Fisheye camera false advertising

[Javik]

I am getting really annoyed looking at fisheye camera specifications. The amount of bullshit in the fisheye camera industry is piling up, and I'm getting tired of shoveling through it.


If you have a perfectly circular lens view on a rectangular sensor, you should not claim the full sensor resolution as the usable resolution. But that is what many companies are doing.

Hikvision DS-2CD6362F-I 6MP IR Panaramic 180/360 Degree, Indoor
Max resolution: 3072 x 2048
360 degree view.
Actual resolution is the radius of the circle squared times pi
1024 (y axis radius) squared (1048576) times pi = 3294198 actual (3.3MP)

Usable pixel coverage is 52%. (What a waste of an HD rectangular image sensor.)



The only time your fisheye resolution is really better than this is when the view is not perfectly circular, either due to oval lens optics or because the circular view overlaps the edges of the sensor.

Hikvision DS-2CD2942F-IS 4Mp Indoor D/N Network Fisheye Camera
Max resolution: 4 megapixel (2560 x 1440)
Angle of view: 186°(horizontal), 106°(vertical)

Caculating pixel coverage of that was quite a pain but it is about 81.97% sensor coverage, not including the reflected / blur zone around the edge.

http://www.regentsprep.org/regents/math/geometry/gp16/circlesectors.htm
http://www.blocklayer.com/protractor-printeng.aspx

2560 * 1440 = 3686400 * 81.97% = 3021742 (3.0 MP)

.... so:
- the "4MP" fisheye is really 3.0 MP usable, with a long rectangular view
- the "6MP" circular fisheye is really 3.3 MP usable, or just 9% higher detail

 

[jaclarkaus]

They are not the only ones ...

A '35mm' or 'full frame' camera has a sensor that is 35mm wide.

So you'd imagine a 1" or 1/1.16" or 1/2.3" sensor would have one that wide? Wouldn't you?

Well, they are not. A 1" or 1/1.16" or 1/2.3" sensor is calculated by adding the width AND the height together ... makes them lots smaller (a 35mm would be 35 + 25 = 60mm or 2.36")

 

[Abbell]

Hehe, I remember back when I was installing hidden cameras for a gas station owner... he wanted fisheye lenses. I talked him out of it. I enjoy the further justification. Thank you!

 

[Javik]

Continued research.

Vivotek FE8191 12 Megapixel Fisheye Fixed Dome Network Camera
Sensor resolution: 4072x3046
Specified maximum resolution: 2944x2944

Actual circular resolution (1472 ^ 2 * pi) = 6807152 pixels

To which I say, WHAT THE F$%&, you mean this camera, sold as "12 MEGAPIXEL" is really only 6.8 megapixel???

God damn, the sales lying gets ridiculous as the megapixels go up.

Though the actual pixel coverage vs sensor resolution of this camera is pretty much the same as the example in my first post, for 6MP Hikvision.

4072x3046 = 12403312 pixels
6807152 / 12403312 = 54% actual usage of total sensor area

 

[Javik]

I see that for the more quality line products, they aren't doing the same amount of lying, and the numbers are more realistic.

Panasonic 360-degree Vandal Resistant Dome 9 megapixel Network Camera, WV-SFV481

9M Fisheye mode: 2992×2992 @ 15 FPS
Effective pixels: Approx. 12.4 megapixels

So Panasonic is using a 12.4 MP sensor but they are not claiming that is the actual fisheye camera resolution. Wow, some honesty in the numbers is quite refreshing.


But as I've mentioned, a square resolution still isn't accurate because the corner pixels around the circular fisheye see only black, and are useless. So Panasonic's "9MP" fisheye is still really more like 7 MP. So there is still some fibbing here, but nowhere near as bad as the cheaper brands.

(radius of circle squared times pi)
1496 ^ 2 * pi = 7030934 pixels

Is there any camera manufacturer that is willing to actually sell on the honest actual circular resolution of the fisheye, low as this real number may be? :nuts:

 

[nayr]

thanks for making these comparisons for us, but dont know why your so angry.. the sensors are up to spec, so the advertising is true.. the optics throw everything off for real world use but thats common for most things.. HDD's not providing advertised space, WiFi not providing advertised speed.. specs are true, but its all the overhead thats not disclosed upfront, yes thats shit and feels like your being deceived with marketing trickery, that does not make the specifications false.

this is just raw sensor advertisements, if they were advertising that it provided a 4MP image it would be false.. they are just claiming its a 4MP camera, which is technically true.

But calculating actual real world pixels is not easy or obvious to people, so your doing a good service by going about and figuring out the real fisheye image outputs.. it does feel like the market is taking advantage of fisheye buyers knowing they need a ton of MP, but a smart consumer like you know's what's really going on.

 

[Javik]

I am probably going to end up compiling a spreadsheet and posting it somewhere.