1, the projection line of the point is perpendicular to the projection axis.
2. The distance from the projection of a point to the projection axis is equal to the distance from the point to the adjacent projection plane.
Three-sided projection law of points (in V/H/W three-sided projection system)
1, the projection line of the point is perpendicular to the projection axis.
2. The distance from the projection of a point to the projection axis is equal to the coordinates of the point, that is, the distance between the point and the corresponding adjacent projection plane.
In the related branches of geometry, topology and mathematics, points in space are used to describe 1 kind of special objects in a given space, and there are similarities in volume, area, length, width and height in space. 1 point is 1 0-dimensional object. As the simplest graphic concept, point is usually the most basic component in geometry, physics, vector graphics and other fields.
Extended data:
The projection on the V plane is called orthographic projection, which is represented by B'; The projection on the H plane is called horizontal projection, which is represented by B; The projection on the W plane is called side projection, which is represented by B ". Then rotate the projection plane, the V plane is fixed, and the H and W planes are rotated by 90 degrees in the direction of the arrow, that is, the three projection planes are expanded into one plane, so as to obtain the orthographic drawings of the three projections at this point.
The shadow (sun shadow for short) formed by an object under sunlight is a parallel projection. The direction of the sun shadow can reflect the time. The blue flag shadow clock in ancient Egypt and the ancient timer sundial in China all observe time according to the shadow of the sun. Shadow play is a kind of performing art that reflects the shadow shape on the screen (projection surface) by using natural light or candle light source.
Baidu encyclopedia-point projection