• This lesson will take you through using the Wrapper Material in V-Ray for Maya
  • The information centers around the VRayMtlWrapper and introduces V-Ray Object Properties and global rendering overrides
  • This 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            

Additional resources

 


Overview


Goal - In this lesson you will learn how to set up matte surfaces with V-Ray

Objective – We will incorporate the V-Ray Wrapper Material into our 3D scene.             

Outcome  - You will be able to apply the VrayMtlWrapper to objects in our scene and understand how to create special overrides in your scene. You will also understand how to use V-Ray Wrapper overrides for better placing a CG object into a live action background.     

 


 

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 the VRayMtlWrapper and render overrides in general:

  • Matte surface
    • Replaces the base material in the MtlWrapper with the scene’s existing background
  • Environment Override
    • Replaces the Maya environment settings with user-selected V-Ray options for a multitude of effects
  • Object Properties
    • New set of V-Ray specific rendering attributes that are assigned to an object directly
    • Allows customizable render settings on a per object basis
 

2. MtlWrapper Overview


  • Can be used to specify additional surface properties per material
    • Can change the behavior of an object in the render (for example, GI receiving and casting, alpha contribution, etc.)
  • Base Material
    • The surface’s intended material
  • Additional Surface Properties
    • Settings used to manipulate GI and Caustic characteristics
  • Matte Properties
    • Settings used to adjust Alpha and Shadow characteristics
These properties are also available by using a VRayObjectProperties node on the object instead (or in tandem with the Material Wrapper)
 

 

3. VRayObjectProperties Overview


  • VROPs can be assigned directly to geometry nodes with additional control
  • Used to specify additional object attributes and render functions on a per object basis
    • Visibility, GI calculation overrides, Shadow Receiving/Casting, etc.
    • To add this node to selected object(s), use the command Apply Single (or Multiple) object properties node from the Create > V-Ray menu or the V-Ray shelf
  • Additional Surface Properties
    • Settings used to manipulate GI and Caustic characteristics
  • Matte Properties
    • Settings used to adjust Alpha and Shadow characteristics

 

 
4. Render Settings Overrides


You can also create override on a global basis for the scene through Render Settings

Environment section

  • Override Environment
    • Turn On to override the default Maya environment and render with different V-Ray options
    • For example, have a different reflection environment than your GI environment
    • Useful for using higher resolution maps for crisp reflections and lower resolution for GI calculation
  • Background texture
    • A color or map used as a background during rendering that need not effect GI or reflections, etc.
  • Show in viewport
    • Similar to image plane on a camera

 

 

5. Material Wrapper


 

a) Matte Surface
  • Makes the material appear as a holdout material, which shows the background, instead of its base material
  • The Base Material is still used to calculate GI, caustics, reflections, etc. for compositing use but does not appear in the render otherwise

 

Matte Surface: Off

Matte Surface: On

Alpha Channel

 


b) Alpha Contribution
Determines the appearance of an object in the alpha channel of the rendered image
    • A value of 1.0 means the alpha channel will be derived from the existing transparency of the base material
    • A value of 0.0 means the object will not appear in the alpha channel at all and will show the alpha of any objects behind it
    • A value of -1.0 means that the transparency of the base material will cut out from any alpha from the objects behind
    • Matte objects are typically given an alpha contribution of -1.0 to make sure they cut out of the alpha for compositing use

 

 

Alpha Contribution of floor: 1

Alpha Contribution of floor: 0

Alpha Contribution of floor: -1

 

c) Shadows
  • Makes shadows visible on the matte surface
  • Popular use of the Material Wrapper to better integrate CG objects into a live action background

 

Shadows: Off

Shadows: On

Shadows: On (alpha)

 

d) Affect alpha
  • Makes shadows affect the alpha contribution of the matte surface
  • Areas in perfect shadow will produce white alpha, while completely un-occluded areas will produce black alpha
  • Note that GI shadows (from skylight) are also computed, however GI shadows on matte objects are not supported by the Irradiance Map and Light Cache GI engines, when used as primary engines

 

 

Shadows: On

Affect alpha: Off

Affect alpha: On



Conclusion




a) Matte surface
  • How we make our background blend with our CG elements

b) Environment Override

  • Allows you to have different environments considered for the calculation of GI, Reflections and Refractions    

c) Object Properties                                 

  • Instead of global render settings or per material (like the mtlWrapper), settings on a per object basis

 


Demonstration



Time to see it work! 

Watch while I demonstrate how to create and adjust a V-Ray Material Wrapper on a ground plane in our scene.

             

 


Activity



Time to do it yourself!

Now it’s your turn!! Use the provided scene file to recreate the cinematic look as you have seen me demonstrate. 
We have also provided a final scene for your reference.
  
 
Used values:
mtlWrapper for the table surface:
  • Matte Surface On
  • Alpha Contribution set to -1
  • Shadows On
  • Affect Alpha On

 

      


Additional resources


Find more training resources listed below: