Different between 1st angle projection and 3rd angle projection in drawing

Orthographic projection  is a means of representing a three-dimensional object in two dimensions. It is a form of parallel projection, where all the projection lines are orthogonal to the projection plane, resulting in every plane of the scene appearing in affine transformation on the viewing surface. A lens providing an orthographic projection is known as an (object space) telecentric lens.

There are two types of drawing in orthographic , First Angle and Third Angle. They differ only in the position of the plan, front and side views. First angle orthographic projection  used mainly in Europe.  Third angle which is used in USA.

 

Orthographic 1st angle and 3rd angle Projection

Orthographic 1st angle and 3rd angle Projection

First Angle Projection
Third Angle Projection
 Object is imagined in 1st quadrant
 Object is imagined in 3rd quadrant
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Object is located between observer and plane of projection
Object is located between observer and object
the plane of projection assumed to be non transparent
the plane of projection assumed to be transparent
Learn more : orthographic  Drawing 
Learn more about with animation orthographic  Drawing 

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