Interesting. For the benefit of those who cannot understand Chinese, or have difficulties, let me try to translate the document.
(below image 3)
Controlling the perspective of an image is simply controlling the size of the foreground and background in the picture.
Comparing image 1 and 2,
using packet drinks of similar size, "I" have taken the picture such that the packet on the right appears bigger.
Using packet drinks of similar size, "I" have taken the picture such that the packet at the centre appears smaller.
In this case, when there is an increase and decrease in the size of the object at the same time, there is a change in perspective.
This can only be achieved by a change in the distance between the object and you, and a change in the field of view.
(Image 4-6)
4. -> 5. The position in which the picture is taken is not changed, while the field of view is changed.
All three packet drinks increased in size at the same time, this means that the perspective is not changed.
(Image 7-8)
Now here's the main point.
From image 4, I had added another two packets.
Though in theory, image 7 and image 5 has the same perspective,
people tend to compare the sizes of different objects.
Thus, even though image 4 and 7 has the same perceptive, the [perspective feeling] is totally different.
*Correct me if I had translated anything wrongly.