definition
The method of making the projection line pass through a point or other object and project on the selected projection surface to get the graphics on this surface is called projection method.
Projection method can be divided into center projection method and parallel projection method.
Projections commonly used in engineering include polyhedron orthographic projection, axonometric projection, elevation projection and perspective projection. Among them, polyhedral orthographic projection is the most commonly used and important projection in engineering. [2]
App application
geometry
From the perspective of junior high school mathematics, generally speaking, when an object is irradiated with light, the shadow is obtained on a certain plane (ground, wall, etc.). ) is called the projection of an object, the irradiated light is called the projection line, and the plane where the projection is located is called the projection plane.
Sometimes time is a set of parallel lights, such as sunlight or searchlights. The projection formed by parallel rays is a parallel projection. The projection formed by the same point (light from a point light source) is called central projection. The projection produced by the projection line perpendicular to the projection plane is called orthographic projection. The projection that the projection line is not perpendicular to the projection plane is called oblique projection. The shape and size of the object projection are related to its position and angle relative to the projection plane.