PTZs vs. megapixel cameras

[jhonovich 0]

I am trying to think through the tradeoff between using megapixel cameras and PTZs.

 

It's obvious from using them that a 23x analog mechanical PTZ can zoom in far greater than even a 16 megapixel camera. I have tested this and while the megapixel camera is incredibly impressive for a fixed camera, it did not come close to the level of zoom possible in a 23x analog PTZ (now, i know there are important tradeoffs like a megapixel's ability to record the whole area).

 

My calculation is that a 16 MP camera offers the equivalent of a traditional 8x PTZ camera, far less than a 23x PTZ. I came to this by multiplying the traditional resolution of an analog camera (640 x 480) by 8 which approximately equaled 4872 x 3248 imager (the resolution of Avigilon's 16 MP camera).

 

1. Can someone carefully look at these calculations and tell me if I have made an error? I don't want to base a theory on flawed math.

 

2. How are you deciding on when to use megapixel versus PTZs?

Edited May 26, 2008 by Guest

[thewireguys 3]

The problem with PTZs is they can only look in one direction at a time. If i was doing a money no object install I would use Megapixels and PTZs. You could get detailed overall image and be able to zoom in with the PTZ.

 

I think PTZs are better if someone is monitoring the system. Megapixels are better when the system is just for recording.

 

If I remember correctly Avigilon's 16MP is around $9000.00 without the SLK lens.

 

 

I wonder when the first Megapixel PTZ camera is going to be released?

[jhonovich 0]

Cieffe has a 2 megapixel PTZ.

 

'I think PTZs are better if someone is monitoring the system. Megapixels are better when the system is just for recording."

 

I might modify that statement: Megapixel is better when the system is just recording or when the area you want to monitor is not very deep. PTZs are better when the area for live monitoring is deep.

 

By deep, I mean how far from the camera do you need to monitor. Do you need to see something 100 feet away or 300 feet away.

 

For instance if a 16 MP camera has an effective 8x zoom relative to a traditional PTZ, if you need to identify a person 80 feet away from the camera, this should work even in a live monitoring situation. However, if you need to monitor a person 250 feet away, the 23x mechanical PTZ will work but the megapixel will not.

 

I calculate that a 23x analog PTZ can see about 3x farther than even a 16 MP camera. Say the analog PTZ has a focal length range of 3.6~82.8 mm. A 16 MP camera could provide an equivalent focal length range of 3.6~28.8. The PTZ would have a maximum focal length almost 3x longer than the 16 MP camera.

 

I hear a lot of discussion on replacing PTZs with megapixel but it looks like the depth of area you are covering is a major consideration in making this decision.

 

Can someone please review my numbers?

 

Any thoughts on the tradeoffs?

[robert 0]

I wonder when the first Megapixel PTZ camera is going to be released?

 

Here we go, Axis do have some.

 

 

Also:

http://www.cieffe.com/products/cameras/IP/nettuno_megadome

[jhonovich 0]

I wonder when the first Megapixel PTZ camera is going to be released?

 

Here we go, Axis do have some.

 

 

Also:

http://www.cieffe.com/products/cameras/IP/nettuno_megadome

 

Are you sure those are megapixel cameras? Those Axis cameras look standard definition.

[robert 0]

I`m confused now

 

 

How to understand this ?

[jhonovich 0]

Hi Robert,

 

It's fairly common for camera manufacturers to use larger image sensors but lower resolution. They bin or downsample the image from say 3mp to 4CIF. Doing so can improve image quality. Or at least that is my understanding.

 

Best,

 

John

[robert 0]

Sounds like a marketing trick

Never installed these, just remembered that I have seen Axis PTZ`s on their website.

[thewireguys 3]

Sorry I should clarify my self I was talking about a traditional PTZ camera that has a Megapixel image sensor.

 

The Axis 212 is not a traditional PTZ camera. It has a very wide angle 3 megapixel lens and it allows you digitally PTZ the image with D1 resolution.

The camera not really a megapixel camera in the normal way you would think.

 

Axis 212 demo