Projection of Points
Sample Problem 1:
Point A is 30mm above HP and 45mm infront of VP. Draw its Front View and Top view.
Steps for Projection of Points
- Look at the pictorial view fig (i). Point A lies in the first quadrant.
- To obtain the Front View a’, look at the Pictorial View from the front.
Point A is 30mm above HP. Aa’ is the projector perpendicular to the VP. Hence a’ is the Front View of the Point A and it is 30mm above the XY line.
- To Obtain the Top View a, look at the pictorial View from top.
Point A is 45mm infront of VP. Aa is the projector perpendicular to the HP.
Hence a is the Top view of the point A and it is 45mm infront of XY.
- To convert Projections a’ and a from pictorial view into Othographic Projections.
> Rotate HP about XY line through 90º in the CW direction as shown in fig (i).
>After Rotation, first quadrant is opened out and the HP occupies the position (dashed line) vertically below the VP.
>Also, the point a, on HP will trace a quadrant of a circle with O as center and oa as radius. Now , a occupies the position just below O.
> See fig (ii) Line Joining a’ and a, called Projector, is perpendicular to XY.How to draw the orthographic projections on the drawing Sheet: fig(iii)
- Front View: See fig(iii). Draw the XY line and draw the Projector at any point on it.Mark the Front View a’ 30mm above XY on the projector.
- Top View: On the small projector, mark the top view a 45mm below XY.
Video Lectures of Projections of Points