When performing technical drawings, together with the mark of the items and details in the orthogonal projections, are required to have a visual image.It uses the method of construction axonometric.
It consists of the following: the subject together with the coordinate system (mutually perpendicular axes X, Y, Z), with which it is associated in the space is projected on a plane parallel to the axonometric projection (or image plane).The projection of the object on the plane called axonometry.It also displays the coordinate axes called axonometric axes.It should be borne in mind that the projection direction should be chosen so that there is no match with either of the coordinate axes.
perspective view of a perpendicular projection called rectangular or orthogonal, and a non-perpendicular - oblique.
ordinary objects arranged so that on the surface of the picture you could see three sides of the object: the bottom, top, front, left or right.A perspective drawing is to give the most complete picture of the subject, its magnitude and constructive manner.Its main advantage - the visibility.
All axonometric projection can be classified as follows:
1. Isometric.In this case all three axes have the same inclination, and all the sizes in the direction of the three axes have the same reduction.
2. dimetric.Two coordinate axes in these projections have the same slope, and the third - the other.Accordingly, the first two axes of size reduction is the same, and on the third - otherwise.
3. Trimetric.All three axes in this case have different slopes and different size reduction in all three axes.
Having depicted object differently on different surfaces and choosing direction of the rays, you can get a variety of perspective view of the same subject.
most commonly used in the construction drawings isometric rectangular projection, which reduce the size of the coefficient is the same for all axes and angles between the coordinate axes are 120 degrees perspective.It is produced in a parallel fashion.
Almost everyone who has studied engineering graphics and drawing, had to carry out the construction of perspective view.In practice, a wide selection of these figures is very limited requirements of low labor intensity and clarity.GOST 2.317-69 is recommended axonometric projection that allow good viewing experience, with a good combination of factors have distorted and simple construction.These include five types: three oblique (front, horizontal isometric, front diameters) and two rectangular (diameters and isometrics).Of course, they can not replace the projection drawing, and can only be supplemented.Building perspective rather cumbersome, it is used when the drawing does not give a complete picture of the shape of parts or all of the depicted object.
