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Introduction


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  • 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
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Contents


Overview
Available Materials
Lecture
Demonstration
Activity                                         
Additional resources       
                      


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Lesson Overview


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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

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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                                       

 


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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

 

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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

 

 

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Without Motion Blur

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With Motion Blur

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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

 

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Shutter speed: 10

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Shutter speed: 20

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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

 

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Shutter speed: 10   ISO: 20

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Shutter speed: 40   ISO: 80

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 h) Depth of Field

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

 

 

 

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Without Depth of Field

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With Depth of Field

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 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

 

 

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Without Aperture Map

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With Triangular Aperture Map

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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

 

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F-number: 2.0

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F-number: 5.5

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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

 

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F-number: 2.0   ISO: 100

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F-number: 5.5   ISO: 800

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 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

 

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Focal length: 50mm

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Focal length: 35mm   (camera dollied in)

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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                                                                     

 


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Demonstration



Time to see it work!

 

  

 


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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.

 

                                   

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additionalresources
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Additional resources


Find more training resources listed below: