Convergent Systems of Drawing or Perspective Drawing is a method of producing distorted illustrations that mimic the way in which we see and experience objects and environments in real life. It can efficiently communicate the form and experience of an object or environment without the need to decode abstract representations as like those in plan and elevation drawings. This is of significant advantage when communicating with a client about how the interior of their house may look or how your target audience will be able to ergonomically interact with a functioning piece of machinery.
Find a friend and stand facing each other just further away than arm's reach. One of you step half a step to one side so your shoulder is in line with the middle of the other's chin. With the arm that is further from your friends, reach out towards your friend as though you trying to grasp something just outside of your reach at eye level of your friend. Holding the pose, compare the size of your friend's hand to the size of their head. What do you notice?
Methods of Projection
There are two techniques used for constructing a perspective view of an object or environment, plan projection and direct perspective. However, of these two techniques only one is ever useful for conceptualising and exploring ideas that have not yet been designed.
Plan projection requires the complicated and time consuming process of using plan or elevation views to project a perspective view. For a designer, this form of perspective is not only time consuming but is fundamentally flawed because it requires a pre-finished plan or elevation of the product or environment. This means that if a perspective drawing is to be drawn, it is after all of the design decisions have been made and its only purpose is to 'sell' the final design.
Direct Perspective allows a designer to perceive an object or environment. It is based on the technique of using two vertical planes to indicate the width and depth of the space. Although this means that the drawing will not be as mathematically correct as Plan Perspective it can be based on the ideal of the scale and dimension of the human figure. This also means that perspective is an equal participant in the design process and allows for study of the experienced quality of the design.