Introduction


  • This lesson will take you through using V-Ray RT in different ways
  • The information centers around rendering and visualizing changes in a scene using RT
  • This lesson topic is approximately 15 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 - This lesson will give you a general understanding of V-Ray RT and its capabilities and limitations when running on CPUs and GPUs. Additionally you'll be able to optimize the performance of V-Ray RT and set it up to create final renders of single images and animations.

Objective – We will render a scene using RT in a few different ways to get an understanding of when to use RT for your workflow.                         

Outcome – You will be able to efficiently render in near-real time to assess changes and edits in your scene as you make them. 

 

      


                   

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

  • CPU vs GPU Rendering
    • CPU renders on main processor
    • GPU renders on the video card
  • Progressive Rendering
    • Starts rendering the final image quickly for faster feedback – computes the whole image at once, instead of in stages
    • Noisy at first, but the system continually refines the render until stopped
    • Easy to setup, only a few controls to adjust
    • V-Ray’s RT is progressive
  • Interactive Rendering
    • Allows you to edit and adjust your scene while the render is updated with every change you make

 

2. RT Overview


 RT two ways:

  • Used as IPR rendering in Maya (left Image) where it shows in the VFB
  • RT can also be used in a Maya Viewport (right image)
    • In the viewport, select Vray RT as the panel’s Renderer

 

 

  • RT can run on CPU or on graphic card’s GPU
  • Nvidia cards support CUDA
  • Other graphics cards support OpenCL
  • Rendering on GPU offloads the processing and can be faster than the CPU depending on the graphics card

 

 

3. RT Settings


a) Shading Attributes

  • Trace Depth – maximum number of reflection and refraction bounces. If any individual materials have a higher Trace Depth specified, V-Ray will cap them at this global value.
  • GI depth – Number of bounces for GI rays. Lower values decrease render times, but at a loss of accuracy.

b) Rendering Values

  • Max render time (min) – sets a maximum time limit for progressive renders. When this limit is reached, V-Ray will stop the render and output the frame.
    • When rendering animations, you should set this value to allow V-Ray to finish one frame and move to the next once the time limit is reached. Without a value set, V-Ray will continue to refine the single frame until it is manually stopped.
  • Max paths per pixel – This limits the maximum quality of the RT render before stopping and/or moving on to the next image in an animation.

 

 

4. Animation with RT


  • Rendering Animation
    • First, turn on Animation in the Render Settings’ Output tab and set your frame range
    • Next, set a value for either Max render time (min) or Max paths per pixel
    • Then select Render > Render Animation with V-Ray RT

               

 

 

Conclusion



  • RT Rendering is done through IPR window or through a Viewport                                                                             
  • RT rendering is Progressive and gives you a quicker view of the entire image
  • Gives a good ability to preview rendered results as you change your scene
  • Great for changing shaders and or lighting                                                                                                  
  • RT results are identical to production rendering with Progressive sampling mode in Maya Batch                        

 

Demonstration



Time to see it work! 

Watch while I demonstrate how to render this car scene with RT, change colors and other scene parameters
Demonstration tutorial                                       
 

                                            

                                                         

 

Activity



Time to do it yourself!

Now it’s your turn!! Use the provided scene file to change the color of the car and try out different color options.
 

 

Dialing in the right values

  • Start an RT render with IPR
  • Graph the network for the Car_Blend material                                                                               
  • Adjust the Diffuse Color of the Car_Coat material
  • RT will update as you change the colors                                                               

 

                                   

Additional resources


Find more training resources listed below: