Re: Measuring angles in an image.


"Geobird" <a1chandan@xxxxxxxxx> wrote in message
news:d34d04a4-fe76-4366-b06c-5889f5d725a1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Given that you have the distance from camera to the centre of the
image you are going to capture ( principle point) , is it possible to
measure the angle subtended by any element on the image with respect
to camera axis.
Depends entirely on the lens. You can probably work it out from the lens
specification, but the simplest method is set up a reference grid/ruler at
(say) 1m, set the lens to focus at infinity and see how many pixels the lens
subtends. This is OK with a single focus lens, you'd need to do multiple
measurements for different settings on a zoom lens.

After this "calibration" process, its simple to work out the angular
relationship of the image center pixel with any other pixel.

--
regards,
Stewart DIBBS
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