One of the most fascinating problems of descriptive geometry – creation of the third look at set two. She demands thoughtful approach and pedantic measurement of distances therefore she is not always given from the first. Nevertheless if carefully to follow the recommended sequence of actions, to construct the third look quite perhaps, even without spatial imagination.
It is required to you
- - sheet of paper;
- - pencil;
- - ruler or compasses.
Instruction
1. First of all try to determine a form of separate parts of the represented subject by two available types. If on the top view the triangle is represented, then it can be a triangular prism, a rotation cone, a triangular or quadrangular pyramid. The cylinder, a quadrangular or triangular prism or other objects can take the form of a quadrangle. The image in the form of a circle can mean a sphere, a cone, a cylinder or other surfaces of rotation. Anyway, try to present the general form of a subject in general.
2. Line borders of the planes, for convenience of transfer of lines. Begin transfer from the most convenient and clear element. Take any point which you precisely "see" on both types and transfer it to the third look. For this purpose lower a perpendicular on borders of the planes and continue it on the following plane. At the same time consider that upon transition from the left-side view to the top view (or on the contrary), it is necessary to use compasses or to measure distance by means of a ruler. Thus, on the place of your third look two straight lines will be crossed. It will also be a projection of the chosen point to the third look. In the same way it is possible to transfer some points until to you there is clear a general view of a detail.
3. Check correctness of construction. For this purpose measure the sizes of those parts of a detail which are reflected completely (for example, the standing cylinder will be one "growth" on the left-side view and the front view). To understand whether you forgot anything, try to look at the front view from the observer's position from above and to count (at least approximately) how many it has to be visible borders of openings and surfaces. Each straight line, each point have to have reflection on all types. If the detail is symmetric, do not forget to note an axis of symmetry and to check equality of both parts.
4. Remove all auxiliary lines, check that all invisible lines were noted by a dashed line.