Chapter 7: Lighting and Render Settings

Learning Objectives

1. Understand the basic principles and types of 3D lighting
2. Master the use of various light sources in Blender
3. Learn to set up indoor and outdoor lighting scenes
4. Become proficient in using the Cycles and Eevee render engines
5. Master render setting optimization techniques
6. Learn to create realistic lighting and shadow effects

Chapter Focus

Lighting is the soul of 3D rendering, determining the atmosphere, realism, and visual impact of a scene. This chapter will delve into lighting theory and rendering techniques.

7.1 Basic Lighting Theory

7.1.1 Physical Properties of Light

Basic Properties of Light

• Color: The wavelength of light determines its color
• Intensity: The brightness of the light
• Direction: The direction in which light rays travel
• Falloff: The decay of light intensity with distance
• Scattering: The interaction of light rays with a medium

# Lighting Physics Model
class LightPhysics:
    def __init__(self):
        self.wavelength = 550  # nanometers (green light)
        self.intensity = 100   # lumens
        self.temperature = 5500  # Kelvin
        self.falloff_type = 'inverse_square'
    
    def calculate_illumination(self, distance):
        """Calculate the illumination intensity at a given distance"""
        return self.intensity / (distance ** 2)

7.1.2 Lighting Model Classification

Lighting Type	Characteristics	Application	Computational Complexity
Direct Lighting	Light source shines directly	Main light source	Low
Indirect Lighting	Reflected and scattered light	Ambient lighting	High
Global Illumination	Direct + Indirect lighting	Realistic rendering	Very High
Volumetric Lighting	Volumetric scattering effects	Atmospheric effects	High

7.1.3 Color Temperature and Light Color

# Common Light Source Color Temperature Reference
color_temperatures = {
    'candle': 1900,           # Candle
    'tungsten': 3200,         # Tungsten lamp
    'fluorescent': 4000,      # Fluorescent lamp
    'daylight': 5500,         # Daylight
    'overcast': 6500,      # Overcast sky
    'blue_sky': 10000         # Blue sky
}

7.2 Blender Light Types Explained

7.2.1 Point Light

Characteristics: A point light that emits light uniformly in all directions

# Point Light Settings
point_light_settings = {
    'energy': 100.0,          # Light intensity
    'color': (1.0, 1.0, 1.0), # Light color
    'shadow_soft_size': 0.1,  # Shadow softness
    'use_custom_distance': False,  # Custom distance
    'cutoff_distance': 40.0   # Cutoff distance
}

Point Light Applications

• Small light sources like light bulbs, candles
• Fill lighting for indoor scenes
• Special effect light sources (magic orbs, etc.)

7.2.2 Spot Light

Characteristics: A conical beam of light, with control over the angle and edge softness

# Spot Light Parameter Configuration
spot_light_settings = {
    'energy': 100.0,
    'spot_size': math.radians(45),  # Cone angle (in radians)
    'spot_blend': 0.15,             # Cone edge blend
    'show_cone': True,              # Show cone
    'use_square': False,            # Use square cone
    'shadow_soft_size': 0.1
}

Application Techniques:

• Dramatic Lighting: Create strong light and shadow contrast
• Focus Lighting: Highlight specific objects or areas
• Architectural Lighting: Simulate spotlights, car headlights

7.2.3 Area Light

Characteristics: A planar light source that produces soft shadows

# Area Light Setting Types
area_light_types = {
    'RECTANGLE': {
        'size_x': 2.0,        # X-direction size
        'size_y': 1.0,        # Y-direction size
        'shape': 'RECTANGLE'   # Rectangle
    },
    'SQUARE': {
        'size': 1.0,          # Square side length
        'shape': 'SQUARE'
    },
    'DISK': {
        'size': 1.0,          # Disk radius
        'shape': 'DISK'
    },
    'ELLIPSE': {
        'size_x': 2.0,
        'size_y': 1.0,
        'shape': 'ELLIPSE'    # Ellipse
    }
}

