Multiview Orthographic Projection

MULTIVIEW ORTHOGRAPHIC PROJECTION

The main objective of drawing orthographic projections of an object is to represent the true shape and size of the object. The object may be a building, machine part etc., but having three dimensions. Since it is not possible to represent the true shape and size of a three dimensional object on a two-dimensional drawing sheet, two (or) more number of views of the object are generally drawn, known as `Multiviews'. Hence, A multiview projection is an orthographic projection in which the exact shape of an object is represented by two (or) more separate views projected on planes which are mutually perpendicular to each other.

It is usual practice to draw the following views of an object in orthographic projection.

1. Front view or Elevation: To represent length and height of the object.

2. Top view or plan: To represent breadth and length of the object.

3. Side view, either left hand side view (L.S View) or Right hand side view (R.S View): To represent breadth and height of the object.

Why side view is necessary?

Though all the three dimensions, length, breadth and height can be represented on two views, Front view and Top view, for some of the complicated objects one more view is required to visualise the object.

For example consider the object shown in Fig. 9.3 (i).

For the position of the observer shown in Fig. 9.3 (i), the front view and top view of the object are shown in Fig. 9.3 (ii) and (iii) respectively. It is interesting to see both front view and top view are same with respect to the shape, from which the actual shape of the object shown in Fig. 9.3 (i) cannot be visualised. Hence one more view is necessary to understand the actual shape and size of the object. This third view is normally the side view, either left hand side view (L.S View) or Right hand side view (R.S View) of the object. For the object shown in Fig. 9.3(i), Left hand side view is shown in Fig. 9.3 (iv).

The plane used for obtaining front view is known as vertical plane (VP), the plane used for top view is known as Horizontal plane (HP) and the plane used for side view (Either left hand side view (or) Right hand side view) is known as `Profile plane' (PP).