ProVideo Coalition.com: Creating Motion Graphics: Keyframes by Chris & Trish Meyer

The 3D implementation in After Effects is very flexible. You can selectively place some layers in 3D space, and leave others in normal 2D. If you don’t create a camera, the composition reverts to a default camera. If you do create a camera to fly around your 3D layers, you don’t need to create lights – by default, the layers keep their original colors, as if perfectly illuminated. Or, you can add 3D lights to your composition.

Lighting is probably the most subtle and powerful aspect of 3D in After Effects, as it can create wonderfully moody shifts in brightness and color, as well as “automatic” shadows without needing to tweak Drop Shadow effects for each layer. Lighting is also probably the least understood aspect of 3D in After Effects. Therefore, we’re going to spend the next few columns discussing lighting tips and tricks, starting this column with the basics: the differences between – and uses of – diffuse, specular, and ambient lighting effects.

Three Paths to Illumination

Lights have an Intensity property, which controls how bright they are. However, when a layer calculates how brightly it is illuminated, it is adding together up to three different illumination properties – Diffuse, Specular, and Ambient – rather than using just one simple intensity value.

A layer adds together the result of diffuse (top left), specular (top right), and ambient (above left) lighting effects to determine its final illumination (above right). These effects can add up to more than 100%, resulting in blown-out hot spots. Image from Digital Vision – Edge of Awareness.

3D layers react to spot, point, and parallel lights twice: first by calculating the diffuse lighting effect contributed by the light, and then by calculating the specular lighting effect contributed by the same light. Diffuse lighting is the general, overall illumination a light provides a layer. Specular lighting is the highlight or “hot spot” you see on shiny surfaces. Specular lighting effects tend to have a sharper “falloff” than diffuse lighting, meaning that the amount of illumination tapers off more quickly as you move away from the center of the resulting hot spot.

Just how strong these lighting effects are depend not just on the light’s Intensity value, but also the layer’s Material Options, the angle between the light and the layer (directly facing the light results in the strongest illumination), and the angle between the layer and the camera (as light rays need to be bounced from the light by the layer to the camera in order to have an effect).

And then there are ambient lights. These illuminate 3D layers evenly, without worrying about falloff or the relative positions of layers, lights, and the camera. They make useful “fill” lights, adding evenly to the illumination of every pixel of a layer without worrying about aiming a light to hit the troublesome dark areas of a layer.

It Takes Two to Tango

The next concept to understand about lighting in After Effects is that the end result is not controlled just by the light: The Material Options of the layers receiving the light are at least as important, as they interact with the light’s own Options. Some users leave the Material Options at their defaults and try to achieve their desired result by manipulating just the lights – but by doing so, you’re tying one arm behind your back.

To reveal a layer’s Material Options, select it in the Timeline window and type AA (two A’s in quick succession). You will see parameters for Ambient, Diffuse, and Specular, which control the balance between the three types of illumination we just discussed. Ambient defaults to 100%, which means it accepts the full power of any ambient-type lights you have added to a comp. If you don’t want a layer to receive ambient illumination, reduce its Ambient Material Option to zero.

A layer’s Diffuse and Specular parameters default to 50% each. However, you do not need to keep these two properties in perfect balance. If you don’t want a hot spot or glare, and only subtle lighting falloff, reduce the layer’s Specular parameter, and crank up its Diffuse parameter. On the other hand, if you want a layer to seem very hard or metallic with bright hot spots, crank up its Specular parameter, and optionally reduce its Diffuse parameter.

What if you have a layer or two that you want to be perfectly illuminated, regardless of how lights are interacting with the other layers in a comp? The simplest approach is to switch its Accepts Lights parameter to Off. This doesn’t mean the layer goes dark; the result is the same as if there were no lights in the composition (resulting in default illumination), but only for this layer.

Monday, September 02, 2002

Blinded by the Light

3D lighting in After Effects can be powerful, subtle…and confusing.

Three Paths to Illumination

A layer adds together the result of diffuse (top left), specular (top right), and ambient (above left) lighting effects to determine its final illumination (above right). These effects can add up to more than 100%, resulting in blown-out hot spots. Image from Digital Vision – Edge of Awareness.

It Takes Two to Tango