Area Light Advantages

• Produces natural soft shadows
• Simulates planar light sources like windows, monitors
• Creates studio-level lighting effects

7.2.4 Sun Light

Characteristics: Parallel light, simulating a distant light source (like the sun)

# Sun Light Configuration
sun_light_settings = {
    'energy': 5.0,            # Sun intensity
    'angle': math.radians(0.533),  # Sun angular diameter
    'color': (1.0, 0.95, 0.8),     # Warm color tone
    'shadow_soft_size': 0.1
}

7.3 Environment Lighting Settings

7.3.1 World Material Configuration

Importance of World Material

The world material not only affects the background but also provides global ambient lighting, making it an important part of the scene's atmosphere.

# World Material Node Settings
world_material_nodes = {
    'background_shader': {
        'type': 'ShaderNodeBackground',
        'color': (0.05, 0.05, 0.1, 1.0),  # Deep blue night sky
        'strength': 1.0
    },
    'environment_texture': {
        'type': 'ShaderNodeTexEnvironment',
        'image': 'hdri_sky.exr',
        'interpolation': 'Linear'
    }
}

7.3.2 HDRI Environment Map

HDRI Selection Guide

HDRI Type	Characteristics	Application	File Size
Outdoor Sky	Natural lighting	Product showcase	Large
Indoor Environment	Soft lighting	Character rendering	Medium
Studio	Uniform lighting	Professional photography	Small
Special Environment	Creative effects	Artworks	Varies

# HDRI Setting Optimization
hdri_settings = {
    'rotation_z': 0.0,        # Z-axis rotation to adjust lighting direction
    'strength': 1.0,          # Environment light intensity
    'saturation': 1.0,        # Color saturation
    'hue': 0.5,              # Hue adjustment
    'gamma': 1.0,            # Gamma correction
    'exposure': 0.0          # Exposure adjustment
}

7.3.3 Sky Texture Node

# Procedural Sky Settings
sky_texture_settings = {
    'sky_type': 'NISHITA',    # Atmospheric scattering model
    'sun_elevation': 0.26,    # Sun elevation angle
    'sun_rotation': 0.0,      # Sun rotation angle
    'altitude': 0.0,          # Observer altitude
    'air_density': 1.0,       # Air density
    'dust_density': 1.0,      # Dust density
    'ozone_density': 1.0      # Ozone density
}

7.4 Classic Three-Point Lighting Setup

7.4.1 Key Light

Role: Provides the main illumination, establishing the scene's tone

# Key Light Settings
key_light = {
    'type': 'AREA',           # Area light
    'energy': 100.0,          # High intensity
    'size': 2.0,              # Large area for softness
    'location': (2, -2, 3),   # 45-degree angle position
    'rotation': (math.radians(45), 0, math.radians(45))
}

7.4.2 Fill Light

Role: Fills in shadow areas, reducing contrast

# Fill Light Settings
fill_light = {
    'type': 'AREA',
    'energy': 30.0,           # Lower intensity
    'size': 3.0,              # Larger area
    'location': (-2, -2, 2),  # Opposite side of key light
    'color': (0.8, 0.9, 1.0)  # Cool color to balance
}

7.4.3 Rim Light

Role: Outlines the object's silhouette, enhancing three-dimensionality

# Rim Light Settings
rim_light = {
    'type': 'SPOT',
    'energy': 50.0,
    'spot_size': math.radians(60),
    'location': (0, 3, 2),    # Back position
    'color': (1.0, 0.9, 0.7)  # Warm rim color
}

Advanced Three-Point Lighting

Depending on the scene's needs, you can add extra lights like background light, hair light, kicker light, etc., to enrich the lighting effects.

