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 

  1. Look at the pictorial view fig (i). Point A lies in the first quadrant.
  2. 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.
  3. 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.
  4. 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)
  5. 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.
  6. Top View: On the small projector, mark the top view a 45mm below XY.

Projection of points

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