The book Illuminated Pixels dives into the topic of Lighting in 3D Environments.
It is a book with a lot of pictures, so my written notes will not be very useful and you definitely should go out and get the book. It is one of the few books that covers this subject.
The book has a very simple premise. When you are lighting you need to think about 3 questions:
- Why are you lighting? (principles of great lighting techniques)
- What are you lighting? (What physical property are you trying to imitate?)
- How are you lighting? (The actual technique on how to get your desired effect)
Most artists only focus on the last question. What techniques are you using to get the goal. However if you take the other two questions into account you truly can achieve great lighting.
Part I: Foundations - (Introduction to the “How”)
Important: Before you start lighting you should have already defined where your position of your camera is. Based on the specific camera position you then start lighting the scene.
When working with lights you want to have a couple of views open
- A view of your Render_Cam (Arnold Render View, with low settings to immediately see the results / Maya View with Lighting enabled)
- A perspective view
- A top view - to get an overview of the positions of your lights
- A view of what the light is looking at
I also have the light editor open, as it makes it easier to select the lights and open “Look through light” views
Spotlights give you an high degree of control. You could imitate a directional light, a point light or an area light by utilizing only spot lights.
The main benefit of using this light is that you can exactly define what is going to be lit by the light.
Spotlights without penumbra do not look realistic. (penumbra, drop-off area between inner cone and outer cone)
- Use for Hard light
- Light something specific
Usually some sort of shape that emits light. It creates a diffuse and soft light. (the size of the Area light has an influence on the emitted light)
- Soft light
(Intensity of the Area light may change depending on the Renderer) A area light that is too small acts like a spotlight, but is very inefficient.
Volume light, Ambient Light (not supported by Arnold)
Beginners mistake to overuse this light. In many cases it should be replaced with a different light type.
- Use for radial shadows
- Watch for Hotspots
Basically you use this light to simulate parallel light-rays, basically the only light source that would have such qualities would be sunlight. Usually the scene will look rather bland when using the light.
- Use the light to flood the scene with light
The easiest way to position a light is to look through selected camera
Area Lights & Point lights are positioned easier while keeping track of the position using an ortographical view.
Ensure that the lights are not placed too close to the subject.
Enables you to link the light to specific objects allowing you to create lights specifically for singular objects. Allows you to illuminate parts of the scene with special lights that do not effect the rest of the scene.
- Use it to exclude light
- Use it to add light
Specular and Diffuse Lights
Unlike real lights you can use separate lights that contribute only to specular or only to diffuse. This allows you to remove distracting specular highlights.
- Do not place lights too close - Placing lights to close to the subjects causes you to have inaccurate lighting and you require additional lights
- Do not use too many lights - increases render time, makes the scene too complex
- Know what each light and shadow is doing (If you do not know what is is doing what is it doing in your scene?)
- Get back on track when needed (Use Isolate selected to figure out what lights are doing)
- Name things
- Only add complexity when needed
- The bigger the ‘cheat’ the more knowledge you need.
First define the aspect ratio of your image. Initially use low resolutions and then over time increase the resolution. Output should be OpenEXR
- Use low quality for test renders
- Use high quality for the final renderer
- Light a still life
- Try out every single type of light
- Create a scene only lit by an area light
- Experiment with your render engines settings to figure out the low-quality and high-quality settings
There are vary many different types of shadows
- Cast Shadow (The typical shadow you think about)
- Contact Shadow (A shadow that is caused by objects that are close to each other) (=> Ambient Occlusion)
Additionally we can talk about the shadow side of objects and about objects that are “in the shadows” are not illuminated.
- Defined by the position of the light
- The size of the Light
- The distance from the object to the object that is receiving the shadow
(A lot of differences between depth map and ray traced shadows)
In Arnold you need to disable the “Opaque” Setting for the transparent object so the color of the object can influence the shadow.
Basically the setting that defines how hard the shadow is. Usually you need to increase the Light samples to get a nice looking blurred shadow.
In reality blur is usually caused by the size of the light. The smaller the light the sharper the shadow.
Changing the blur amount allows you to make the shadow look like as if the light source is bigger than it actually is. (as with a spot light it is a infinite small point you need to define this attribute to get nice looking shadows)
This can be an artistic choice, or a cheat to create the illusion of an uniformly transparent object.
Part II - The Goals of Lighting (The “Why”)
- Establish a setting
- Create a mood
- Direct the eye
- illusion of depth
- Illusion of volume
- Reveal substance
- Maintain continuity
- Integrate elements
- Set visual style
- Create Visual Interest
Establish a setting
Time of Day
Depending on the time of day you will have very different lighting conditions
- Warm red toned direct light
- blue toned indirect light
- Typically mist is associated with the morning making the light diffuse
- Like sunset but cooler => cooler colors
- High contrast
- Strong overhead
- Crisp shadow
Early Evening (“Golden Hour”)
- Warm red/gold light
- Blue indirect light
- Pleasing time of day
- Vivid red-gold direct light
- Deep blue shadows
- Often red
- Low-level blue indirect light
- Moonlight is cool/white
Weather Effects change the type of light that is cast by the sun
- Indoor Lighting: Usually lit with tungsten light bulbs=> warm orange light
- Firelight / Candle light => deep orange, more yellow near the source
- Fluorescent light => light green tint
- Forest light=> Dappled + green tint
Depending on the story there may be an overall look and style the lighting needs to consider.
Create a Mood
Lighting of the scene sets the mood.
You can create visual tension, by increasing the contrasts
- high visual contrasts create a more dramatic image.
