The representation of technical objects is performed by one or more images that are determined by projecting the objects on an imaginary plane.

The display system is therefore defined by the position of said plane and the center of projection.

The position of the object relative to the center plane and can vary its representation, determining convergence in the projection, varying mediated, lines which are parallel in space.

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technical drawingis a graphical representation of system of various types of objects, in order to provide sufficient information to facilitate analysis, help develop your design and enable the future construction and maintenance.(W)

## Indeterminacy of the projection

The projection of a geometric element may overlap with other elements located in a different position in space.

Consider first the case corresponding to the projection of the point element.

By projecting a point **(P)** from a center of projection **(V..)** own the improper, the projection of the point P coincide with the points that are in the projecting beam **(P)**

A projection on a plane not only can restore the spatial information of the coordinates of the projected points. It has gone from a three-coordinate system to one of two in which it has lost much of the position information of the elements.

When projecting a straight **(r)** from a center of projection **(V..)** own the improper, r the projection of said line coincides with the straight lines are in the projecting plane** (P). **

In both chaos, projection of the line or point, reduce the representation of spatial information element thereof.

Each representation system solves this indeterminacy, inability to restore the three-dimensional information, differently, making it more or less suitable to a specific technical use.

## Solutions to indeterminacy

The solution is to expand the number of projections to determine the geometric, or add alphanumeric data that complement.

- A projection on a plane with numerical information
- Two different projections

- on the same plane
- on different planes, one of which is folded, projected or overlaps with the other

## Classification

Representation systems may be classified according to different criteria. Usually a classification has admitted collecting the most used and which is the next:

- System dihedral
- Axonometric Perspective
- Isometric
- Plans acotados
- Conical Perspective, linear system central

This classification may be raised based on the possible applications of the same. A "perspective" intuitively associate with a three dimensional representation similar to a photograph, in which volumes are interpreted naturally. The dihedral system with different views is a technical model primarily for industrial use.

## Projection types

Considering the classification criteria of conservation of the simple reason, concepts as projective, can make a classification that allows for similar operating models.

Conical | Cylindrical | |

Orthogonal | Oblique | |

In all projections cross ratio is preserved. Type cylindrical projections also retain the simple reason, can have a direction orthogonal or oblique to the plane of projection. The oblique direction affects especially the way you can measure in perspective.

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