Camera model_

1. Camera model

This section refers to : You know : Zhang Jiajie

The pinhole model we usually call is an extremely simplified model , Its simplified object is 「 A camera with a single thin lens 」, Its meaning is ： After an appropriate degree of approximation , A camera with a single thin lens as the lens , Its optical behavior is similar to that of a pinhole camera to some extent .
First look at thin lens imaging , I learned this in middle school , It can be roughly illustrated by the following figure :

For a thin lens , Its optical behavior is completely determined by four factors : optic axis , Light heart , Front focus （ Focus of matter ）, Posterior focus （ Like the square focus ）. In the diagram above , The optical axis is the horizontal dotted line in the figure , The optical center is O spot , The front focus is G spot , The back focus is C spot . As for why we need to treat the two focuses differently , It is because the media on both sides of the lens are different —— Although usually there is air on both sides of the lens . As long as these four elements are identified , Then the optical behavior of this thin lens is completely determined , For any point in space （ Of course, because of the symmetry of space , Let us assume that light travels from left to right , Any point in space in this sense , As 「 Source 」 From the point of view of ）, We can all find out in 「 Lens imaging 」 The corresponding image after this transformation . Starting from these four elements , We can define three special rays ：

1. Passing object point , A ray of light parallel to the optical axis , After it passes through the lens, it will shoot at the focus of the image ;
2. The light passing through the object point and the optical center , Its direction remains the same ;
3. The light passing through the object point and the object focus , After passing through the lens, it is parallel to the optical axis .

author ： Zhang Jiajie
link ：https://www.zhihu.com/question/23512027/answer/24832662
source ： You know
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