In this short lesson we will look at how light effects the way objects look when interacting with it. It sounds obvious to say, without light we can not see anything, but equally true is that the kinds of light influences how much we can or can’t see.
In the illustration below you will see that we have the light source entering from the left. This causes the light to create a highlight or point of bright intensity on our object. As the surface of the object turns away from the light, less light reaches this side and creates a shadow or areas of less intensity. Thus the less light that reach these areas the darker it get.
You will see on the very edge of the object, on the shaded side, it starts to get slightly lighter again. This effect is called reflected or bounce light. This is caused by light bouncing or reflecting off the surface on which our object rests. If the surface were darker, it would cause less or no reflected light, depending on how dark it is.
Because our object is solid, it will prevent the light from reaching the surface on which it rests. This causes the object to cast a shadow on the surface.
I spoke about the kinds of light in the first paragraph. To simplify and explain the way light travel through air, let’s think of it like a little ball for each ray of light. Our atmosphere is saturated with dust and water particles. As light travels through the air, these particles disturb the rays as they fire away from the source. Thus they start to bounce around and create what we call ambient light. If we were to go to the moon, you will never be able to see in the shadows, because there is no atmosphere to create ambient light. On the moon you only get light and dark. There is no real gradient or soft transition from light to dark.
Please look at the illustration below. You will see that while the dark side is in the shade, you can still see the wall. It is not just an even black. Look closely at the areas that I have marked as Ambient Occlusion. To explain this, let’s think again of the rays as little balls. It is easy for a ball to bounce against surfaces, but it is less likely that it will bounce all the way into corners. It would rather bounce away from tight areas. Light works in a similar way, it finds it harder to reach into deep corners and thus is occluded or kept from these areas.
It is always fascinating to really “see” the world around us. I hope you start to observe everything I have explained. Always try to see where the light is coming from, where it will create highlights on objects, how it influences the shadows and reflected light on objects and where it creates ambient occlusion. Hope you have loads of fun drawing with light!