7.5 Render Engine Comparison

7.5.1 Cycles Render Engine

Technical Features

• Path Tracing: Physically accurate light calculation
• Global Illumination: Realistic light bounces
• Unbiased Rendering: Theoretically approaches reality infinitely

# Cycles Render Settings
cycles_settings = {
    'samples': 128,           # Number of samples
    'max_bounces': 12,        # Maximum bounce count
    'diffuse_bounces': 4,     # Diffuse bounces
    'glossy_bounces': 4,      # Glossy bounces
    'transmission_bounces': 12, # Transmission bounces
    'volume_bounces': 0,      # Volume bounces
    'transparent_max_bounces': 8, # Transparent bounces
    'use_denoising': True,    # Use denoising
    'denoiser': 'OPTIX'       # Denoiser type
}

Optimization Techniques

Sample Optimization

# Adaptive Sampling
adaptive_sampling = {
    'use_adaptive_sampling': True,
    'adaptive_threshold': 0.01,    # Threshold
    'adaptive_min_samples': 0,     # Minimum samples
    'adaptive_samples': 128        # Adaptive samples
}

Light Path Culling

# Light Path Settings
light_paths = {
    'caustics_reflective': False,  # Disable reflective caustics
    'caustics_refractive': False,  # Disable refractive caustics
    'filter_glossy': 1.0          # Glossy filter
}

7.5.2 Eevee Render Engine

Technical Features

• Real-time Rendering: Fast rendering based on OpenGL
• Screen Space Effects: Efficient approximation algorithms
• Game Engine Level: Suitable for interaction and previews

# Eevee Render Settings
eevee_settings = {
    'taa_render_samples': 64,     # TAA render samples
    'taa_samples': 16,            # TAA viewport samples
    'use_bloom': True,            # Bloom effect
    'bloom_threshold': 0.8,       # Bloom threshold
    'bloom_intensity': 0.05,      # Bloom intensity
    'use_ssr': True,              # Screen Space Reflections
    'ssr_quality': 0.25,          # SSR quality
    'use_gtao': True,             # Ambient Occlusion
    'gtao_distance': 0.2          # AO distance
}

7.5.3 Engine Selection Guide

Scene Type	Recommended Engine	Reason	Notes
Product Rendering	Cycles	Physically accurate	Long render times
Architectural Visualization	Cycles	Realistic lighting	Requires denoising
Character Animation	Eevee	Real-time preview	Lighting limitations
Concept Design	Eevee	Fast iteration	Approximate effects
Game Assets	Eevee	Real-time rendering	Optimize settings

7.6 Advanced Lighting Techniques

7.6.1 Volumetric Lighting Effects

Volumetric Lighting Applications

Volumetric lighting simulates the scattering of light in the atmosphere, often used to create dramatic light beam effects.

# Volumetric Lighting Settings
volume_lighting = {
    'principled_volume': {
        'density': 0.1,           # Density
        'anisotropy': 0.0,        # Anisotropy
        'absorption_color': (1.0, 1.0, 1.0),  # Absorption color
        'scattering_color': (1.0, 1.0, 1.0),  # Scattering color
        'emission_strength': 0.0  # Emission strength
    }
}

7.6.2 Ray Tracing Effects

Reflection and Refraction

# Ray Tracing Material Settings
ray_tracing_material = {
    'use_screen_refraction': True,  # Screen space refraction
    'refraction_depth': 0.1,        # Refraction depth
    'use_backface_culling': False,  # Backface culling
    'blend_method': 'ALPHA_HASHED', # Blend method
    'shadow_method': 'HASHED'       # Shadow method
}

7.6.3 Light Groups

# Light Group Settings
light_groups = {
    'key_lights': ['Key_Light', 'Fill_Light'],
    'rim_lights': ['Rim_Light', 'Hair_Light'],
    'environment': ['HDRI_World', 'Sky_Light'],
    'effects': ['Magic_Orb', 'Fire_Glow']
}

7.7 Indoor and Outdoor Lighting Scenes

7.7.1 Outdoor Daylight Lighting

# Daylight Lighting Configuration
daylight_setup = {
    'sun_light': {
        'energy': 5.0,
        'angle': math.radians(0.533),
        'color': (1.0, 0.95, 0.8)
    },
    'sky_texture': {
        'sun_elevation': math.radians(60),  # Noon sun elevation
        'atmosphere_turbidity': 2.0,       # Atmospheric turbidity
        'ground_albedo': 0.3               # Ground albedo
    }
}

