2. V-RAY FOR 3DS MAX Global Illumination for Interior Scenes

3. LESSON INTRODUCTION Orientation
• This presentation covers the setting up of GI for an interior scene using Skylight portals and the V-Ray Quick Settings
• This lesson topic is approximately 35 minutes in length
• This presentation covers all 3 Learning Cycles – Lecture, Demonstration and Activity

4. GI FOR INTERIORS
• Objective – We will optimize the calculations of Global Illumination for an interior scene
• Outcome – You will be able to optimize the quality and speed of the GI calculations for an interior scene
Artwork by Name

5. TERMINOLOGY
• These are some of the terms to be aware of when thinking about Global Illumination
Global Illumination – a method for gathering light that comes indirectly to the scene. This may be bounced light or light coming from the environment
Primary Bounce Engine – this is the GI engine used to calculate the first bounce of indirect light. It has to be very precise because it has a great contribution to the final illumination in the scene
Secondary Bounce Engine – this is the GI engine used to calculate all bounces of light after the primary bounce. Because we need to calculate multiple bounces of light here, precision is not as important as speed.
Render elements – in CG an image can be split into its composing elements i.e. reflections, refractions, direct and indirect light etc.
Skylight portal – a special mode of operation of the V-Ray Light, which allows us to gather illumination from the environment and shine it into an interior scene

6. GI FOR INTERIORS Basics • Makes the image more realistic
• The contribution of GI is much more obvious in a closed space where light bounces a lot.
• Lots of secondary bounces must be traced to get an accurate GI solution
• It is much harder to create a good GI solution for interiors, especially when light is coming through windows. Many more rays need to be traced because only few of them will go through the windows and hit the environment map
• Skylight portals allow us to optimize the process by shining direct light from the environment through the windows.

7. GI FOR INTERIORS GI Engines
• Light Cache must be used as a Secondary bounce engine because it is capable of tracing multiple secondary light bounces very quickly
• Irradiance Map is the default choice for Primary Bounce engine. It is both fast and reasonably accurate and does a good job in most cases.
• Brute Force is the most accurate engine that we can use for Primary Bounce engine but it’s also a bit slower that the Irradiance Map. We will only use it if there is a lot of small detail in the scene that

8. GI FOR INTERIORS Skylight Portal
• The V-Ray Light, when switched to Plane or Disk Type, can operate as a Skylight Portal.
• In this mode the color and intensity of the light are calculated automatically
• V-Ray samples what is behind the light (environment, bright objects, etc.) and then shines direct light with the correct color and intensity.
• This makes it much easier to calculate GI in an interior scene where light is coming from the windows.
• Simple – when this checkbox is enabled V-Ray samples the environment behind the Light. (all geometry is skipped)

9. GI FOR INTERIORS Quick Settings
• Allow us to easily control quality vs render times ratio with a few sliders
• GI presets for different scenarios: Exterior, Interior, VFX and Studio
• GI drop down allow us to chose between accurate or fast combinations

10. GI FOR INTERIORS BF + LC Accurate
• Very accurate because of Brute Force
• Light Cache gathers may secondary bounces of light
• GI Quality affect the quality of the Light Cache
• Shading Quality affects the quality of the Brute Force solution and the quality of the illumination generated by the Skylight portals
• AA Quality is used to clear out noise that is due to the anti aliasing of the image

11. GI FOR INTERIORS IM + LC Fast • Fast because of Irradiance Map
• Light Cache gathers may secondary bounces of light
• Shading Quality affects the quality of the illumination generated by the Skylight portals
• GI Quality affect the quality of the Irradiance map and Light Cache
• AA Quality is used to clear out noise that is due to the anti aliasing of the image

12. GI FOR INTERIORS Render Elements
• Can be used to see the contribution of Direct and Indirect Illumination to the final result

13. DEMONSTRATION GI for Interiors
Sit back and watch as I demonstrate how to set up Global Illumination in the scene…

14. ACTIVITY GI for Exteriors
Now it’s your turn. Use the provided scene and handout to set up the Global Illumination …