Textures

There are four textures utilized by the Digital_Human Hair shader, they are Hair Tangent Map, Hair Specular Mask Map, Hair Root Map and Hair ID Map.

By default, when you convert the shader of the hair from PBR to Digital_Human Hair shader, the Base Color texture will be auto-loaded into the Hair Specular Mask Map in Grayscale; and the Hair Tangent Map is empty. You need to manually create one for this channel because the UV settings of a hair content will vary upon creation.

• Hair Tangent Map and Hair Flow Map: These two channels are exclusive to each other. If one is loaded with a texture, the other will be disabled. The texture in the Hair Tangent Map channel must be created via specific procedure; while the texture in the Hair Flow Map channel can be easily created for defining the hair direction with Red and Green colors. This texture ensures the correctness of the highlights on the hair.
  1. Apply a hair to the character and convert it into Digital_Human Hair shader. Notice the faulty metallic reflections:
     
  2. Open the Base Color texture in your image editor.
  3. Check out the hair flow in the texture.
     
  4. Create another image and apply red for the vertical direction and green for the horizontal direction.
     
  5. Save this image and load it into the Hair Tangent Map channel.
  6. The reflections now appear correctly.
     
• Hair Specular Mask map: This texture is used to define the specular reflection one the hair in grayscale.
  
  This texture is desaturated from the Base Color texture in order to restrain the over-exposed reflections on the hair caused by the roughness and metallic textures.
  

  Hair with Hair Specular Mask map	Hair without Hair Specular Mask map

• Hair Root map: This texture is used to define the roots and ends of the hair. The black areas define the roots while the white ones defines the ends. With this map, it is possible to blend different colors to the roots or ends of the hair.
  
  

  Hair without Hair Root map	Hair with Hair Root map

• Hair ID map: This texture is used to define the hairs on each piece of the mesh with black, white and gray. With this map, you can blend different highlight colors to the hair.
  
  

  Hair without Hair ID map	Hair with Hair ID map