- low contrast => playful safe image
Additionally you can create tension by hiding or revealing an element. A chaotically positioned light also can create visual tension. i.e. an upward-pointing light on a persons face.
Color is associated with a lot of things
- Red: dramatic, blood, heat, erotism, danger and power
- orange: stimulating (mostly people either like it or dislike it), orange light is more relaxing and pleasant than green light
- yellow is a happy color
- green is a color of growth and nature (however green flesh tones are sickly)
- cyan is bright and energetic
- blue - peace and tranquility
- purple is mysterious
- white is general and oversimplified (may have various cultural meanings, western pure, eastern, death )
However how color influences us is always based on the context of the image.
- Complementary: Colors opposite of the color wheel => visual tension
- Combination of bright saturated colors => Happy upbeat
- Monochromatic => variations of a single color => lower visual tension
You can use a specific color throughout the entire story to symbolize something specific. You will then associate it with a theme throughout the movie.
- What is happing in the story at that time?
- What should the dominant mood be?
- Is a change in plot important?
- is illustrating the ambience most important?
- What is the overall feeling of the story?
- What are the personalities of the characters in the scene?
- Do any characters get a specific lighting?
- Is there symbolic use of color in play?
Direct the Eye / Composition
- Principle of proximity: Grouping of objects that are close to each other
- Principle of similarity: Grouping of object that have similar properties
- Principle of common fate: the objects are moving with each other
- Principle of continuity: we fill gaps in a structure to complete the form
- Law of figure and ground: we attempt to organize reality into the simplest form possible
Role of lines
Lines are very important in directing the eye and create a structure of an image.
A line between two objects can create an relationship between the two objects A frame around an object can emphasize its importance
A line in between to objects can symbolize a barrier between the objects
Object on a field
Isolated Objects either by brightness or color pop out towards other objects that are similar.
6 Tips on how to focus a shot
- Look for distracting elements (think about what is guiding your view away from that what is actually important)
- Get another perspective (get input from another person, stop working on it for a while, change the position of the camera)
- Change the lighting for a single object (=> light linking)
- Change the materials
- Eliminate technical errors
- Adjust the shot in the compositing phase
Illusion of Dimension
Lighting is an important aspect in creating the three dimensional view of an scene. Missing light => flat scene. The more depth cues, the more sensation of depth you will get.
- Light from the side brings out volume
- Grazing lights bring out texture
- Soft frontal light flattens volume
Providing Cohesiveness and Visual Interest
Light in different scenes should be the same, and maintain continuity
Style can dictate the visual style of lighting.
Creating visual interest requires a good aesthetic sense.
Part III: Properties of Light
When placing a light you need to consider two things:
- Angle of the light
- How far is the light away from the surface
The Angle effects on how the light intensity is effecting the object and how it is shaping the object.
When you place your lights too close to the subject, the shadows of the object start to look strange. The further away the more parallel the shadows become.
Additionally lights placed to close to the subject tend to only illuminate a very specific part of the frame. Thus when you start Animating the characters start walking out of the light. (=> do not just only check a single frame if your lighting is correct)
Additionally closer lights tend to have softer shadows
Our eyes adjust more than we think. Light looses intensity based on the distance of the source. (Attenuation, Quadratic Decay rate) The rate of light change decreases with distance.
Small light that is far away Defined shadows and bring out structure. (Often overused in CG)
Most sources are soft lights Blurry Shadows
When the light is dimmer we do not perceive color as good.
It can be used to simulate a black body - however the temperatures are not always the “paint by numbers” approach to select colors. Lights like fluorescent lights are not on the kelvin scale as they appear more greenish.
Part IV: Technique
The most common light setup:
Key light (Primary light source)
- Primary angle of illumination
- Influences the mood
- Shapes the form
- Provides the most shadows
(30-60 Degrees to the front right of the subject)
- Ist the placement realistic?
- (Does the placement work on every frame of the animation)
- What mood do you want?
- What is the intensity compared to the fills?
- What color is the light source?
- Is the light far or near?
- Does the light have a soft or hard shadow?
Fill light (Fills in shadows)
- Controls contrast
- Influences Mood
Common Key: Fill Ratios TV News 1.5:1 Sitcom 2:1 Drama 4:1 Action Sequence 8:1 Horror 10:1 Film Noir 16:1
Most important aspect of fill is that it is diffuse and soft light. They do not need to add an additional specular highlight.
(opposite the key light) (30-60 Degrees to the bottom left of the subject)
- Visual Intensity is always lower than that from the key light. Placement is usually opposite from the key light, however it is actually just positioned in a way that fills in the shadow areas (sometimes multiple lights are better than a single fill)
Set key:fill ratio early.
- Separates subject from background
- Emphasizes the subject
- Adds depth to the scene
position: behind the subject angled a litte to create a small illumination line (is very far away from the subject)
The rim light should have a loose motivation, like a window in the back of the scene.
Tricks of the Trade
Basically shapes in front of the lamp to create shadows, like from trees.
Image Based Lighting
- Camera Position
Shines in all directions
Imitates a light bulb, or a star
Overused by new lighters. The light is quite inefficient. Most lights should be replaced with Spot lights, to avoid unneeded shadow calculations.
When is using it a good choice
- A Radial Light
if possible replace with spot light
- Watch for Hotspots
- If Shadow are not needed turn them off
- maybe imitate the light with multiple spotlights
About Neal Burger
Neal Burger is a successful entrepreuner. He is the founder of Acme Inc, a bootstrapped business that builds affordable SaaS tools for local news, indie publishers, and other small businesses.