Introduction
There are many different texture maps these days when it comes to creating PBR (Physically-Based Rendering) materials. This can depend on the type of material being made, what software was used to create these maps, and how different 3D software label their texture maps. Knowing which map goes where can be confusing, but in this article we will guide you through what goes where.
We can divide the Corona Physical Material into two types: Metal and Non-Metal. Here's a breakdown of each:
Non-Metals
Albedo (Diffuse) Map – Base color input, which is the most important map, giving information about the color of the object. Unrealistically high albedo (such as RGB 255) leads to wrong "glowing white" object appearance and slows down the rendering.
IOR / Specular – Defines an object’s shininess by using a greyscale map. In its practical application the brighter the shade, the more light will be reflected. In the Corona Physical Material you can also choose between IOR and Specular workflow by going to the Advanced options rollout.
Roughness / Glossiness Map – This map controls the reflectivity of an object, whether the reflection of light will be blurred or sharp. In the Corona Physical Material you can also choose between Roughness and Glossiness workflow by going to the Advanced options rollout. A glossiness map is the inverse of a Roughness map.
Normal Map – This map makes the object surface appear uneven, for example it can feature dents and bumps. The normal map is saved in RGB format, containing its information in XYZ axes. Normal Maps should be always connected to a Corona Normal Map and then plugged into a material's Base Bump (or Clearcoat Bump).
Bump Map – Similar to the Normal Map, this map makes the object surface appear uneven. Bump maps are grayscale with white areas being interpreted as convex and black areas being interpreted as concave.
Alpha (Opacity) Map – This map controls the transparency of an object. Areas that are white in the map will be fully opaque, while black areas will be completely transparent. This map should be used in the Opacity slot.
Height (Displacement) Map – This map deforms the object surface. White areas result in convex deformation and black areas result in concave deformation.
Emission (Self-Illumination) Map – This map defines areas of a surface that will glow, but will not emit light the same was as the Corona Light Material does.
3ds Max - most common Non-Metal material set-up
Roughness mode is enabled by default. However, if you prefer to use a glossiness map, switch to Glossiness mode in the Advanced settings:
3ds Max - Roughness and Glossiness modes.
Note: a roughness map is the inverted version of a glossiness map. Glossiness maps highlight bright areas, while roughness maps highlight rough areas. Inverting one map gives you the other because they represent opposite surface properties.
Metals
Metalness Map – Saved as a grayscale this map controls the surface type. White translates into a pure metal surface, while black translates to non-metallic surfaces.
Albedo (Diffuse) Map – Base color input, which is the most important map, giving information about the color of the object. Unrealistically high albedo (such as RGB 255) leads to wrong "glowing white" object appearance and slows down the rendering.
IOR / Specular – It becomes active only when a metalness map is used. In that case, the IOR map defines the shininess of the non-metal areas by using a greyscale map. In its practical application the brighter the shade, the more light will be reflected. In the Corona Physical Material you can also choose between IOR and Specular workflow by going to the Advanced options rollout.
Roughness /Glossiness Map – This map controls the reflectivity of an object, whether the reflection of light will be blurred or sharp. In the Corona Physical Material you can also choose between Roughness and Glossiness workflow by going to the Advanced options rollout. A glossiness map is the inverse of a Roughness map.
Normal Map – This map makes the object surface appear uneven, for example it can feature dents and bumps. The normal map is saved in RGB format, containing its information in XYZ axes. Normal Maps should be always connected to a Corona Normal Map and then plugged into a material's Base Bump (or Clearcoat Bump).
Bump Map – Similar to the Normal Map, this map makes the object surface appear uneven. Bump maps are grayscale with white areas being interpreted as convex and black areas being interpreted as concave.
Alpha (Opacity) Map – This map controls the transparency of an object. Areas that are white in the map will be fully opaque, while black areas will be completely transparent. This map should be used in the Opacity slot.
Height (Displacement) Map – This map deforms the object surface. White areas result in convex deformation and black areas result in concave deformation.
Emission (Self-Illumination) Map – This map defines areas of a surface that will glow, but will not emit light the same was as the Corona Light Material does.
The image below depicts both workflows and where each shader map can be used:
3ds Max - most common Metalness material set-up
IOR mode is enabled by default. However, if you prefer to use Specular mode, you can switch to it in Advanced settings:
3ds Max - Switching between the IOR and Disney Specular modes.
In both of these workflows, it's important to note that you may not need all the maps in all situations, such as the normal map or the height map. At other times you may only need specific maps, such as the Ambient Occlusion map or the Emissive map. Each material has its own needs.
Chaos Cosmos
If you are looking for ready-made PBR materials, please keep in mind that there is the Chaos Cosmos Browser which comes included with the Corona installer for both Cinema 4D and 3ds Max.
Chaos Cosmos browser