1, shape

Form is the external form of objective image in space. Any object is different from other objects because of its specific physical existence. Form belongs to the basic basis and constant factor of sketch modeling. When we observe an object image, we should first pay attention to its basic shape as a whole. The basic shape of the object image is different, so the physical characteristics of the object image will be different. The basic shape is the relationship between an object and an image. Grasp the basic shape of an object, and then grasp its physical characteristics. Accurately grasping the physical characteristics of object images will lay the foundation for sketch modeling.

2. Structure

The structure in sketch mainly refers to the internal structure and combination relationship of objects. Form and structure are the relationship between appearance and connotation. Structure is the internal basis for the formation of foreign trade of objects. Without understanding it, it is impossible to accurately grasp a series of external characteristics of objects. In sketch, structure includes two aspects: one is anatomical structure or constituent structure; The second is the physical structure. The anatomical relationship between human body and animal bones and muscles is anatomical structure. Familiarity with anatomy is the basis of role modeling. The internal composition frame of other objects and its composition relationship are called composition structure, which is the internal foundation of similar objects. Grasping the structural relationship of objects in painting mainly lies in reflecting their basic physical characteristics by surface, which is convenient for understanding and grasping the complex structural relationship and is conducive to shaping the image volume.

3. Proportion

Modeling factors such as the structure and shape of objects are bound to be related to a certain scale in appearance, and different scale relationships are proportional. The forms of any object are connected according to a certain proportion. If the scale changes, the shape of the object image will be marginal. The observation of human body proportion in sketch should not be a mechanical and rigid comparison, but should pay attention to the proportional relationship of three-dimensional object image in a certain angle and perspective change. In comparison, we should pay attention to the proportion of objects and images, especially the proportion of large images and whole images, and should not stay in the proportion of local details. Beginners can get the accuracy of the basic proportion by means of tool measurement. With the improvement of observation ability, we should gradually abandon this method and pay attention to training the accuracy of observation ability through the comparison of feeling and vision.

4. Vision

The spatial phenomenon that the natural objects you see are nearly large and far small is the perspective phenomenon. Using scientific principles and methods, the perspective phenomenon is accurately shown on the screen, and its image, position and space feel are the same as the real scene, which is painting perspective. In sketch, the application of perspective is to determine the depth of the object on the picture, that is, the spatial position of the object and its parts in the picture, which is the basic factor to express the three-dimensional effect of the object and create the spatial effect in painting. Therefore, the perspective rule is an important basis for realistic modeling, and mastering the basic principles of perspective is the basis for accurately observing and truly depicting the spatial relationship between objects and images.

5. It is the main form of sketch-light and shade.

Light and shade is one of the basic elements of sketch, and it is also an important factor to describe the stereoscopic and spatial sense of objects and images. Any object will show a certain relationship between light and shade under the irradiation of light. The intensity of the light source, the distance from the light source and the different illumination angles will make the image of the object show different brightness. Light and shade are not only the three-dimensional sense of the image, but also the main factor to show the overall spatial effect in the picture. The treatment of light and dark levels and the contrast between reality and reality are the basic means to express the spatial relationship and the overall atmosphere.

Three areas of sketch: light, gray and dark. When the light shines directly on the object, there will be such a relationship, and these three areas will naturally form on the object. Of course, glass, metal and other products will have some special phenomena, but it is still inseparable from the three major color areas of light, gray and dark.

Five colors of sketch: light, gray, light-dark boundary, reflection and projection in the dark. In fact, in still life sketch, the description of objects is generally based on these colors. In general, the expression of these five tones may not be fully seen in products with special materials, such as glass and metal products.