Introduction


  • This lesson will take you through adding Motion Blur and Depth of Field to our V-Ray Physical Camera
  • The information centers around vrayPhysicalCamera extra attributes
  • This lesson topic is approximately 40 minutes in length, with two Activity Cycles
  • Lesson covers all 3 Learning Cycles for the Lesson Topic – Lecture, Demonstration, and Activity

 

 

Contents


Overview
Available Materials
Lecture
Demonstration
Activity                                         
Additional resources       
                      


Lesson Overview


Goal - Develop a more realistic and photographic render of our toy train scene with the V-Ray Physical Camera

Objective – We will be able to customize the Depth of Field and Motion Blur effects of the V-Ray Physical Camera for your 3D scenes                                       

Outcome – You will understand the basics of the V-Ray Physical Camera and how to apply Motion Blur and Depth of Field to take it’s realism even farther

 


 

Available materials


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

Lesson plan download
Presentation (Lecture) download
Demonstration tutorial 1 download
Demonstration tutorial 2 download                                                          
Scenes & Assets download                                       

 


Lecture



1. Terminology

The V-Ray Physical Camera is based on a real-world camera so the concepts of photography apply. Here’s some terms to be aware of when thinking about the Physical Camera

 
  • Aperture
    • The hole in a camera lens that allows light to travel through to the inside of a camera
      • Normally referred to by the F-Stop or F-number
  • Bokeh (pronounced BOH-Kay)
    • The way a lens renders out of focus points of light
  • Shutter Speed (or Exposure Time)
    • The length of time when the film or digital sensor inside the camera is exposed to light
      • The camera’s shutter is open to take a picture
  • ISO (International Standards Organization)
    • A camera’s sensor (or film) sensitivity to light, which can help balance effects during the exposure process

2. Physical Camera

a) Aperture

  • Referred to as F-number in V-Ray Physical camera
  • The opening in the camera lens that allows more or less light to pass through into the camera
  • The smaller the opening the smaller the amount of light in the exposure
  • Plays a huge role on Depth of Field
    • The larger the opening (smaller F-number) the shallower the focus area is in depth
    • The smaller the opening, the more distance between objects that are still in focus

 

 

b) Bokeh
  • Most visible around small background highlights
  • The shape of the bokeh is effected by the number of blades in the lens that make up the aperture
  • Normally seen in macro or long telephoto lenses because of the shallow Depth of Field

 

 

 

 

c) Shutter Speed
  • The amount of light that reaches the film or image sensor is proportional to the exposure time
    • 1/500th of a second will let half as much light in as 1/250th
  • Plays a huge role on Motion Blur
    • Faster Shutter Speeds can capture fast moving objects with less motion blur
    • Slower Shutter Speeds allow more light into the camera during the exposure process

 

 

d) Physical Camera Overview
  • To convert an existing Maya camera to a V-Ray Physical Camera, we add the Physical Camera Attribute from the menu in the Attribute Editor
    • The camera’s shape node must be selected
  • This will add Extra V-Ray Attributes to the bottom of the Attribute Editor
    • Camera is not a V-Ray Physical camera until the checkbox Treat as VRay Physical camera is Enabled
  • The Camera settings (extra attributes) overrides some of the Camera settings from the V-Ray Render Settings
    • These settings control the way geometry is projected into the image
    • Allows each camera to have different render settings

 

 

  • F-number – determines the width of the camera aperture
  • Shutter speed – the speed of the camera shutter in inverse sec.
    • If the shutter’s speed was 1/30s the value of the parameter would be 30
  • ISO – determines the film power (sensitivity)
    • Smaller values make the image darker, larger values make it brighter
  • Lens Shift – enter values to shift the lens to mimic real life Tilt-Shift lens effects, which is particularly popular in architectural photography
  • Aperture Map – this attribute allows you to map a custom shaped aperture for your camera for more advanced control over the Bokeh shape

 

 

е) Motion Blur
 
  • The size/amount of the motion blur is determined by the speed of the moving object itself as well as the Shutter speed of the camera

 

 

 

Without Motion Blur

With Motion Blur

 

 

f) Shutter Speed
  • Determines how long the camera will be open to expose an image
    • The longer this time is (small shutter speed value) – the more blurry the motion will be
    • In reverse - if the shutter speed is shorter, fast motion will appear more frozen in place

 

 

Shutter speed: 10

Shutter speed: 20

 

 

g) ISO
  • Determines the sensitivity (brightness) of the image
    • If we increase the Shutter speed to freeze the train (mostly) in it’s tracks, we have to increase the ISO to keep the exposure at the same level

 

 

Shutter speed: 10   ISO: 20

Shutter speed: 40   ISO: 80

 


 h) Depth of Field

 
  • The strength of the depth of field effect depends on the aperture size

 

 

 

 

Without Depth of Field

With Depth of Field

 


 i) Bokeh Effects

 
  • Shape of out of focus highlights is affected by the aperture shape
  • Number of blades and blade rotation
  • Aperture Mapping
    • Adds a texture to aperture shape
    • Can also affect exposure level due to any darkness in the map

 

 

 

Without Aperture Map

With Triangular Aperture Map

 

 

j) F-number
  • Lowering the F-number value will narrow the area of what’s in focus with Depth of Field
  • Increasing the F-number will allow more of your subject (or the area around it) to be in focus

 

 

F-number: 2.0

F-number: 5.5

 

 

k) ISO

  • Just like with adjusting the Shutter, we can use the ISO setting to correct the exposure when adjusting the F-number
    • Luckily in V-Ray we don’t have to worry about introducing grain or noise when making the camera more sensitive to light, like in the real world

 

 

F-number: 2.0   ISO: 100

F-number: 5.5   ISO: 800

 


 l) Focal Length

  • Smaller focal lengths will expand the area of what’s in focus with Depth of Field
    • In the examples below, the Focal length has been changed from 55mm to 35mm
    • The camera has been translated forward to try to match the position on the front of the train
    • Notice how the tree to the left of the train is much more in focus and he bubbles are more clear

 

 

Focal length: 50mm

Focal length: 35mm   (camera dollied in)

 


Conclusion



a) Aperture
  • Effects not only the exposure but how much is in focus with Depth of Field
b) Shutter Speed
  • Effects not only the exposure but also the strength of the motion blur effect
c) ISO
  • Can help fix/adjust the exposure of a shot when the F-number or Shutter speed changes
d) Bokeh Effects
  • Affected by aperture shape

e) Focal Length                                                                     

 


Demonstration



Time to see it work!

Watch while I demonstrate how to apply Motion Blur or Depth of Field to our V-Ray Physical Camera and how to adjust it’s settings.
Demonstration tutorial Motion Blur
Demonstration tutorial Depth of Field

 

  

 


Activity



Time to do it yourself!

Use the provided scene file to learn how to apply Motion Blur or Depth of Field to the V-Ray Physical Camera and affect the quality with it’s settings.

 

 

1. Motion Blur - Dialing in the right values

  • Treat as VRay Physical camera: Enabled
  • Type: Still camera
  • Focal length: (animated)
  • F-number: 1.4
  • Shutter speed: 15
  • ISO: 30
  • Enable Motion blur: On
  • Progressive Image Sampler type
  • Max. render time: 5 mins.

 

 

 

2. Depth of Field -  Dialing in the right values

 

  • Treat as VRay Physical camera: Enabled
  • Type: Still camera
  • Focal length: (animated)
  • F-number: 1.6
  • Shutter speed: 20
  • ISO: 60
  • Enable Depth of field: On
  • Progressive Image Sampler type
  • Max. render time: 5 mins.

 

                                   

Additional resources


Find more training resources listed below: