In the category of visual art, the basic elements of sketch are light, color and shape. Here, without light, it is colorless, colorless and invisible, and the decisive factor is light; The most changeable intermediate link is color; The final result is the shape.

In the field of plastic arts, the basic elements of sketch are point, line and surface. This is the first viewpoint put forward by Kandinsky, a master of abstract painting. Because the sketch of structure sketch teaching AIDS in this unit mainly solves the problem of body structure, and basically does not consider the color problem, therefore, points, lines and surfaces are the main contents of our research.

Second, the basic principle of point, line and plane

1. Point with position, size and shape

The concepts or definitions of points, lines and surfaces in painting and geometry are not exactly the same. The key is that the concepts of points are different. In mathematics, a point has only position but no size and shape, while in sketch, a point has both position and size and shape.

2. Circular relationship of points, lines and surfaces

Because the points in the sketch have position, size and shape, it leads to the circular relationship among points, lines and faces in the sketch: points are facets; The surface is a big point; The line is a variable intermediate link. In sketch, the movement of points and faces can form lines; In a specific environment, a line can be regarded as both a point and a surface.

From this, we (painters) can say that the world is made up of points (such as pointillism and ink painting); The world is made up of lines (such as line drawing); The world is made up of facets (such as cubism); Of course, it can also be summarized as-the world is made up of points, lines and surfaces.

So, what is the most important thing? It depends on our needs:

Face-the first impression of the viewer;

Line-the most dynamic expression;

Point-the key to grasp and locate.

3. Point-line-surface constraint relation

Everything starts from one point, and the point determines the position and size of the shape; A line is a collection or trajectory of points; A surface is a collection or trajectory of lines. Therefore, in the sketch, there is a saying that the line is taken and the line is taken as the surface.

Third, related concepts and methods

"Extreme point"-the highest, lowest, leftmost and rightmost extreme point of a shape (similar to the point in "node editing" in computer painting).

In the primary stage of sketch, the key to quickly draw the basic shape of an object is to be sensitive and grasp the "extreme point".

"Triangulation"-a method of determining extreme points with triangles.

"Triangulation" is a drawing method initiated by teachers in our college. This method was gradually formed in the process of using teaching AIDS in structure sketch. Its main basis is: triangle is the simplest and easiest shape to grasp; All three sides of a triangle have definite angles and directions.

"Positioning line"-a straight line with definite extreme points.

The so-called "positioning line" is actually a line segment with endpoints, which is different from the general line segment, that is, the "positioning line" must be "written" (not drawn with a ruler or repeatedly). The main content of "positioning line" training is to ask students to connect two endpoints (or extreme points) with a straight line. There are three ways to draw "positioning line": one is to draw by the movement of knuckles, and the drawn straight line is short; The other is mainly drawn by the movement of the wrist joint, and the length of the straight line can be greater than the first one; Another is done by the movement of elbow joint and shoulder joint, so that the straight line can be long or short. We ask students to practice drawing a long "positioning line" mainly through the movement of elbow joint and shoulder joint. On the one hand, the purpose of doing this is to "open" the new students' shoulder joints and correct their long-standing bad habit of drawing small pictures only with their knuckles and wrists; On the other hand, it is also to meet the needs of structure sketch's teaching aid sketching and the use of long lines in the next unit's sketching.