The goal of this post is to clarify the proper PBR workflow using the Default Shader in Terragen 4.5 and later. In this first example, we'll use a "Metalness - Roughness" workflow approach and assume that your 3D object has been UV mapped and that the texture maps were authored in a PBR software package such as Substance Painter.
As you can see in the imported object's internal node network view, each surface defined in the object has a single Default Shader assigned to the Shader input of the Object Part node.
Keep in mind that many of Terragen's parameters are meant to work together in order to achieve the final result. For example, the final surface colour is based on three parameters; the "Base colour", the "Colour image", and the "Colour function". Mathematically it looks like this:
Final colour = Base colour * Colour image * Colour functionColour TabThe base colour texture map should be assigned to the "Colour image" parameter, and the "Base colour" value should be set to 1. By default, the image projection is set to "Object UV (if available)" which can be found under the Images tab.
Roughness TabThe roughness texture maps should be assigned to the "Roughness image" parameter, and the Roughness value set to 1.
The "Remap ^2" checkbox provides additional compatibility with the way in which the roughness texture map was originally authored. Some 3D application shaders expect the roughness map to be linear, while others expect the map to contain square root values and the shader will raise them to the power of 2. If your material appears to be too bright, shiny or reflective, try disabling the "Remap ^2" checkbox.
Specular TabThe metalness texture map should be assigned to the "Metalness image" parameter, and the Metalness value set to 1.
Displacement TabThe height texture map should be assigned to the "Displacement image" parameter, and the "Displacement multiplier" value can be adjusted accordingly to increase or decrease the displacement. In this example, we converted the output from Substance Painter's normal texture map, to a height texture map via Bounding Box Software's Materialize application, as it gave us some additional control over the contrast in the texture image map.
The renders below illustrate the Metalness - Roughness workflow when authoring textures in a PBR application such as Substance Painter, and then assigning the texture maps to the Default Shader in Terragen.
