Hue which is a kind of subtle visual effect, is generally born of the factors, such as the relationship between cold and warm colors, the contrast between light and shade as well as the impression of space.

Five corresponding points of teaching of charcoal drawing were found through analysis of the uniqueness,which were the training of details,the training of abstract composition,the training of light and shade,the training of materials,and the training of view point and view angle.

Man has built the city as his living environment,and his mental health,spirit and behavior are in turn influenced by the environment directly or indirectly,positively or negatively through visual suggestions.