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Understanding the basics of CG Lighting

Through all my years in the movie making industry I have studied the intricacies of CG Lighting techniques and have come up with the following article to give those just getting started some baseline knowledge on the concepts involved. Hope you enjoy!

Overview

  • Source of Lights
  • Basic Lights
  • Basic Lighting Setup
  • Shadows
  • Imaged Based Lighting
  • Lighting Effect

Source of Lights

Including both natural and artificial sources

sources

This is a list of sources of light. The sun, moon, fire  and artificial source such as light bulbs etc.

 

 Sunlight “Painting” and Sunlight “CGI”

 

In the past, artists observed and mimicked whatever there is in the natural world that they desired to paint. We can find several lighting conditions in the natural world or environments such as the most common and natural phenomena – sunlight. We have here on this second example, a computer generated image using the same sun-lit technique, forcing computer artists to do the same as painters to mimic what is in the environment world.

exp_sunlight_web

 

Candle Light

 

In an example of artificial light, such as light candles or light bulbs a similar challenge forces all kinds of artists including CG artists to follow the same rules of physical lighting. Most of the time using artificial lights helps achieve very dramatic scenery.

candel_light

 

Basic lights

 

We have different ways of achieving these lighting effects. The most common lighting techniques used in any 3d program are spot lights, point lights and directional lights.  With these, we can achieve any result we desire in creating CGI images.

basic_cg_lighting-

 

Key light

A main light. It simulates the sun or moon. It also provide a main shadow on the objects.

key_light

 

Fill light

No direct light. It could be sky or ambient.

fill_lights

 

Rim lights

We use this usually for artistic purpose. It gives the object separation from the background.

rim_lights

All the lights been added

all_lights

 

Basic Lighting Setup

 

This would be a 3d scene showing positioning of lights. The sun light can be placed as you desire but the fill light should come from an opposite angle than the key. For example: If the key is on the left then the fill should on the right. The position of Rim light is behind your subject, opposite from the camera.

 

basic_lighting_setup

 

Shadows

 

Shadows. What are shadows? Shadows are nothing but the absence of light.  As you know, “Shadows and lights”,  cannot live without each other in this world. They are indeed needed in this world to show the way. However, in a less philosophical description, shadows in CG are needed to give a 2D dimensional information such as size and location of the scene. It tells us about lighting conditions such as weather, timing of the day or the importance of story telling.

 

shadow

sha

 

Ambient occlusion

 

It gives a sense of realism in terms of object shape. It is not related to lights or any kind of environment.

ambient

 

 

Image Based Lighting

 

It is a technique to create photo-realistic images based on “High Dynamic Range Images”.  In 1997 a single HDR image was presented to the public by Paul Debevec. This image revolutionized the movie industry allowing us to achieve the most realistic results in the CG world.

imagebase3Dviwer

IBL

 

 

Lighting effects/ volumetric

 

This is an example of godrays. It could be fog, smoke etc…

Lighting_effects

 

The art of CG lighting, I believe, has the same skillset required as any art form. We need to analyze and interpreting our world and surroundings.
Enjoy the art of CG. Thank you.

 

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