DORI Specs

[qflyer]

Trying to better understand DORI numbers. Is there an actual standard that's used across the industry, or is it up to the camera manufacturer to set the standards for testing, thus making DORI not much more than a marketing device?

For example, below are two different cameras from two companies. Looking at the specs, the hikvision seems like it would be a better camera than the Dahua (except for night vision based on sensor size), yet the Dahua claims better DORI specs. If the DORI standard used is the same between the two companies, what makes the Dahua DORI numbers better than the Hikvision? Megapixels? Isn't the mantra around here that megapixels are one of the least important factors when picking a camera?

Hikvision DS-2DF8236IX-AEL
MP: 2
Image sensor 1/1.8
Focal length: 5.7 mm to 205.2 mm
Horizontal FOV: 59.8° to 2.0°
Vertical FOV: 33.6° to 1.1°
Identify: 215.5 m (706.9 ft)
Recognize: 430.9 m (1413.8 ft)


Dahua DH-SD5A445XA-HNR
MP: 4
Image sensor: 1/2.8
Focal length: 3.95 mm to 177.7 mm
Horizontal FOV: 70.3°–1.8°
Vertical FOV: 37°–1°
Identify: 317 m (1040.03 ft)
Recognize: 635 m (2083.33 ft)

Hikvision is priced somewhere around 2X more than the Dahua, so what am I getting for twice the money (besides worse DORI specs)?

 

[wittaj]

There is no real standard unfortunately, and in theory more MP means better DORI numbers. This is why so many have come here after purchasing the 4K/X and upset that they cannot identify at 40 feet out per the DORI specs. It is a great camera, but 40 feet is too much of a stretch to IDENTIFY a stranger on a 2.8mm lens regardless of MP. These sensors are still too small.

In real world situations, most of us have found that you would cut DORI in half or so, and even more at night. You will not identify a stranger at 1,000 feet.

The Hik provides a much further zoom (higher focal length) and is a better MP/sensor ratio.

 

[qflyer]

There is no real standard unfortunately, and in theory more MP means better DORI numbers.

In real world situations, most of us have found that you would cut DORI in half or so, and even more at night. You will not identify a stranger at 1,000 feet.

The Hik provides a much further zoom (higher focal length) and is a better MP/sensor ratio.

Yeah, that's kinda what I was afraid of, so it boils down to marketing. So hikvision needs to step up their marketing game, because they have a better camera than the Dahua, it's priced higher, but if I'm basing my choice on just being able to see my front gate 1,000' away, I'd end up buying the Dahua even though the Hik is in reality the better camera.

Follow-up question regarding megapixels: does the monitor I view the footage on make a difference? Say I have a 4K camera, but viewing on a 1080 monitor. Will the effective DORI specs of a 4K camera be more in line with a 2MP camera since it's limited by the monitor? If I never intend to buy a 4K monitor, is there any reason to buy 4K cameras?

 

[sebastiantombs]

It would help if we knew what you're trying todo with the camera. Distance to the target, lighting at night and proposed mounting height all combine to determine DORI capability. Digital zoom on a monitor, be it 1080 or 4K is a limited feature. What you are actually doing with digital zoom is magnifying the existing information. At some point the pixels start to appear as blocks and all detail is lost.

The bottom line with cameras is to chase sensor size over resolution. A 4K camera with the same sensor size as a 2K camera will need roughly double the amount of light to be able to see as well as a 2K at night. This happens because the available light is spread across twice as many pixels in the 4K camera. During the day a 4K will look better even on a 1080 monitor.

 

[qflyer]

It would help if we knew what you're trying todo with the camera. Distance to the target, lighting at night and proposed mounting height all combine to determine DORI capability. Digital zoom on a monitor, be it 1080 or 4K is a limited feature. What you are actually doing with digital zoom is magnifying the existing information. At some point the pixels start to appear as blocks and all detail is lost.

Yeah, I started out with a 49225 PTZ for keeping up with any unwelcomed visitors to my boat dock. As I've added more cameras to the dock itself, I don't really need the PTZ for dock security anymore. I'm going to move it up to my house to keep an eye on the driveway/house/storage buildings/etc. I'm happy with the 49225 because it has a great clarity day and night and everything I want to view is within 200-300' of where I'll put the camera.

I do want to put another PTZ at the lake and I'm mostly looking for image clarity and longer viewing distances than I got with the 49225. I'm only interested in day time performance, night time isn't an issue at all. So with that said, I see "identify" specs from Dahua up to about 1500' depending on camera model, and Hikvisions that have better specs and much higher prices with lower DORI numbers.

I just want to make sure that I'm not buying a lesser quality camera based on inflated DORI specs, which is what I feel like I'd be doing if I went with Dahua over Hikvision, per the two cameras listed above. But if the 4MP vs 2MP difference between the cameras is really that big of a DORI game changer, then the Dahua wins despite shorter focal length and smaller image sensor and lower price.

 

[wittaj]

Under ideal conditions (perfect sun, object not moving, etc) you may get a little better quality with a higher MP camera, but these sensors are so tiny that I would favor one with the best MP/sensor combination.

I have both the 49225 and 49425 and if I showed you a shot from 500 feet out of the same object, most couldn't tell the difference between 2MP and 4MP. At 30 feet out or so yeah you can probably tell.

 

[mat200]

Trying to better understand DORI numbers. Is there an actual standard that's used across the industry, or is it up to the camera manufacturer to set the standards for testing, thus making DORI not much more than a marketing device?

For example, below are two different cameras from two companies. Looking at the specs, the hikvision seems like it would be a better camera than the Dahua (except for night vision based on sensor size), yet the Dahua claims better DORI specs. If the DORI standard used is the same between the two companies, what makes the Dahua DORI numbers better than the Hikvision? Megapixels? Isn't the mantra around here that megapixels are one of the least important factors when picking a camera?

Hikvision DS-2DF8236IX-AEL
MP: 2
Image sensor 1/1.8
Focal length: 5.7 mm to 205.2 mm
Horizontal FOV: 59.8° to 2.0°
Vertical FOV: 33.6° to 1.1°
Identify: 215.5 m (706.9 ft)
Recognize: 430.9 m (1413.8 ft)


Dahua DH-SD5A445XA-HNR
MP: 4
Image sensor: 1/2.8
Focal length: 3.95 mm to 177.7 mm
Horizontal FOV: 70.3°–1.8°
Vertical FOV: 37°–1°
Identify: 317 m (1040.03 ft)
Recognize: 635 m (2083.33 ft)

Hikvision is priced somewhere around 2X more than the Dahua, so what am I getting for twice the money (besides worse DORI specs)?

Hi @qflyer

Please see the DORI section of the cliff notes, and feel free to ask questions ..

basically, the vendors post more optimistic numbers than what many of us like to see - and are based on 80 ppf pixel density and a straight on facial ID image capture .. imho this is too optimistic thus many of us use 100 ppf for the calculations ( see the equation in the DORI section of the cliff notes )

Also those DORI calculations are based on good lighting conditions and effective image capture in terms of meaningful quality and quantity in terms of pixels of image.