The projection strongly is associated with the exact sciences - geometry and drawing. However it does not prevent it to meet pretty often in far, apparently, not scientific and ordinary things: the subject shadow which lays down on a flat surface at solar lighting railroad cross ties, any card and any drawing already is not what other? as projection. Of course, creation of maps and drawings demands deep studying a subject, and here the simplest projections can be constructed independently, having armed only with a ruler and a pencil.
It is required to you
- * pencil;
- * ruler;
- * sheet of paper.
Instruction
1. The first way of creation of a projection is called the central design and especially is suitable for the image on the plane of objects when it is necessary to reduce or increase their actual size (Fig. a). The algorithm of the central design consists in the following: we designate the design plane (P') and the center of design (S). To design AVS triangle in plane P', we will see off through a point of center S and a point And, In and About direct AS, SB and SC. Their crossing with plane P' forms points And', In' and With' at which connection by straight lines we receive the central projection of a triangle of AVS.
2. The second way differs from described above only that straight lines by means of which tops of a triangle of AVS are projected in plane P', are not crossed, and are parallel to the designated direction of design (S). Nuance: the direction of design cannot be parallel to plane P'. At connection of points of design of A'B'C' we receive a parallel projection. Despite simplicity, skill of creation of such here simple projections perfectly helps to develop spatial thinking and can safely be considered as the first step in descriptive geometry.