7.7.2 Outdoor Night Lighting

# Night Lighting Configuration
night_setup = {
    'moon_light': {
        'energy': 0.5,
        'color': (0.8, 0.9, 1.0)  # Cool moonlight
    },
    'street_lights': {
        'energy': 50.0,
        'color': (1.0, 0.8, 0.6),  # Warm streetlights
        'falloff_type': 'INVERSE_SQUARE'
    },
    'world_background': {
        'color': (0.02, 0.02, 0.05, 1.0)  # Deep blue night sky
    }
}

7.7.3 Indoor Natural Lighting

Indoor Lighting Principles

• Main light source: Natural light from windows
• Auxiliary light source: Indoor lamps
• Reflected light: Reflection from walls and floors

# Indoor Lighting Settings
interior_lighting = {
    'window_light': {
        'type': 'AREA',
        'size_x': 2.0,
        'size_y': 3.0,
        'energy': 20.0,
        'color': (0.9, 0.95, 1.0)  # Cool daylight
    },
    'ceiling_light': {
        'type': 'AREA',
        'size': 1.0,
        'energy': 15.0,
        'color': (1.0, 0.9, 0.8)   # Warm indoor light
    }
}

7.8 Shadow Control Techniques

7.8.1 Shadow Type Comparison

Shadow Type	Calculation Method	Quality	Performance	Application
Ray Traced	Ray tracing	Highest	Lowest	Final render
Shadow Map	Shadow mapping	Medium	High	Real-time preview
Contact	Contact shadows	Low	Highest	Detail supplement

7.8.2 Shadow Optimization Settings

# Shadow Optimization Configuration
shadow_optimization = {
    'cascade_size': 1024,      # Cascade shadow size
    'high_bitdepth': True,     # High bit depth
    'soft_shadows': True,      # Soft shadows
    'contact_shadows': {
        'use': True,
        'distance': 0.2,       # Contact distance
        'bias': 0.001,         # Bias value
        'thickness': 0.2       # Thickness
    }
}

7.9 Render Optimization Strategies

7.9.1 Layered Rendering

Layered Rendering Advantages

• Flexibility in post-production adjustments
• Reduces re-rendering
• Facilitates problem-solving

# Render Layer Settings
render_layers = {
    'beauty': ['Combined'],           # Main beauty pass
    'lighting': ['DiffDir', 'DiffInd', 'GlossDir'],  # Lighting decomposition
    'utility': ['Normal', 'UV', 'ObjectID'],         # Utility passes
    'effects': ['Emission', 'Environment']           # Effects passes
}

7.9.2 Region Rendering

# Region Render Settings
region_render = {
    'use_border': True,        # Use border
    'border_min_x': 0.25,      # Minimum X
    'border_max_x': 0.75,      # Maximum X
    'border_min_y': 0.25,      # Minimum Y
    'border_max_y': 0.75,      # Maximum Y
    'use_crop_to_border': True # Crop to border
}

7.9.3 Network Rendering

# Network Render Configuration
network_render = {
    'server_address': '192.168.1.100',
    'server_port': 8000,
    'chunk_size': 64,          # Chunk size
    'priority': 50,            # Priority
    'use_compositing': False   # Distributed compositing
}

7.10 Color Management

7.10.1 Color Space Settings

Importance of Color Management

Correct color management ensures color consistency from modeling to final output.

# Color Space Configuration
color_management = {
    'view_transform': 'Filmic',    # View transform
    'look': 'None',                # Look
    'exposure': 0.0,               # Exposure
    'gamma': 1.0,                  # Gamma
    'sequencer_colorspace': 'sRGB' # Sequencer color space
}

7.10.2 Tone Mapping

# Tone Mapping Parameters
tone_mapping = {
    'filmic_contrast': 1.0,    # Contrast
    'filmic_saturation': 1.0,  # Saturation
    'filmic_whitepoint': 1.0,  # Whitepoint
    'filmic_shadows': 1.0,     # Shadows
    'filmic_midtones': 1.0,    # Midtones
    'filmic_highlights': 1.0   # Highlights
}

