Important Notation In Engineering Graphics
· HP means the Horizontal Plane
· VP means the Vertical Plane
· FV means the Front View
· TV means the Top View
· SV means the Side View
· STV means the Sectional Top View
· GR means the Ground
· TL means the True Length
· CP means the Cutting Plane
· PPP means the Picture Plane for Perspective Projection.
Key Points About The Projections Of Points:
1. The front view and the top view of a point are always on the same vertical line.
2. The distance of the front view of a point from the XY line is always equal to the distance of the given point from the HP.
3. If a given point is above the Hp, its front view is above the XY line. If the given point is below the Hp, its front view is below the XY line.
4. The distance of the top view of a point from the XY line is always equal to the distance of the given point from the VP.
5. If a given point is in front of the VP, its top view is below the XY line. If the given point is behind the VP, its top view is above the XY line.]
Key Points About The Positions Of A Point And Its Projections:
Projections Of A Line Inclined To Both The Reference Planes:
Case I:
If a straight line is projected when it is inclined at e to the HP and either parallel to the VP or inclined to the VP, then:
(i) The length in the top or plan view remains the same and
(ii) If one end point in the FV remains at constant distance from XY, the other end point will also remain at the same distance from XY, provided the angle with the HP does not change. In other words, if point A of a straight line AB is fixed, point B will have its front view b’ on a path parallel to the XY line.
Case II:
If a straight line is projected when it is inclined at q; to the VP and either parallel to the HP or inclined to the HP, then:
(i) The length in the front view remains the same and
(ii) If one end point in the TV remains at a constant distance and if the angle from XY with the VP does not change, the other end point will also remain at the same distance from XY. In other words, if point A of a straight line AB is fixed, point B will have its top view b on a path parallel to the XY line.
