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digital PTZ - what is it? how?
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| robert |
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Posts: 184
Joined: 08 Dec 2007
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Posted: Mon Dec 08, 2008 12:00 pm
Post subject: digital PTZ - what is it? how?
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"Axis camera also features a built-in electronic PTZ (pan/tilt/zoom) function"
I still cant understand - if you dont have mechanical parts, how can you pan/tilt? Can anybody explain please.
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| Soundy |
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Posts: 898
Joined: 23 Feb 2006
Location: The Burbs of Vancouver
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Posted: Mon Dec 08, 2008 12:18 pm
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Most IP cameras do something like this... means that it lets you digitally zoom in on a portion of the total recorded image. Basically it just crops a small area of the picture and expands it to fill the original full frame (the "zoom" part), and then lets you move the crop area around (the "pan/tilt" part).
For example, take a look at this 1.3MP (1280x1024) original (NOTE: I've drastically increased the JPEG compression on these images to keep the sizes down, but the quality will suffer somewhat):
Now this is a 640x512 crop, resized to 1280x1024, which is effectively a 2X zoom factor:
And this is a 320x256 crop of a different area, again resized to 1280x1024, which makes it look like a 4X zoom.
When you're doing in in-camera, the software allows you to adjust the crop amount and move the cropped area around in real-time, thus simulating "PTZ" functionality.
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| robert |
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Posts: 184
Joined: 08 Dec 2007
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Posted: Mon Dec 08, 2008 12:23 pm
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You are star - thanks.
But they could have called it just - digital zoom, otherwise it sounds a bit misleading as there is no Pan or Tilt function, just a zoom. PTZ means you can rotate camera around.
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| Soundy |
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Posts: 898
Joined: 23 Feb 2006
Location: The Burbs of Vancouver
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Posted: Mon Dec 08, 2008 12:27 pm
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The term "digital zoom" is used more often with point-and-shoot digital cameras, and is generally regarded as little more than marketing BS, as you can do the same job in software later, usually with better results. It's also usually limited to the center area of the frame.
This would probably be better termed "simulated PTZ", since it's not JUST zoom.
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LPS Loss Prevention Systems - Maple Ridge, BC
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| kensplace |
Moderator
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Posts: 1036
Joined: 30 May 2006
Location: UK
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Posted: Mon Dec 08, 2008 11:30 pm
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You can get some cameras, that record a fisheye view (180 or 360 degree lens) that then use software to allow you to view different areas of the footage on playback. Its like being able to pan/tilt after the event has happened.
IPIX commandview is the only one I have tried, there are quite a few (more modern probably) on the market. Not cheap though.
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| Soundy |
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Posts: 898
Joined: 23 Feb 2006
Location: The Burbs of Vancouver
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Posted: Tue Dec 09, 2008 12:56 am
Post subject:
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The Capture OmniScape is another... same basic principle, just using a really wide fisheye lens.
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LPS Loss Prevention Systems - Maple Ridge, BC
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(='.'=)This is Bunny. Copy and paste bunny into your
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