7.11 Practical Project Cases

7.11.1 Product Showcase Lighting

Goal: Create professional product showcase lighting effects

Key Settings:

1. Key Light: Large area soft light
2. Fill Light: Reduce shadow contrast
3. Background Light: Clean background separation
4. Rim Light: Highlight product edges

# Product Showcase Lighting Settings
product_lighting = {
    'key_light': {
        'type': 'AREA',
        'size': 3.0,
        'energy': 100.0,
        'location': (2, -3, 4)
    },
    'fill_light': {
        'type': 'AREA', 
        'size': 4.0,
        'energy': 30.0,
        'location': (-2, -2, 2)
    },
    'rim_light': {
        'type': 'AREA',
        'size': 1.0,
        'energy': 80.0,
        'location': (0, 4, 3)
    }
}

7.11.2 Architectural Visualization Lighting

Goal: Create realistic indoor and outdoor architectural lighting

Key Techniques:

• HDRI environment lighting
• Sun light simulation
• Indoor artificial light sources
• Material and lighting coordination

7.11.3 Character Lighting Setup

Goal: Create cinematic lighting for 3D characters

Key Techniques:

• Three-point lighting basics
• Skin tone-adapted light color
• Independent hair lighting
• Eye highlight emphasis

7.12 Shortcuts and Workflow

7.12.1 Lighting Related Shortcuts

Shortcut	Function	Use Case
Shift + A	Add Light	Create lighting
Ctrl + L	Select All Lights	Batch adjustment
Shift + L	Select Similar Lights	Adjust similar types
H	Hide Selected	Simplify view
Alt + H	Unhide	Restore visibility

7.12.2 Rendering Related Shortcuts

Shortcut	Function	Description
F12	Start Render	Full image render
Ctrl + F12	Render Animation	Sequence render
F11	Show Render Result	View result
Shift + Z	Toggle Render View	Real-time preview
Z	View Toggle	Display mode

7.13 Troubleshooting

7.13.1 Render Noise Issues

Common Sources of Noise

• Insufficient sample count
• Improper lighting setup
• Overly complex material reflections
• Insufficient indirect lighting calculation

# Denoising Setting Optimization
denoising_setup = {
    'use_denoising': True,
    'denoiser': 'OPTIX',       # Or 'OPENIMAGEDENOISE'
    'denoise_pass': 'COMBINED', # Denoise pass
    'denoising_prefilter': 'ACCURATE',  # Prefilter
    'use_denoising_start_sample': True,  # Start sample
    'denoising_start_sample': 1    # Start sample count
}

7.13.2 Overexposure Issues

# Exposure Control Methods
exposure_control = {
    'method_1': 'Lower light intensity',
    'method_2': 'Adjust world exposure value',
    'method_3': 'Use tone mapping',
    'method_4': 'Add fill light to balance'
}

7.13.3 Shadow Artifact Handling

# Shadow Issue Solutions
shadow_fixes = {
    'acne': 'Increase shadow bias',
    'peter_panning': 'Decrease bias',
    'soft_shadows': 'Increase light source area',
    'cascade_shadow': 'Adjust cascade settings'
}

Chapter Summary

This chapter systematically covered the core techniques of 3D lighting and rendering:

1. Lighting Theory: Understood the physical properties of light and lighting models
2. Light Source Usage: Mastered the characteristics and applications of various light sources
3. Environment Lighting: Learned to use HDRI and procedural skies
4. Render Engines: Compared the pros and cons of Cycles and Eevee
5. Advanced Techniques: Mastered effects like volumetric lighting and ray tracing
6. Practical Applications: Improved practical skills through project exercises

Lighting is a core skill in 3D art, requiring a lot of practice and observation to develop a sense of light and shadow. In the next chapter, we will begin to learn the basics of animation production.

Continuous Improvement

Observe the changes in light and shadow in the real world, analyze the lighting characteristics at different times and weather conditions. This will greatly enhance your lighting design skills.