The photogrammetric camera's field of view defines how much it sees and is a function of the focal length of the lens and the size (often called the format) of the digital sensor. For a given lens, a larger format sensor of photogrammetric camera has a larger field of view. Similarly, for a given size sensor, a shorter focal length lens has a wider field of view. The relationship between format size, lens focal length and field of view is shown below.
The standard photogrammetric camera lenses of available with V-STARS are so-called medium angle lenses and have about 50° wide fields of view. The wider the field of view, the more you see from a given location. For a medium angle lens, a convenient rule of thumb is that you will generally need to get back as far from the object as the size of the object. For example, you will get about three meters (ten feet) back to see a three-meter (ten foot) object. In general, there is a tradeoff between the field of view of a lens and accuracy. Although wider-angle lenses need less room around the object, they also tend to be less accurate. (The reasons for this are beyond the scope of this introduction.) Thus, you generally want to use the longest focal length lens you can. The medium angle lenses provided with V-STARS represent a good compromise between field of view and accuracy.
Posts
