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Raytracing Tutorial Wine Glasses
Arnold, Maya Renderer, Mental Ray

raytrace_wine1

Photo

Arnold Renderer

raytrace_wine2

Maya Renderer

Mental Ray Renderer

Revolve a wine glass shape, place it on a plane.

Turn off Color Management

Select Windows->Settings/Preferences->Preferences
Select Color Management
Uncheck Enable Color Management
Select Save



Render an image to the Render View
In the persp window
     Select View->Camera Settings->Resolution Gate
     Uncheck View->Camera Settings->Gate Mask
This will let you see how the image will be cropped.

Click the Render View icon upper right render_view
Click the Render the Current Frame icon to render an image  render_current_frame_render_view



Rendering with Arnold
Find a photograph of a glass you like for reference.

hypershade  Windows->Rendering Editors->Hypershade

In the hypershade window, add an Arnold aiStandardSurface.

Model a wine glass using Surfaces->Revolve

Select the wine glass.
Pre Maya 2019: Use the Attribute Editor, turn off Opaque under Arnold.
Use the Hypershade window, with the wine glass selected.
Right mouse key over the shader ball, select Assign Material to Selection.

Click the aiStandardSurface shader ball.
     Under Base
          Set Weight to 0    (default .8)
          Set Metalness
to 0     (default 0)
     Under Specular

          Set Roughness to (default .2, 0 will render faster, add fogginess to the glass)
          Set IOR (Index of Refraction) to 1.5, or 1.1 for thin glass  (default 1.5)
          Set Aristrophy to .5   (default 0)
     Under Transmission
          Set Weight to 1 (default 0, this makes the shader transparent)



Lights
Use Arnold->Lights->Area light
Scale the light tall and thin, following the proportions of the wine glass.

In the Attribute Editor

     Set the Exposure to 8
     Uncheck Cast Shadows
     Uncheck Cast Volumetric Shadows

Add an Arnold->Lights->Skydome light for ambient light
     Set the color to 50% grey
     Uncheck Cast Shadows and Cast Volumetric shadows

Use a Create->Lights->Point Light
     Under Shadows
          Change the Shadow Color to 50% gray
     Under Arnold
          Set the Exposure to 8
          Uncheck Cast Volumetric Shadows

*Note:
When rendering transparent and refractive surfaces in Arnold, the normals of the geometry need to face in the right direction.



Invisible Shadow Caster

Duplicate your wine glass with Ctrl D

In the Attribute Editor
Make sure the 2nd tab is selected in the Attribute Editor.
     Under Render Stats
          Uncheck everything except Casts Shadows
     Under Arnold->Visibility
          Uncheck everything except Casts Shadows
         

Assign a Lambert Shader



Render Settings Arnold
Press this icon upper middle right srender_settings

With these settings below, your scene will render faster with a preview quality.
Under the Arnold Renderer
tab:
Under the Sampling arrow:
   Set Camera (AA) to 3+   (default 3 removes grain)
   Set Diffuse to 2   (default 2)
   Set Specular to 1   (default 2)
   Set Transmission to 2   (
default 2, controls transparency and takes away grain)
   Set SSS to 1   (
default 2)
   Set Volume Indirect to 0   (
default 2)

Under the Ray Depth arrow
   Set Total to 8   (
default 10)
   Set Diffuse
to 1   (
default 1)
   Set Specular
to 1   (
default 1)
   Set Transmisssion
to 8   (
default 8)
   Set Volume
to 0   (
default
0)
   Set Transparency Depth
to 3   (effects the shadows,
default
10)
Click
Close to close the window

Count the number of glass surfaces overlapping to determine the Total and Transmission.






Rendering with Maya Software Renderer

hypershade  Windows->Rendering Editors->Hypershade
In the hypershade window, add a Phong Shader .
Select the wine glass.

Use the Hypershade window, with the wine glass selected, right mouse key over the shader ball, select Assign Material to Selection.

Double click the
Phong shader ball to see the attributes..
Adjust Color to 50% grey.
Adjust Transparency, double click on the black color box to bring up the menu.
  
In HSV mode input .9 as the value (V)

Under Specular Shading:
Input Cosine Power 100
Djust Specular Color to white
Input Reflectivity .1

Under Raytrace Options:
Check Refractions
Input Refractive Index 1.3
Input Refraction Limit 8
Input Reflection Limit 1



Lights
To get highlights, use Create->Lights->Area light with a tall and thin scale, following the proportions of the wine glass.
Under Raytrace Shadow Attributes
   Check Use Raytrace Shadows
   Increase Shadow Rays to 20 or more only for Area Lights, this gets rid of the noise.
   Ray Depth Limit 2

Add Create->Lights->Ambient light  for ambient light, place diagonally opposed to the area light.

Set the color to 50% grey

Add a giant sphere for the background.


Press this icon upper middle right srender_settings
Change Rendering Using to Maya Software
Under the Common tab:
Under the Image File Output
arrow:
Choose Image format: Tiff

Under Maya Software tab:
Under Raytracing Quality
  
Check  Raytracing
  
Input Reflections 1
  
Input Refractions 8
  
Input Shadows 2
  
Input Bias .02 This will make round objects look less jaggy.


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