Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Define and differentiate between one-point, two-point, and three-point perspective.
• Construct a one-point perspective drawing of a simple object.
• Construct a two-point perspective drawing of a simple object.
• Apply techniques for accurate measurement and proportion.
• Identify and correct common errors in perspective drawings.

Lesson summary

Perspective drawing is a crucial skill in Engineering Graphics and Design. It allows us to represent three-dimensional objects realistically on a two-dimensional surface, mimicking how the human eye perceives depth and spatial relationships. This is particularly important in fields like architecture, interior design, product design, and even urban planning. In South Africa, where we are constantly shaping our built environment and infrastructure, understanding perspective drawing enables us to visualize and communicate designs effectively.

Lesson notes

What is Perspective Drawing? Perspective drawing is a technique used to create the illusion of depth and three-dimensionality on a flat surface. It relies on the principle that objects appear smaller as they recede into the distance and that parallel lines converge at a point on the horizon line. This creates a more realistic representation of how we see the world compared to parallel projection techniques like orthographic projection.

Key Terminology: Horizon Line (HL): Represents the eye level of the viewer. All vanishing points lie on the horizon line.

Vanishing Point (VP): The point on the horizon line where parallel lines appear to converge. The number of vanishing points determines the type of perspective.

Station Point (SP): The position of the viewer's eye. It influences the perspective effect.

Picture Plane (PP): The imaginary flat surface on which the drawing is created. It is the plane that intersects the objects being viewed.

Ground Line (GL): The line where the ground plane intersects the picture plane.

Measuring Line (ML): A vertical line in a perspective drawing that helps to accurately represent the height of objects.

Types of Perspective: One-Point Perspective: Used when looking directly at one face of an object. One set of parallel lines recedes to a single vanishing point on the horizon line. All other lines are either vertical or horizontal.

Example: A long hallway, a road stretching into the distance, or the front façade of a building viewed straight on.

Two-Point Perspective: Used when looking at an object from an angle. Two sets of parallel lines recede to two vanishing points on the horizon line. Vertical lines remain vertical.

Example: Viewing the corner of a building, a table seen from the side, or an interior scene. This is the most common type of perspective used in architectural drawings.

Three-Point Perspective: Used for dramatic viewpoints where the viewer is either looking up at a tall object or down from a high vantage point. Three sets of parallel lines recede to three vanishing points – two on the horizon line and one above or below it. Vertical lines converge as well.

Example: Skyscrapers viewed from the ground, a wide-angle view of a city from a rooftop. Less commonly used than one- and two-point perspective.

Construction Techniques: One-Point Perspective: Draw the horizon line (HL) and mark the vanishing point (VP) on it. Draw the front face of the object as a rectangle. Draw lines from each corner of the rectangle to the vanishing point. These are called vanishing lines. Decide how far back the object extends and draw another rectangle using the vanishing lines as guides. Erase the portions of the vanishing lines that are behind the object.

Two-Point Perspective: Draw the horizon line (HL) and mark two vanishing points (VP1 and VP2) on it. Draw a vertical line representing the corner of the object closest to the viewer. This is the leading edge. Draw lines from the top and bottom of the leading edge to both vanishing points. Decide how wide and deep the object is and draw vertical lines to define the other corners. Draw lines from these new corners to the opposite vanishing points. Erase the portions of the vanishing lines that are behind the object.

Example 1: One-Point Perspective - Drawing a Simple Room Imagine you are designing a bedroom for a new RDP house. Let's draw it in one-point perspective.

Horizon Line and Vanishing Point: Draw a horizontal line (HL) to represent the horizon. Place a dot on it to represent the vanishing point (VP).

Back Wall: Draw a rectangle below the HL. This represents the back wall of the room. Let's say the rectangle is 4cm wide and 3cm high.

Vanishing Lines: Draw lines from each corner of the rectangle to the vanishing point.

Front Wall: Decide how deep the room is. Let's say 5cm. Draw a horizontal line on each of the vanishing lines (starting from the top and bottom lines respectively) that will form the width of the front wall. Complete the rectangle.

Details: You can now add details like a door, window, or furniture using the same principles of vanishing to the V

P. For instance, a window would have its top and bottom lines vanishing toward the V

P. Example 2: Two-Point Perspective - Drawing a Building Corner Imagine you are an architect designing a new school building.

Horizon Line and Vanishing Points: Draw a horizontal line (HL) and mark two vanishing points, VP1 and VP2, on it. VP1 and VP2 should be spaced apart.

Leading Edge: Draw a vertical line below the HL. This will be the corner of the building closest to you. Let's say this line is 6cm long.

Vanishing Lines: Draw lines from both ends of the vertical line to both VP1 and VP

2. Width and Depth: Decide how wide and deep the building will be. Draw vertical lines to represent the other two corners that form the sides of the building.

Completing the Shape: Draw lines from these new vertical lines to the opposite vanishing points.