If you are new to compositing, how objects and light interact may not be something you have stopped to think about. Yesterday, my goal was to demonstrate the first two basic principles of how objects and light interact…
- Light always runs in a straight line (therefore the absence of light also runs in a straight line) AND
- The higher the light, the shorter the shadow, the lower the light, the longer the shadow.
As simple and obvious as these two principles may seem, figuring out how light and objects interact is the single biggest hurtle I see new artists struggling with.
You are actually a master at perceiving light and shadow. Why? Because you have seen it all your life. The reason you can look at this image below and know immediately these models look like they are floating over the sidewalk is because you have seen the interaction of objects and light on a daily basis. You know what floating looks like.
The trick to fixing that illusion of floating is why we need to break down how objects and light interact into its basic principles. Once you do, you will know where to place and how dark to make your shadows so as to ground your subjects into the scene.
There are two more characteristics of light and shadow I want you to notice. First, shadows always run the same direction as the object it is hitting. It’s all lines. Straight lines. If the shadow is hitting a horizontal plane, then the shadow will run horizontal. If the shadow is hitting a vertical plane, then the shadow will run vertical. The shadow cast by this doll runs along the floor, but what happens when it hits a wall? It turns into a vertical shadow.
Now… there is one final characteristic I want you to notice about how objects and light interact and it has to do with how far your light source is from the subject. Did you notice the edge of the shadow, in the example above, was pretty defined and dark? That is dictated by how far the object is from the light source. The further away from the light source, the softer the edge is on the shadow. The closer the object is to the light source, the crisper the edge is on the shadow.
Four Key Principles
That’s it! These four basic principles of how objects and light interact will dictate how and where you need to draw in your shadows.
1. Light always runs in a straight line, therefore the absence of light (or shadows) also runs in a straight line.
2. The height of the light source affects how long the shadows are, that are cast. The higher the light, the shorter the shadows. The lower the light, the longer the shadows.
3. The distance of an object from the light source affects how crisp the edges are on your shadow. The closer the light, the more defined the edge. The further away from the light, the softer the edge.
4. Shadows run in the same direction as the plane it is hitting. The ground is horizontal, therefore the shadows cast upon it will run horizontal. A wall is vertical, therefore the shadows cast upon it will run vertical.
When you hit a brick wall…
I am not ashamed to admit that sometimes I just get turned upside down on this. When I do I get out my doll, a flashlight and make myself a small, mocked up scene. Pictures are worth a thousand words. Making a mock up is not 100% accurate but it gets you a LONG way when trying to figure out where to draw your shadows and how everything is working together. Just cutting out basic shapes and setting them up with similar lighting is sometimes all you need to get over the hump.
Now that you know how to decipher the locations and directions of shadows, on Monday I will be breaking down the three different brush settings you will need to use in order to draw them. Tomorrow is Free Stock Saturday! A perfect opportunity to apply the principles we just demonstrated.
Keep learning and keep #SharingItForward,
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