To compose a painting, you must know something about perspective. In Western drawing and painting (oil painting, watercolour etc.) linear perspective is usually applied. Linear perspective is a geometric method of representing objects so that they appear three-dimensional.   

Perspective theory applied in Western painting presumes that all side edges of an object placed flat recede to vanishing points on the horizon line. If you put a piece of glass vertically in front of your eyes and draw what you see through the glass, you will achieve a picture with correct perspective. Understandably, in doing this, you cannot turn your head left or right, up or down. You have a fixed "focus". Your picture displays what your field of vision holds, the same as a photograph of the scene.

 This method is quite "precise". You can even mathematically work out the relative size of everything in a painting. However, it has advantages and limitations. The advantage is that it does help to create an illusion of depth on a flat surface (your painting) -- you can go deep into it. Its limitation is that it constrains your view to a small area that does not represent what you have seen and what is stored in your memory. After you visit a beautiful mountain, equipped with a camera, you get a whole picture of the mountain in your head, but your camera only gives partial views. All the photos you have taken during the trip are "true" to life but none of them is true to your impression.

Chinese artists treat this problem in their own way. Their representation is not limited to one field of vision. They put many views into one picture thus exhibiting the whole picture stored in the artist's memory. Such a painting often has several focus points. A Chinese landscape artist can depict what he sees at eye level, above and below that level, and what he sees as he turns his head to the right, left or even further round. This method is called "scattered-focus" perspective (sandian toushi), as opposed to the Western true perspective. A Chinese landscape may be a two or three-metre high vertical scroll or a dozen-metre long horizontal scroll, and as the viewer unrolls the painting, he feels he is travelling among mountains or along a fiver with the artist. He is reliving the artist's experience. While you can view an oil painting all at once, you must view a Chinese scroll painting section by section.

Chinese artists' perspective is not as "precise" as in the West. Artists in China follow a few rough guidelines: the farther away an object is, the smaller it is; the nearer an object is, the larger it is. Everything has three surfaces. Nevertheless, with these few guidelines, Chinese landscape artists create extensive, imposing and enthralling pictures of nature.