OBJ color and MTL material settings

Nira fully supports OBJ files exported from RealityCapture or Zbrush that contain vertex color information. Vertex colors from Zbrush are often referred to as "polypaint".

OBJ files will typically have a corresponding MTL file that defines the material parameters.

Example settings of the various MTL settings that Nira supports is listed below:

• Red Color:
  • Kd 1.000 0.000 0.000
• Color texture:
  • map_Kd BaseColor.png
• Green Specular Color
  • Ks 0.000 1.000 0.000
• Specular texture:
  • map_Ks specular.png
• Roughness parameter:
  • Pr 1.000
• Roughness texture (should be greyscale)
  • map_Pr roughness.png
• Glossiness parameter:
  • Ns 1.000
• Glossiness texture (should be greyscale)
  • map_Ns gloss.png (inverted roughness signal)
• Metalness parameter:
  • Pm 1.000
• Metalness texture (should be greyscale)
  • map_Pm metallic.png
  • refl metallic.png
• Ambient Occlusion texture (should be greyscale)
  • map_Po ambientOcclusion.png
• Blue Emissive Color:
  • Ke 0.000 0.000 1.000
• Emissive texture:
  • map_Ke emissive.png
• Normal texture:
  • map_bump normal.png
• Opacity
  • d 1.000
• Opacity Texture:
  • map_d opacity.png
• Transparency
  • Tr 1.000
    • Note: inverted for models exported from Meshlab: # Converted by Meshlab Group

Use the -imfchan flag before the file name when using packed textures -- multiple signals saved into a single texture file. These are sometimes referred to as ORM textures -- Ambient Occlusion in the red channel, Roughness in the blue channel, and Metallic in the green channel.

• map_Po -imfchan r car_ORM.tga
• map_Pr -imfchan b car_ORM.tga
• map_Pm -imfchan g car_ORM.tga