"field of view" measurement

Hi everybody,

I need to neasure the "field of view" of thermal and day camera. I have all the consumed test equipment, what the algorithm i need for measurement the FOV?

thank you, itai

Answer 1

[Image Analyst]

See my attached spatial calibration demo.

[Ian Chua]

Did this actually answer the question? What is meant by "field of view" of a camera? Suppose I want the camera to capture only a one metre square of area as the FOV of interest for sampling count purpose. If the camera is too near, the required FOV is too large for the camera. And if the camera is too far, the FOV could become quite small. On the other hand the camera has zoom function, so the magnification factor also needs to be taken into accunt. It seems the question is rather vague.

[Image Analyst]

I think it answers the question. He has an image from a camera, and asks what the field of view is. So you basically have to have something of known size in the scene. Then you can measure that known thing in pixels and, once you have that, you can get a spatial calibration factor in units of centimeters (or whatever real world units you're using) per pixel. So now whenever you measure something you can multiply by that factor to get distances in real world units instead of in pixels.

If you have a known field of view that you want, you can either put something in the field of view (like a meter stick) and move your camera toward or away from it until it fills the field of view. Or if you need to decide on a lens to get, there are mathematical equations you can plug parameters (like field of view and working distance) into to get the focal length of the lens you should buy. Your imaging vendor should be able to help you with that. Just tell them the camera you're using (because they need to know the sensor size), and your desired field of view, and your desired working distance (lens-to-scene distance) and they'll be able to tell you what lens to buy.

[Ian Chua]

Got it... looks like the FOVs are approached differently because of different applications. In my case, the FOV needs to be pre-determined beforehand in order to ascertain the appropriate distance between the camera and the plane containing the FOV. But interesting!