Enhancing Realism Part 3:
Indoor Character Portrait Lighting

There are a number of techniques which can be used to enhance realism for indoor character portrait type renders.  The key is to establish a good lighting setup which balances the light and shadow contribution from indirect lighting with additional direct lighting
Three Point Lighting:  The most common type of lighting setup used in portrait photography is called "Three Point Lighting".  This setup uses three lights: A Key Light which is the main light source and casts the only shadows in the scene, a Fill Light which is half the intensity of the main light source and is used to soften or counteract shadows. and a Rim Light used to accentuate the edges or outline of the character.  Fill Lights and Rim Lightsin CG are typically set with shadows turned off.  The Key Light which casts the main shadows is set to a 50% shadow intensity with 5% softness.  The Key Light is positioned at a 30 degree to 60 degreee angle from the centerline of the figure.  The Fill light is then positioned directly opposite of the Key light.  The Rim Light is positioned to the rear of the figure.  If your CG system does not have the capability to render with indirect lighting, then the Three Point Lighting system is the best way to go.

Indirect Lighting:  Most CG systems have the ability to utilize indirect lighting models such as Ambient Occlusion, Global Illumination, or Radisoity.  These indirect lighting models can add much greater realism but in general, they must be extended with direct lighting to produce a good result.  The image to the left was generated with 100% Global Illumination with no addtional direct light sources.  While the shadows look quite nice, the image lacks contrast and specular highlights which is quite typical when using 100% Indirect Lighting.
Two Point Indirect Lighting:  A hybrid approach which works quite well for Indoor CG character renders is what I call Two Point Indirect Lighting which uses Indirect Lighting as the Key Light along with Fill and Rim direct lights.  Indirect Lighting is typically set to a balance of 50% to 80% versus Direct Lighting.  This leaves the remaining 20% to 50% lighting to the Direct Fill and Point lights to bring out specular hightlights and to soften the shadows of the Indirect Lighting.