These diagrams show a simple technique to help you determine the proportions of your object as it recedes into space. You can apply this technique to either a vertical or horizontal plane, as shown.

The first diagram uses the horizontal plane. To draw this diagram, first draw a triangle, and then draw some converging lines within the triangle. These lines correspond to the sides of an object that you may be drawing (such as a tabletop or the top of the kitchen island shown previously), which are receding to the vanishing point. Draw a horizontal line across two lines in the bottom on the left. Now you have a top surface of an object. The red line represents the width of that top surface of the object, from corner to corner. If you repeat this diagonal with the same angle, so that it is parallel to the first and all subsequent diagonals all the way to the vanishing point, you can see how the top surface of the object becomes smaller and smaller in width and length.

Vanishing Point and Eye Level

Vanishing Point and Eye Level

Viewer or Vantage Point

In this diagram, imagine that the square nearest to you is the back of a chair in perspective. Notice that if you move that chair farther away from the viewer and closer to the vanishing point, along the trajectory that is mapped out, it becomes smaller. Its proportions are correctly portrayed as the red diagonal lines. Just as in the previous example, all of the diagonal lines are parallel to each other. In this example, the diagonal lines form the correct width of the chair back. You can drop a vertical line where the diagonal meets the top side of the chair. (The top side is parallel to the bottom side of the chair.)

An example where this technique is useful is when you are drawing windows on a wall of a building that is receding into the distance.

Viewer or Vantage Point

 79

Once you understand the terms vanishing point and horizon line, you can move an object around within a space, even if it doesn't happen in real life.

Here is a diagram of two cubes in a three-dimensional space. These cubes, which obey the laws of one-point perspective, are the same size. As you can see, if you place an object on a surface (floor or table) and draw lines to its vanishing point, you are able to place it anywhere between the foreground and background and still maintain its correct proportions.

This is a very useful technique for constructing a room with furniture that does not exist in reality. If you apply the laws of one-point perspective, you can convincingly achieve the illusion of reality. Practice this exercise by drawing a cube, placing it in a grid, and moving it around your space.

Horizon Line Vanishing Point

Horizon Line Vanishing Point