Free DHL shipping on AliExpress - 11.11_Double 11_Singles' Day
Dahua's overview:
I gave it the mailbox job, in place of a Dahua IPC-HDW2231R-ZS, which had been zoomed as wide as possible at 2.8mm. So it doubles the pixel density (2160 pixels vertically).
Initial impression I fired it up and got accustomed to Hik's menu system, since this is my first Hikvision cam. One of my first discoveries was that it has no AUTO shutter mode. I can set separate day and night profiles, but it's up to me to specify a shutter speed for each. Ordinarily I would either set daytime shutter to AUTO, or specify a range of shutter speeds like on a Dahua in Manual exposure mode. Edit: per alastairstevenson I may be misunderstanding this setting. The specified shutter may just be the slowest setting allowed. After some experimentation, I think he's right. I set the exposure to 1/3 second in full sunlight and it did not turn into a whiteout scene, so I think the chosen shutter speed is simply a lower limit.
Daytime performance With twice the pixel density, face identification range is boosted as expected. I played with the configuration and found that fine detail is highest with no Backlight compensation (as opposed to using WDR or HLC to brighten up the dark areas), but the downside is that highlights from direct sunlight blow away detail too. I haven't found any other alternative in the form of Gain, Exposure, or the Brightness and Contrast settings. There's no Gamma adjustment like a Dahua would have, or that probably would have been a good option.
I also tried several bitrate settings. With Constant bitrate mode, passing cars are followed by visible artifact trails at lower bitrates, so I recommend the highest bitrate of 16Mbit/sec or else use Variable bitrate and Highest quality.
Here's a video showing how the scene reacts to various Backlight compensation settings, shutter-speed settings, Gain, and Brightness/Contrast. The focus of most of the video is a car with sunlight overexposing the hood.
1:00 into the video shows how HLC has brought out detail in the highly-exposed area, but also muted the detail in some pavement beyond the car.
1:45 into the video I swap to medium WDR, same effect. You can see the rib on the car's hood, and the little shark-fin things on the left and right edges of the hood, but some detail is lost.
2:40 into the video I reduce Brightness and Contrast to zero in an effort to bring out the hood details without using Backlight compensations. The rest of the scene suffers; it's not really a solution.
3:00 I try reducing Gain, then setting shutter speed to 1/10000th, to see if the overexposure can be addressed that way (no), then 1/250th for contrast, then back to 1/1000th
I tried moving the sun to the other side of the planet, but there's some kind of security lockdown on it, so I'm afraid I'm stuck with the sunlight coming from that direction. I'll play around with the HLC versus no-HLC option and see which one is the best compromise for this scene. For $150 for an 8MP camera, I'm not expecting miracles.
Edit: here are some shots of me standing still in front of the backlit car, including a crop showing HLC off versus on. As you can see, it's a trade-off.
Hikvision's infos: 8 MP Outdoor IR Fixed Network Turret Camera
Andy's listing: US $150.0 5% OFF|2019 Latest New 8MP IPC T2385G I IR Fixed Lens Turret POE Network Camera IP67,Free DHL shipping on AliExpress - 11.11_Double 11_Singles' Day
Dahua's overview:
I gave it the mailbox job, in place of a Dahua IPC-HDW2231R-ZS, which had been zoomed as wide as possible at 2.8mm. So it doubles the pixel density (2160 pixels vertically).
Initial impression I fired it up and got accustomed to Hik's menu system, since this is my first Hikvision cam. One of my first discoveries was that it has no AUTO shutter mode. I can set separate day and night profiles, but it's up to me to specify a shutter speed for each. Ordinarily I would either set daytime shutter to AUTO, or specify a range of shutter speeds like on a Dahua in Manual exposure mode. Edit: per alastairstevenson I may be misunderstanding this setting. The specified shutter may just be the slowest setting allowed. After some experimentation, I think he's right. I set the exposure to 1/3 second in full sunlight and it did not turn into a whiteout scene, so I think the chosen shutter speed is simply a lower limit.
Daytime performance With twice the pixel density, face identification range is boosted as expected. I played with the configuration and found that fine detail is highest with no Backlight compensation (as opposed to using WDR or HLC to brighten up the dark areas), but the downside is that highlights from direct sunlight blow away detail too. I haven't found any other alternative in the form of Gain, Exposure, or the Brightness and Contrast settings. There's no Gamma adjustment like a Dahua would have, or that probably would have been a good option.
I also tried several bitrate settings. With Constant bitrate mode, passing cars are followed by visible artifact trails at lower bitrates, so I recommend the highest bitrate of 16Mbit/sec or else use Variable bitrate and Highest quality.
Here's a video showing how the scene reacts to various Backlight compensation settings, shutter-speed settings, Gain, and Brightness/Contrast. The focus of most of the video is a car with sunlight overexposing the hood.
1:00 into the video shows how HLC has brought out detail in the highly-exposed area, but also muted the detail in some pavement beyond the car.
1:45 into the video I swap to medium WDR, same effect. You can see the rib on the car's hood, and the little shark-fin things on the left and right edges of the hood, but some detail is lost.
2:40 into the video I reduce Brightness and Contrast to zero in an effort to bring out the hood details without using Backlight compensations. The rest of the scene suffers; it's not really a solution.
3:00 I try reducing Gain, then setting shutter speed to 1/10000th, to see if the overexposure can be addressed that way (no), then 1/250th for contrast, then back to 1/1000th
I tried moving the sun to the other side of the planet, but there's some kind of security lockdown on it, so I'm afraid I'm stuck with the sunlight coming from that direction. I'll play around with the HLC versus no-HLC option and see which one is the best compromise for this scene. For $150 for an 8MP camera, I'm not expecting miracles.
Edit: here are some shots of me standing still in front of the backlit car, including a crop showing HLC off versus on. As you can see, it's a trade-off.
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