Part 1 - Introduction
This Guide is meant to be a starting point for lighting in the CG world. These tips and techniques will be skewed towards a gaming environment with an emphasis on storytelling. There will be information here that has been covered many times before, but hopefully there will be something that sheds some light on how to apply traditional film and illustration techniques to the world of computer graphics.
For our purpose we will be employing a lighting style called "Practical Lighting" This is a technique that uses visible or actual light sources to create the lighting scheme. In film a practical light is any light that is visible on the screen. Because of the third dimension and the ability to explore in game environments, In our case any light source could be a considered a practical light. Lamps, torches, candles, ghosts and of course boiling pots of human flesh can all be practical lights.
I would guess 80% of our lights will be practical lights. This will create a believable environment that comes to life for the player. To augment these practical lights and to have further control over the look of the environment and the player's experience we will also have "Local Spotlights." These lights will make up the last 20% of our lights. Local spots are used to control the brightness of a specific area. This will give explicit control over the visibility of areas, objects and puzzles while still retaining the overall feeling and contrast of an environment. Local lights can also be uses to control the ambient light of a scene.
With the addition of "Radiosity" or Global Illumination we have an opportunity to bring even more subtle, believable and even spectacular lighting to our environments. While there is still some work to be done in figuring out how to incorporate this new feature into our lighting work flow, I am confident and excited in the prospects that it offers. Keep in mind, however, radiosity is still no substitute for a good understanding of lighting and composition.
Part 2 - 3-Point-Setup
Let's talk about traditional lighting set ups. The most popular, if not most common, of light set ups is the 3-point lighting scheme. This setup allows the subject to be modeled by the light. The three lights bring out the subjects dimensionality.
The three types of light are called Key, Fill and Back lights. Each of the three points has a specific function.
This is the main light source in the scene. It is also typically the brightest. Lamps, chandeliers, torches and even the sun would be depicted with the key light. Key lights are most often practical lights. If it is not a practical light placement of the key is often 30-45 degrees of the cameras axis and slightly higher than the subject. We will talk about color in the Quality and Color section.
In this movie you can see Coney lit by a very generic 3-point light set up.
This type of light can be a secondary light source or reflected light. It is commonly the dimmest of the three lights. Fill lights are commonly placed on the opposite side of the cameras axis as the Key light. The color can be complimentary to the color of the key. For example, if the key is warm then the fill would be cool.
This final of the three lights is used to create edges on the subject. Back lights are most often used to enhance the shape of the subject and separate it from the back ground. Most often it is located directly opposite of the camera and is placed above the subject. Because they are often used to create silhouettes or edges of the subject they are also referred to as rim lights, hair lights, or even kickers. In some cases more than one Back light is used to help define the edge of the subject and make it pop from the background.
By placing the Key Light in different positions relative to the subject various moods can be achieved. This will be discussed in more depth in the Time of Day and Mood section. For now let's just look at a couple of common lighting schemes.
A Light that come from below the subject is often referred to as a "Light From Hell." Evil characters are lit this way and it instantly reminds us of flashlights and campfires.
A light that comes from directly above the subject can be really creepy. Whenever eyes are in shadow it gives a strange feeling. A dim fill light can partially reveal the eyes are dark shadow areas.
In this movie three different lighting schemes can be seen. Camera angles used in conjunction with lighting angles go far in creating a specific look for a scene.
A Light that come in from behind the subject is called, you guessed it, a back light. So the Back light takes the place of the key light as the dominate source of light in a scene. This is great for creating a silhouette of a character and creates a mysterious feeling.
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