Descriptive geometry - what is the frontal plane?

To get an idea of the subject, use his image on paper or a screen. Usually the image of an object from one of the sides does not give a full idea of its form, it is required to get its projections into two or three planes. To order the projection process, the planes to which the projection is projected are perpendicular to each other. Let us consider what kind of planes exist. There are three in all, and they form a triangular right angle in space.

Each of the planes of projection has its own name and letter designation. The frontal plane is a plane of projections vertically before our eyes. For clarity, this is the plane to which we are facing, that is, the plane of the picture we are considering. The frontal plane is denoted by the Latin letter V.

The horizontal plane is perpendicular to the frontal plane. Figuratively speaking, the horizontal plane is the plane that lies beneath our feet. It is usually denoted by the letter H.

The third of the main planes of projections is called the profile plane. Like the frontal plane, it is located vertically and forms a right angle with the two previous ones. Denote the profile plane by the Latin letter W.

In the pairwise intersection of these three planes, the axes of the projections x, y, z are formed. These are mutually perpendicular rays with a common vertex at the intersection point of all three planes of projections, denoted by the letter O.

To get an expanded image of an object, you want to combine its images obtained on three mutually perpendicular faces. To do this, the two faces of the angle are unfolded and combined with the third. The frontal plane remains in place, the horizontal plane rotates 90 ° down along the x axis, the profile plane rotates 90 ° to the right along the z axis. Thus, the last two planes are combined with the frontal plane (the horizontal plane is located below it, the profile one is on the right).

In any descriptive geometry, any arbitrarily placed plane in the drawing can be specified in different ways: the projections of three points not lying on one straight line, the projection of the line and the point located outside it, and also the projections of parallel or intersecting lines or a plane figure.

Concerning the basic planes of projections, the plane under consideration can occupy the following positions:

1. It can be non-perpendicular to none of them. Then it is so-called. Plane of general position.

2. It can be perpendicular to one of the three projection planes. In this case, it is called horizontally-projecting, profile-projecting or front-projecting, respectively, the plane to which it is perpendicular.

3. The plane may be perpendicular to two of them and parallel to the third one. Then it is called frontal, horizontal or profile, respectively.

A straight line can occupy the following positions with respect to a plane:

1. To belong to her.

2. To be parallel to it.

3. Cross the plane (special case - in the form of a perpendicular)

The plane has major lines, which are called horizontals and fronts. These are lines that lie in the plane and are parallel to the corresponding planes of projections.

Any plane can be represented in the form of so-called. Traces of the plane, that is, lines along which it intersects with the planes of projections. Traces of the plane are also called horizontal, frontal and profile. At points of intersection with the plane of the axes of projections on the axes, points of mutual intersection of traces of the given plane arise, which are usually referred to as points of traces of the plane.

The horizontal and frontal traces of the plane on the planes of projections coincide with their projections of the same name. It should also be mentioned that any horizontals of the same plane are mutually parallel and parallel to its horizontal track, and any of its fronts are also mutually parallel and parallel to its frontal track.