Basic Cloth Material in Arnold for Maya

Software:
Maya 2018 | Arnold 5

An example of a basic traditional (not scanned) cloth material setup in Arnold 5 for Maya using an aiStandardSurface shader.

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The shading network uses a classic angle dependent color blend to simulate the color of the cloth being washed out at grazing angle of view.

Explanation of the node graph:

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  1. A black and white fabric weave texture that will serve as input for multiple shading channels.
    * This is actually not the best example of such a pattern, and could be replaced with a much better texture.
    cotton grey bump
  2. A remapValue node is used to set contrast to the fabric pattern (reduce contrast in this case) prior to it being multiplied with the fabric colors.
    * Note that only one of the textures RGB channels is connected to the remapValue node since it’s a float (mono) processor and not RGB.
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    * Note that depending on the fabric texture, you may have to design different curves to achieve the right effect.
  3. Two colors are defined with colorConstant nodes:
    A deep color as the main fabric color, and a washed out color for grazing angle view (“side color”).
  4. An aiFacingRatio node is used as an input for incident angle info.
    * Note that in this case I checked the node’s invert option to make it behave more like other systems I’m used to (if you don’t use invert, the angle blend curve in 5 will be different..)
  5.  A remapValue node used to set the angle blend curve or in other words, how much does the color appears washed out per change of view angle of the cloth surface.
    * The longer it take the curve to become steep from left to right, the more the main color will be dominant before the washed out color will appear.
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  6. A colorCorrect node is used in this example just as a way to convert the remapped float value back to RGB for being multiplied with the cloth colors.
    * We could also connect it directly to the individual float components of the RGB colors but this way the node graph is cleaner.
  7. A multiplyDivide node is used to multiply the processed fabric texture with the 2 fabric colors “baking” the pattern into the color.
  8. A blendColors node is used to blend the 2 processed fabric colors together according to the processed facingRatio angle input.
    The result is the final cloth color that is connected to the aiStandardSurface shader.
  9. An aiBump2d node is used to convert the fabric pattern to normal data that will be connected to the aiStandardSurface shader to produce bumps.
  10. An aiStandartSurface shader serving as the main shading node for this material.
    * Note that under Geometry the Thin Walled option is checked so that the Subsurface layer of the shader will act as a Paper Shader rather than SSS.
    * The main cloth color is connected to the SubSurface Color input.
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Rendering an Animation in Maya and V-Ray

Software:
Maya 2018 | V-Ray 3.6

  1. Set a Project Folder or Image output path.
  2. In Render Settings > Common under Image File Output,
    Set a file name and format.
  3. In Render Settings > Common under Animation,
    Set Animation to Standard.
  4. Set the Maya UI to Rendering and choose Render > Render Sequence,
    Or simply press the Render Button in the toolbar.

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Related post:
Denoising animations with V-Ray for Maya

Maya V-Ray GPU texture resizing

Software:
Maya 2018 | V-Ray 3.6

By default V-Ray for Maya, when Production Engine is set to CUDA (GPU), resizes all the textures to 512×512 in order to save GPU memory.
Naturally, this may cause the textures to appear blurry and lacking detail in the rendered image.

To avoid this,
In Render Settings > V-Ray tab > Production renderer,
Set GPU Resize Textures to Full Size Textures, so the textures will not be resized at all (but consume more memory),
Or On-demand mipmapping, so the textures data will be optimized to reduce memory consumption (but not quality) in a pre-render process.

Note:
To get full size textures in IPR mode, do the same in the IPR tab

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Using VRayMtlHair3 shader with nHair in Maya

Software:
Maya 2018 | V-Ray 3.6

  1. Select the nHair object.
  2. In the Attribute Editor, in the hair system shape attributes.
    Open the Attributes menu, and choose VRay > Hair Shader.
  3. Create a VRayMtlHair3 shader.
  4. Connect the shader to the Hair Shader slot under VRay Extra Attributes in the hair system Shape Node attributes.

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Related:
V-Ray for Maya and XGen

Simple Toon shader setup in Maya & Arnold

Software:
Maya 2018

Use a Surface Luminance node as a V coordinate input value for a Ramp (V Ramp) node containing the toon colors.

* Note that the Clamp node is important so results will be ass expected, it clamps the Surface Luminance values to 0.99 so the V coordinate will nor cycle back to the beginning of the Ramp.

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Related:
Toon Shading in V-Ray for Maya

Arnold for Maya Motion-Blur

Software:
Maya 2018 | Arnold 5

  1. In the Render Settings window, Arnold Renderer tab, under Motion Blur,
    Check ‘Enable’.
  2. Set the ‘Length’ attribute to set the Motion-Blur size.
    * the default length of 0.5 means the Motion-Blur will be calculated as a result of a photographic exposure duration of half of a frame duration, or 180 degrees in cinema camera terminology.
  3. Raise the number of Keys to accurately simulate Motion-Blur for very fast rotational motion like helicopter propellers and car wheels.

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Note:
To generate a Motion Vector (Velocity) AOV (also referred to as ‘Render Element’ or ‘Pass’), in order to add the Motion-Blur effect in a compositing software:

  1. The ‘motionvector’ AOV must be added to the AOVs list in the AOVs tab of the Render Settings window.
  2. Motion-Blur must be enabled in the Motion-Blur part of the Arnold Renderer tab in the Render Settings window.
    * Otherwise motion vectors will not be calculated.
  3. In the Diagnostics tab of the Render Settings window, under Feature Overrides, check ‘Ignore Motion Blur’, so Motion-Blur will not be rendered.

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Related posts:

Arnold for Maya Depth of Field (DOF)

Saving multi-channel EXR file with Arnold for Maya