The ratio of corners and the planes of any subject visually changes depending on the provision of an object in space. For this reason the detail on the drawing is usually carried out in three orthogonal projections to which the spatial image is added. Usually it is an isometric projection. At its performance, descent points, as are not used at creation of frontal prospect. Therefore the sizes in process of removal from the observer do not change.
It is required to you
- - ruler;
- - compasses;
- - sheet of paper.
Instruction
1. The isometric projection is under construction in the system of three axes - X, Y and Z. Mark a point of their crossing as O. Os of OZ always goes strictly vertically. The others settle down to it under some corner.
2. Define the directions of axes. For this purpose draw from a point About a circle of any radius. Its central corner is equal 360º. Divide a circle into the 3rd equal a part, having used OZ axis as basic radius. At the same time the corner of each sector will be equal 120º. Two new radiuses just also represent axes of OX and OY necessary to you.
3. Imagine how the circle will look if to place it to the viewer under some corner. It will turn into an ellipse which has big and small diameters.
4. Define the provision of diameters. Halve corners between axes. Connect a point About to these new points thin lines. Position of the center of a circle depends on task conditions. Note it a point and carry out to it to both parties a perpendicular. This line will define the provision of large diameter.
5. Calculate the sizes of diameters. They depend on that, you apply coefficient of distortion or not. In an isometry this coefficient on all axes makes 0.82, but quite often it is rounded and taken for 1. Taking into account distortion big and small diameters of an ellipse are respectively 1 and 0.58 from initial. Without application of coefficient these sizes are 1, 22 and 0, 71 diameters of an initial circle.
6. Halve each diameter and postpone big and small radiuses from the center of a circle. Draw an ellipse.