25. Geometric bodies and their display

An eometrical body is considered as the set of all points belonging to it, interconnected and bounded in space accordingly. It can move in space without changing the relative position of its elements.

In engineering graphics, one-dimensional bodies (line segment), two-dimensional (flat figure, surface compartment), three-dimensional (any three-dimensional figure) are considered. The main objects of the image on flat drawings are three-dimensional geometric bodies surrounding us in real three-dimensional space.

Complex geometric bodies can also be viewed as consisting of simpler three-dimensional shapes, which are determined by the main formative elements of space - points, lines, surfaces.

Geometric bodies in the drawings are obtained by the display method. The display of a geometric body is a concept according to which each point of three-dimensional space corresponds to a specific point of two-dimensional space in the drawing. Mapping of geometric bodies can be performed on a plane or some other surface. The course of engineering graphics deals with the display of geometric bodies on a plane. The image of a geometric body on a plane can be obtained by projecting its points on this plane.

The geometric connection between a geometric body located in space and its display in a drawing on a plane are established according to the laws of projection, which are based on the principle of one-to-one correspondence.