EG
UNIT 2
Orthographic Projections
1. What are the four methods of projection?
Following four methods of projection are commonly used,
1) Orthographic projection.
2) Isometric projection.
3) Oblique projection.
4) Perspective projection.
2. What are the nine type of projections of point?
There are basically nine type of projections of point is space :
- In FIRST Quadrant (Above H.P. , In front of V.P.)
- In SECOND Quadrant (Above H.P. , Behind V.P.)
- In THIRD Quadrant (Below H.P. , Behind V.P.)
- In FOURTH Quadrant (Below H.P. , In front of V.P.)
- In PLANE (On V.P. , Above H.P.)
- In PLANE (On H.P. , Behind V.P.)
- In PLANE (On V.P. , Below H.P.)
- In PLANE (On H.P. In front of V.P.)
- In PLANE (On both H.P. & V.P.)
3. Write the notations for : Projection Of Lines .
- True length of the line: Denoted by Capital letters. e.g. AB=100 mm, means that true length of the line is 100 mm.
- Front View Length: Denoted by small letters. e.g. a’b’=70 mm, means that Front View Length is 70 mm.
- Top View Length: Denoted by small letters. e.g. Ab=80 mm, means that Top View Length is 80 mm.
- Inclination of True Length of Line with H.P.: It is denoted by θ. e.g. Inclination of the line with H.P. (or Ground) is given as 30º means that θ = 30º.
- Inclination of True Length of Line with V.P.: It is denoted by Φ. e.g. Inclination of the line with V.P. Is given as 40º means that Φ = 40º.
- Inclination of Front View Length with XY : It is denoted by α. e.g. Inclination of the Front View of the line with XY is given as 50º means that α = 50º.
- Inclination of Top View Length with XY : It is denoted by β. e.g. Inclination of the Top View of the line with XY is given as 30º means that β = 30º.
- End Projector Distance: It is the distance between two projectors passing through end points of F.V. & T.V. Measured parallel to XY line.
4. Draw Line Parallel to two Planes and Perpendicular to the third plane.
5. Draw Line Inclined to one Plane and Parallel to another.
6. Draw Line Inclined to both the Planes.
7.
8.
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