Introduction


  • This lesson will take you through creating and using V-Ray Render Elements for compositing a beauty pass
  • This information centers around the Render Elements you can create using V-Ray
  • The lesson topic is approximately 30 minutes in length
  • Lesson covers all 3 Learning Cycles for the Lesson Topic – Lecture, Demonstration, and Activity

Contents


Overview
Available Materials
Lecture
Demonstration
Activity                                                                                          


Overview


Goal - By the end of this lesson you will know the workflow for splitting an image into its components

Objective – We will render several Render Elements and use them to create a beauty pass in compositing                                                    

Outcome – You will understand how to separate your renders into Render Elements to produce a professionally composited image



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                                       

 


Lecture



1. Terminology

Here’s some terms to be aware of when thinking about Render Elements.

a) Pass
  • A “once-over” on the rendering to produce a specific effect. You can think of a pass as a “sweep” through the image to do one specific thing.
b) Render pass
  • A pass that renders the entire image and stores one or more elements of the scene, for example just the lighting or just the reflections.
c) Render Element
  • The results of a render pass that can be combined in a post process to adjust the final image
d) Compositing
  • The combining and adjustment of Render Elements and/or other elements such as live footage or background plates
e) Beauty pass
  • The combining and editing of certain Render Elements to create a traditional rendered image

2. V-Ray Render Elements


 а) For a high-end work such as feature films, rendering straight out of Maya/V-Ray is usually never enough control to get the desired look

  • Rendered image might need adjustment to match live-action lighting, color temperature, etc.
  • Director might want to try different sky backgrounds, combinations of landscape elements, etc.
  • Common adjustments include color correction, improvement of contrast, adding or enhancing Lens Effects
  • Making changes to Render Elements is faster and easier than re-rendering

 

 



 


 



 

 

b) Compositing with Render Elements provides the solution
  • Render elements layered on top of one another to generate final image
  • Render Elements can be adjusted individually to produce a certain look

 

c) Compositing of Render Elements is done outside Maya/V-Ray, in a compositing program
  • Software programs designed for compositing include After Effects, Nuke, Fusion, Photoshop
  • Render Elements are exported from V-Ray and imported into compositing software

 

 



 



 



 

 

d) A Render Element is a regular 2D image, where each pixel has RGB numerical values
  • 3D model and parameters are not exported, just an image!

 

e) In compositing, each Render Element is usually “added” or “multiplied” with previous layers
  • In compositing, black = 0 and white = 1
  • Colored pixel + black pixel = no change
  • Colored pixel + white pixel = brighter colored pixel (up to pure white pixel)
  • Colored pixel x black pixel = black pixel
  • Colored pixel x white pixel = no change

f) All Render Elements can be exported together in one multi-channel EXR file, or…
 
g) Each Render Element can render in its own image file for layering in compositing software

 

3. Render Elements Compositing Workflow


a) Add Render Elements in Render Settings window
  • Once added, elements automatically available in VFB for each rendered image
  • Save as EXR file for compositing
  • EXR file is a collection of Render Elements (2D images)

 

b) Composite Render Elements in programs like After Effects
  • Using plugins, multi-channel EXR files open as layers, one layer per Render Element
  • Render Elements can be adjusted to create different effects
  • Render beauty pass as final image

 

c) Alpha Render Element
  • Opacity of scene elements
  • Anti-aliased edges in grayscale for smooth blend with other images such as background plate
  • Useful for trying different backgrounds

 


 

 

Alpha Render Element

Beauty Render

 

 

d) Atmosphere Render Element
  • Atmospheric effects such as fog
  • Render element can be used to punch up or tone down fog effect in beauty render

 

 

Atmosphere Render Element

Beauty Render

 

 

e) Background Render Element
  • Just the background as viewed behind solid objects
  • Used for color correction on background alone

 

 

Background Render Element

Beauty Render

 

 

f) Global Illumination Render Element
  • The colors rendered as a result of GI
  • Provides main coloration for beauty render
  • Used for color correction on all objects in scene at once
    • Example: Increase saturation to give a surreal look

 

 

GI Render Element

Beauty Render

 

 

 

g) Lighting Render Element
  • Colors rendered as a result of light sources directly striking objects in scene
  • Used to change color or temperature of light directly from light sources
    • Example: Shift colors toward yellow for a “sunnier” look, or toward blue for a “moonlight” look

 

 

Lighting Render Element

Beauty Render

 

 

 

h) Reflect Render Element
  • Rendered colors represent location and color of reflection present in scene
  • Can be used to punch up or tone down reflection
    • Example: Brighten reflections to make objects seem smoother or more metallic

 

 

Reflect Render Element

Beauty Render

 

 

i) Refract Render Element
  • Rendered colors represent refraction present in scene
  • Used to enhance refraction effect
  • Example: To make refraction more visible or noticeable in scene

 

 

Refract Render Element

Beauty Render

 


j) Specular Render Element
  • Specular highlights only
  • Used to punch up or tone down specular highlights
    • Example: Brighten specular highlights to give impression of very bright lights offscreen

 

 

Specular Render Element

Beauty Render

 

 

k) Saving the render elements
  • Use the save button in the VFB toolbar
  • Saves directly to an OpenEXR file containing all Render Elements specified in Render Settings
  • Can also save each elements individually

 

 

Conclusion



a) Render Elements
  • Give you the ability to adjust the rendering without re-rendering
b) EXR file
  • Collection of Render Elements
c) Compositing
  • Combining and adjusting Render Elements
d) Beauty pass
  • The results of the combination of Render Elements

 

                           


Demonstration



Time to see it work!

Watch while I demonstrate how to set up and save Render Elements

 

 

                              

 


Activity



Time to do it yourself!

Use the provided  scene file to set up and save Render Elements

 

 

 

 

Practice workflow

  • Choose Render Elements in Render Settings window
  • Render to VFB
  • Look at Render Elements                         
  • Save to EXR file