Understanding Form: Drawing A Sphere From Imagination

In this lesson, artist and instructor Mackenzie Swenson shows you how to render a highly realistic sphere entirely based on logic and imagination! This kind of “conceptual drawing” is also known as “form drawing”, as it is a sculptural that uses an understanding of the subject’s surface and volume (“form”) to inform the rendering process.

First, Mackenzie explains how to set up your conceptual sphere on the page using a household item like an aerosol cap or the lid of a jar to draw a circle. She then shows you how to choose your light source and a groundline, followed by finding the shadow shape by using creating straight lines from the outside of the light source to the contour of the sphere and then the floor plane. Mackenzie shows you how to identify the curvature of the sphere’s shadow by choosing the depth of your light source, and how to connect the points on the floor plane to create a believable cast shadow. At this point, you will have a well-constructed linear block-in that is prepared for shading and rendering.

Mackenzie then explains a few important terms, starting with the contour, light-shape, and shadow-shape, as well as how to identify each of those elements in your drawing. She shows you how all shadows subdivide into “form” and “cast” shadows, and a few useful tricks for finding exactly where that line between light and shadow falls. The boundary on the form between light and shadow is known as the “terminator” because this is the point at which the light from the main light source terminates. To complete the discussion on terminology, Mackenzie describes how all areas in the light shape can be understood through their relationship to the light source by asking the question “how light-facing is this moment on the form?”

Once the terms are set, Mackenzie demonstrates the process of flattening your shadow (for more on this see “Instantly Improve Value Consistency in Pencil”) followed by rendering the light shape of the sphere by using strips of value gradations to move from the terminator to the most light-facing point on the sphere. Mackenzie follows this process through to completion, demonstrating how a conceptual understanding of light and form can create a highly convincing 3D illusion!

For this exercise, Mackenzie uses Strathmore Series 400 paper, Staedtler graphite pencils in grades HB and 2H, a Tombow Mono eraser, a kneaded eraser, a ruler, and a circular household item that is between 1 and 2 inches in diameter. Keep in mind that your pencils need to be extremely sharp to get the best results from this exercise. For additional instruction on how to effectively sharpen your pencils, see “Sharpening Pencils and Charcoal” with Savannah Tate-Cuff.