Hello! Welcome back to your digital art course.
In our last lesson, we focused on value, learning how to create a full palette of grays from pure white to pure black. You practiced the digital techniques for selecting these values and blending them smoothly, which are essential skills for rendering.
Today, we move from the "what" (values) to the "where" and "why." Our learning outcome is to determine the direction of a light source and predict how it will illuminate a form. We'll explore the fundamental rules of how light behaves when it hits an object. Understanding this is the key to placing your values correctly and making your 2D drawings appear convincingly 3D. This is a crucial theoretical step before we can start rendering the complex forms of the human body.
1. The Light Side, the Shadow Side, and the Terminator
At its most basic, when light from a single source hits an object, it divides the object into two distinct zones: a side that is lit and a side that is in shadow. The boundary between these two zones is one of the most important concepts in rendering.
To introduce this idea, let's watch a short clip.
Basic rules of light and shadow for drawing _ Beginner's Tutorial
This video from the Peonypaint channel provides a simple and clear introduction to the basic principles of light, including the direction of light and the division between the light and shadow sides of a form.
Watch from 00:49 to 01:59. Pay close attention to the following concepts: The idea of parallel light rays, like those from the sun. The clear division of a sphere into a light side and a shadow side. The definition of the terminator: the edge or line where the form transitions from light into shadow.
As the video explained, the terminator is the critical dividing line. It's the point where the surface of the object curves away and is no longer directly lit.
Here is a diagram that labels all the key elements of light and shadow on a simple sphere. For today's lesson, focus on the Light Source, Terminator, and the overall division between light and shadow. We will cover the other terms in subsequent lessons.
2. How the Light Source Changes the Shadows
The simple model of parallel light rays from the sun is a great starting point, but the characteristics of the shadows change depending on the nature of the light source. The two most important factors are the light's distance and its size.
Let's explore this with another video.
What I learnt doing lighting studies for 30 days
The creator of the Bluebiscuits channel documented their experience with lighting studies. In this segment, they explain how the light source's distance and type affect the shadows it creates.
Watch the clip from 14:48 to 16:10. The video illustrates a key distinction: Distant light source (e.g., the sun): Light rays are effectively parallel, creating shadows that are also parallel and consistent in size. Near light source (e.g., a lamp): Light rays radiate outwards from the source, causing shadows to fan out and grow larger with distance.
This distinction is important for prediction. When you're drawing a landscape or an outdoor scene, you can assume all shadows will be cast in the same parallel direction. When drawing an indoor scene with a lamp, you must account for the shadows radiating away from that single point.
Additionally, a small, intense light source (like a bare bulb or direct sun) creates hard-edged shadows. A large, diffuse light source (like an overcast sky or a softbox lamp) creates soft-edged shadows. We will focus on hard lighting for now, as the boundaries are clearer and easier to study.
3. Predicting Illumination Based on Light Direction
The position of the light source relative to the object has a dramatic effect on how we perceive its form. By changing the light's direction, you can emphasize texture, create drama, or flatten an object's appearance.
The same video from Bluebiscuits provides an excellent overview of the most common lighting directions.
What I learnt doing lighting studies for 30 days
Let's continue with the Bluebiscuits video to see a breakdown of how different light directions affect a subject.
Watch from 10:32 to 11:57. The creator explains the effect of: Front lighting: Flattens form, reveals detail. Side lighting: Emphasizes texture and 3D form. Back lighting: Creates a silhouette with a 'rim light' effect.
To solidify these concepts, look at the image below. It shows these exact principles applied to a more complex form—a human bust. This gives you a direct preview of how these lighting rules apply to the figure.
Notice how side lighting (c) clearly defines the cheekbones and nose, making the form feel very three-dimensional. In contrast, front lighting (a) makes the face look much flatter because there are very few visible shadows. Understanding these effects allows you to choose your lighting to best describe the form you are drawing.
4. Practice: Predicting Shadows
Now it's time for a practical exercise. Your goal is not to create a finished rendering, but simply to predict and block in the shadow shape based on a chosen light direction. This isolates the skill of prediction.
Estimated time: 15-20 minutes
- Setup: In Procreate, open a new canvas. On one layer, draw four to five simple spheres. You can use the QuickShape tool to make perfect circles.
- Choose Light Directions: For each sphere, decide on a light direction. A helpful tip is to draw a small arrow on a separate layer next to each sphere to indicate where the light is coming from (e.g., top-right, front, side-left, back-left).
- Block in the Terminator: On a new layer, select a middle-gray value (around 50% brightness). For each sphere, visualize how the light would hit it from the direction you chose. Then, using your brush, fill in the entire shadow side of the sphere.
- If the light is from the side, the terminator will be a straight line down the middle.
- If the light is from the front, most of the visible sphere will be lit, with only a thin crescent of shadow on the edges.
- If the light is from the back, most of the visible sphere will be in shadow, with only a thin crescent of light (a "rim light") on the edge closest to the light source.
Don't worry about smooth blending, reflected light, or cast shadows for now. The only goal is to correctly place the terminator and establish the main shadow shape. This is the foundational decision upon which all other rendering is built.
Conclusion
Excellent work. Today you've moved from simply creating values to understanding the logic of light that dictates where those values should go. This is a huge leap towards creating believable and solid-looking forms.
Key Takeaways:
- A single light source divides a form into a light side and a shadow side.
- The boundary between light and shadow is called the terminator. Its location and shape tell us the direction of the light.
- A distant light source (like the sun) creates parallel shadows, while a near light source (like a lamp) creates radiating shadows.
- The direction of light (front, side, back) dramatically changes how we perceive a form's three-dimensionality.
You now know how to determine the light side and the shadow side of an object. In our next lesson, we will look more closely at the shadow side itself, learning to distinguish between the two types of shadows that exist in any scene: form shadow and cast shadow. This will add another layer of depth and realism to your work.