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Introduction

 

 


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  • This lesson will take you through creating a quick Global Illumination for Exterior scenes
  • The information centers around GI and the V-Ray Quick Settings
  • This lesson topic is approximately 30 minutes in length
  • Lesson covers all 3 Learning Cycles for the Lesson Topic – Lecture, Demonstration, and Activity
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Contents


Overview
Available Materials
Lecture
Demonstration
Activity                                                                                                             

 

Overview


Goal - In this lesson you will learn how properly set up the GI for exterior scenes in order to optimize quality and render times.

Objective - We will learn how to add Global Illumination to an exterior scene                                              

Outcome - You will be able to add GI to your exterior scenes and know the basics of tweaking settings depending on the scene.


Available materials


To set up the lesson follow the links below and download all available materials.

Lesson plan download
Presentation (Lecture) download
Demonstration tutorial download                              
Scenes & Assets download

 

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Lecture



1. Terminology

When we see things in the real world they are illuminated both directly and indirectly. Here’s some terms to be aware of when thinking about Global Illumination.

  • Indirect Lighting
    • When light bounces around and fills in areas that a direct light source can not reach
  • Anti-Aliasing
    • A method of smoothing the edges of render objects to improve the quality of the image
  • Image Sampler
    • An algorithm for sampling and filtering the pixels in your render
  • Ray Distance
    • The length light will travel in a 3D scene to calculate indirect illumination

  

2. Light Bounces


 

  • Light naturally bounces off and around other objects to illuminate things we see
  • The more the light bounces, the more shadows will be filled with light
 
  

3. Global Illumination


 a) V-Ray Quick Settings
  • The V-Ray Quick Settings dialog is an easy way to control the most common aspects of the renderer and to quickly switch between different GI solutions and quality settings
  • It is also intended to give new V-Ray users the ability to set up scenes without worrying about all the different V-Ray options available in the Render Setup dialog
  • Presets help give a good starting point depending on the type of scene

 

 

  • The ArchViz Exterior preset is useful for exterior scenes where there isn’t a lot of bounced light
    • The Manage Presets allows you to save the current settings into the V-Ray presets file or to load a previously saved settings
    • The Settings buttons give you a quick way to jump to the render settings that apply to the area affected by the Quality sliders (GI, Shading, Anti-Aliasing)

To open Quick Settings, click its icon in the V-Ray shelf (shown below)

  • If you do not have the V-Ray shelf, enable it through the Render Settings window, Vray tab under the Vray UI heading by clicking Create/Replace V-Ray Shelf
 
 

 
  

b) Render Elements
  • The info that can be seen by different Render Elements can help us understand more about what’s calculated in the GI part of the render
    • GI – the diffuse surface global illumination (or indirect lighting)
    • Lighting– the diffuse direct surface lighting
 
 
  • Breaking out the direct and indirect lighting can help see what areas are contributing to the final result
 

 

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GI Render

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Lighting Render

 

 

c) V-Ray Quick Settings GI Quality
  • With the BF + BF (accurate) Preset selected, the GI Quality slider adjusts the Brute force Subdivs used when calculating the indirect illumination
    • The other GI presets can be used to change the bounce engines used in the GI calculation of the render
    • The Light bounces changes the Brute force Depth amount

 

 
 

 

d) V-Ray Quick Settings Shading Quality
  • The Shading Quality slider adjusts the Image Sampler’s Min Shading Rate
    • Min Shading Rate controls the number of rays for AA vs. rays for other effects like glossy reflections, GI, area shadows etc.
    • Especially useful with the Progressive image sampler.
    • Higher values mean less time spent on AA, and more calculation time spent on the sampling of shading effects
 

 
  
e) Adaptive Image sampler
  • Threshold - determines the sensitivity of the sampler to changes in pixel intensity
    • Lower values will produce better results, while higher values will be faster, but may leave some areas of similar intensity under-sampled
    • Lower values also helpful when rendering textures with small details or noisy bump maps
 

  


Conclusion



 

a) Indirect Lighting

  • Illumination caused by light rays bouncing off objects in the scene

b) Anti-Aliasing

  • A function used to produce cleaner renders by blurring the edges of an object with pixels in the background

c) Image Sampler

  • A group of settings that help set up the correct Anti-Aliasing settings for your scene

d) Ray Distance                                                                                                                                                                                      

  • The distance a light ray can travel to calculate GI

 


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Demonstration



Time to see it work! 

Watch while I demonstrate how to adjust the GI settings of our render from the V-Ray Quick Settings and the GI section of the Maya Render Settings window.
                                                                                                                                                                                                                                         

 

 


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Activity



Time to do it yourself!

Use the provided scene file to setup GI in the exterior scene of the floating house.
We have also provided a final scene for your reference.
 

 

Dialing in the right values

  • GI Quality at 100%
    • BF subdivs: 64
  • Shading Quality at 50%
    • Min Shading Rate: 32
  • AA Quality at 29%
    • Adaptive Min subdivs: 1
    • Max subdivs: 8
    • (noise) Threshold: 0.005