The size of the perspective view depends of the Position of picture plane relative to   the object . referring to figure 3, 

• When the object is placed behind the picture plane, the perspective  will show object reduced in size.
• When the object is placed in front of the picture plane, the perspective  will show object enlarged  in size.
• When the picture plane coincides with the object, The perspective  will show the true size of the object.

Figure 3. Illustrates the size of the perspective view with respect to the position of the picture plane  and the object.

1. Visual Ray Method

In the visual ray method,  the points on the perspective are obtained  by project ting  the top view with either the front view or the side view of the visual rays. The method of drawing the perspective by visual ray method is illustrated by the problem below;
Problem 1.
A hexagonal lamina of 45 mm edge lies on the ground.  The corner which is nearest to PPP is 25 mm behind it and an  edge containing that corner is making 50° to PP. The station point is 50 mm in front of  PPP. 60 mm above Ground plane and lines in a central plane which is  80 mm to the left of the corner nearest to PPP. Draw the perspective view of the lamina by visual ray method.
Solution: The solution to the problem is illustrated in figure 4.

Figure 4. Step wise method of drawing the perspective view for problem 1.