Digital Cinematography
Arts Col 752		  

 


Types of direct light sources in Maya

A point light shines evenly in all directions from an infinitely small point in space. Use a point light to simulate an incandescent light bulb or a candle flame, where surrounding objects on all sides may need to be illuminated.

Point lights are a good start for an interior key light, and fill lights for either interior or exterior scenes.
A spot light shines a beam of light evenly within a narrow range of directions that are defined by a cone. The rotation of the spot light determines where the beam is aimed. The width of the cone determines how narrow or broad the beam of light is. You can adjust the softness of the light to create or eliminate the harsh circle of projected light. You can also project image maps from spot lights.

Use a spot light to create a beam of light that gradually becomes wider (for example, a flashlight or car headlight).

Use a directional light to simulate a very distant point light source (for example, the sun as viewed from the surface of the Earth).

A directional light shines evenly in one direction only. Its light rays are parallel to each other, as if emitted perpendicular from an infinitely large plane.

Directional lights are an ideal key light to start with for an exterior daylight scene, or as a sunlight coming through a window. They can sometimes be used effectively as fill lights with low intensity - but use with care so as not to make the overall lighting look flat.

An ambient light is commonly used to set the global level of illumination in the scene, raising any shadowed areas above black. However, it tends to flatten the scene, and the three types of lights above are recommended instead for ambient light fill effects with better creative control.

In Maya, ambient lights have no effect on the specular component of surfaces (note you can turn off specular on other lights to get the same result). Additionally, Maya adds an "ambient shade" attribute that blends between the global ambient effect and the effect of a point light (the default being a 50/50 blend).
 
An advantage of using a volume light is that you have a visual representation of the extent of the light (the space within which it is bound). The falloff of light in the volume can be represented by the color ramp (gradient) attribute in Maya, which prevents the need for various decay parameters, and also provides additional control. The color gradient is also useful for volume fog.

You can achieve different effects with light direction. Outward behaves like a point light and Downward acts like a directional light. Inward reverses the light direction for shading, giving the appearance of inward illumination. When using shadows with Inward light direction you may get unexpected results. In all cases the light shape dictates the extent of the light.
In Maya, area lights are two-dimensional rectangular light sources. Use area lights to simulate the rectangular reflections of windows on surfaces. An area light is initially two units long and one unit wide. Use Maya's transformation tools to resize and place area lights in the scene.

Compared to other light sources, area lights can take longer to render, but they can produce higher quality light and shadows. Area lights are particularly good for high-quality still images, but less advantageous for longer animations where rendering speed is crucial.

Area lights are physically based—there is no need for a decay option. The angles formed with the area light and the point that is shaded determine the illumination. As the point moves further away from the area light, the angle decreases and illumination decreases, much like decay.