PBR is an acronym for Physically Based Rendering. It attempts to produce visual effects in a way that mimics the flow of light in the real world by simulating how materials absorb and reflect light. