V-Ray Next’s PBR’ness

Software:
3ds max 2019 | V-Ray Next

A quick test of V-Ray Next‘s PBR workflow,
Namely designing materials while previewing them using V-Ray,
Defining the material properties using the new (to V-Ray) Metalness attribute, and using Roughness rather than Glossiness, shows good results IMO.

Results are generally consistent through Blender & Cycles, Maya & Arnold, and UE4.

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Related Posts:

  1. V-Ray Next – Metalness
  2. Metal In UE4
  3. Fresnel Reflections
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IES Lighting in CG

IES stands for Illuminating Engineering Society, it is the organization responsible for creating and maintaining industrial standards for design and manufacturing of artificial light sources.

In 3D rendering, an IES file or “photo-metric file” is a text file containing a physical description of a light source’s beam spread , pattern and intensity, allowing for faithful depiction of the light source in 3D renders.
Most modern 3D rendering software support IES lights, that is allow loading IES files into the software and lighting the 3D scene using the light source described in the IES file.

Lighting manufacturers make measurements of their light fixture model’s physical light output and create IES files available for download on their websites.
This allows architects, lighting designers, and interior designers to download the files and realistically visualize the light sources effect on their projects.

CG artists use IES lights to add realistic spotlight beam patterns to their renderings and animations, such that can’t be created using regular simple 3D light sources.

Examples of IES lights rendered with V-Ray for 3ds max:

IES

Related:
IES Spotlights for Blender & Cycles

V-Ray for Maya toon shading

Software:
Maya 2018 | V-Ray 3.6

Toon shading in V-Ray consists of two elements:

  1. A VRayToon node that creates a graphic contour effect on the rendered image.
  2. A flat shader that uses surface luminance data to define color areas.
    * A VRayLightMtl can be used for that.

Creating the VRayToon node:

  1. Click the Create V-Ray Toon button in the V-Ray toolbar to create a VRayToon node.
  2. In the VRayToon node attributes, set line thickness, color, and more graphic properties.
    * if you created a VRayToon node and it’s not selected RMB click the Create V-Ray Toon button in the V-Ray toolbar and choose Select VRayToon node.
    * To delete the VRayToon node, select it and press Delete.

Creating the toon shader:

  1. Create a VRayLightMTL node as the object’s surface shader.
  2. Create a Ramp texture node, connect it’s output color to the VRayLightMTL’s color input and delete it’s accompanying 2D placement node.
  3. Create a surfaceLuminance node and connect it’s output to the Ramp node’s V Coord input.
  4. Optional remapValue node between the surfaceLuminance node and the Ramp node to clamp the luminance values.
  5. Optional floatMath node to scale or manipulate the surfaceLuminance output value.

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Related:
Arnold for Maya Toon Shading

VRayMtl’s new metallic goodness

Software:
3ds max 2019 | V-Ray Next | V-Ray next GPU

In V-Ray Next (4) for 3ds max, a new Metalness parameter has been added to the Reflect parameters of the VRayMtl material.
This allows for easy creation of realistic metal materials and also effectively enables a PBR workflow with V-Ray.

When the Metalness parameter is set to 1.0, the material becomes completely reflective, the Diffuse color controls the general reflection color, and the Reflect color (which should generally be set to white) controls the reflection color at grazing incidence angle.

The IOR parameter still controls how fast will the main reflection color (set by the Diffuse color) blend into the Reflection color, and I don’t know whether some form of complex Fresnel has been implemented or if it’s just a dielectric simple Fresnel blended over a reflective surface.

An excellent article on the new Feature from the Chaos Group blog:
https://www.chaosgroup.com/blog/understanding-metalness

VRay_Next_Metalness

Related:

  1. Fresnel Reflections
  2. Complex Fresnel for Blender & Cycles
  3. Metal material in UE4

 

Arnold for Maya refractive caustics

Software:
Maya 2018 | Arnold 5

An account of the drastic measures that need to be taken in order to ‘persuade’ Arnold for Maya to render refractive caustics.

  1. In the refractive object’s shape attributes,
    Under ‘Arnold’, ‘Opaque’ must remain checked.
    * This is unintuitive but when refractive caustics are calculated there is no need for transparent shadows. the caustics pattern is in fact the light refracting through the object.
  2. The refractive object’s aiStandardSurface shader must have it’s Transmission layer active.
    For a colored refractive object, Transmission Weight should be 1.0,
    A color should be selected, and the density of the color should be controlled with the Depth attribute (higher values make the color less dens).
    In the shader’s advance attributes, check ‘Caustics’.
    In the shader’s Specular layer, set the IOR to match your material.
    * The default of 1.52 is the IOR for glass, and water would be IOR 1.33 for example.
  3. For refractive caustics to be rendered, the light source must be an Arnold Mesh Light,
    And in its shape attributes, under Light Attributes ‘Light Visible’ must be checked.
  4. In many cases, in order for the caustics pattern’s intensity to be correct,
    The ‘Indirect Clamp Value’ must be raised in Render Settings > Arnold Renderer, under Clamping.
  5. In some cases the Transmission value under Ray Depth in Render Settings > Arnold Renderer must be increased for the caustics to render properly.
    * Light simulation must be able refract through all the relevant surfaces.
  6. To increase the caustics render quality, the number of Diffuse samples must be raised in Render Settings > Arnold Renderer.
    * This may be unintuitive, but the caustics pattern is actually part of the Diffuse rendering of the surface upon which the caustics are appearing.

That’s it!
Hope you find this useful 🙂

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Saving multi-channel EXR with Arnold for maya

Software:
Maya 2018 | Arnold 5

  1. In the Render Settings > Common tab, choose EXR as the output file format.
  2. In the Render Settings > AOVs tab, open the drop-down menu on the right side of one of the AOVs in the list, and choose Select Driver.
    This will bring up the defaultArnoldDriver node Attributes.
  3. In the defaultArnoldDriver node Attributes, under Advanced Output, check Merge AOVs.

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