Collection of 2D drawings which
enables you to have a complete representation of an object is called
orthographic projection. Collection of 2D drawings consist of six orthographic
views (Top, Bottom, Right, Left, Front and Back view) also called as six
principle views. From these six orthographic views front, right side and top
view are most commonly used to represent the orthographic projection of an
object.

For getting the orthographic views from a 3D object there are two main
types of projections used one is First angle projection and other is Third
angle projection. Main objective of both of these projections angle is to
provide detail 2D drawings of 3D object but there are some differences in the
way one can get the projects by using one on these methods. Following are some
of the differences between First angle and third angle projection.

**Method of Projection**

To start getting projection first
divides the plane into four quadrants. For the first angle projection object is
paced in the first quadrant and for the third angle projection object is placed
is third quadrant.

**Object Placement**

To get first angle projection
object is place in between the plane of projection and observer and for the
third angle projection plane of projection is placed between the object and
observer.

**State of Projection Plane**

In first angle of projection plane
of projection is taken solid while in third angle of projection it is taken as
transparent.

**Views Sequence**

In first angle projection right
view come in left of front view and top view come at the bottom of front view
while in third angle projection right view come on right side of front view and
top view comes at the top of front view.

**Symbols**

First Angle difination

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ReplyDeletethis is one of the best ways to remember, first angle projection - planes are assumed opaque, third angle projection - planes are assume transparent

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