Orthographic Projections
ORTHOGRAPHIC PROJECTIONS :
It is a technical drawing in which different views of an object are projected on different reference planes observing perpendicular to a respective reference plane
Different Reference planes are
Horizontal Plane(HP),
Vertical Frontal Plane(VP)
Side or Profile Plane(PP)
And
Different Views are Front View(FV), Top View(TV) and Side View(SV)
FV is a view projected on VP.
TV is a view projected on HP.
SV is a view projected on PP.
Important terms of orthographic projections:
- Planes.
- A pattern of planes & Pattern of views
- Methods of drawing Orthographic Projections
1 ] planes...
2 ] A pattern of planes & Pattern of views...
this is a pictorial set-up of all three planes. Arrow direction is a normal way of observing the object. But in this direction only VP and A View on it (FV) Can be seen.
The other Planes and views on those can not be seen.
procedure to solve the above problem.
- HP is rotated 90º downward.
- PP, 90º in the right side direction.
This way both planes are brought in the same plane containing VP.
HP is rotated downward 90º AND Brought in the plane of VP.
PP is rotated in the right side 90º AND Brought in the plane of VP.
Actual pattern of plane & views of orthographic projections drawn in first angel method of projections.
3 ] Method of drawing orthographic projections
- First angle projection method.
- Third angel projections method.
The symbolic presentation of both methods with an object standing on HP ( GROUND ) on it's base.
First angle projection method.
Here view are drawn by placing an object in 1st Quadrant ( FV above X-Y, TV below X-Y )
note : HP term is used in 1st angle method of projections.
Third angel projections method.
Here view are drawn by placing an object in 3rd Quadrant ( TV above X-Y, FV below X-Y )
note : GROUND term is used in 3rd angel method of projections
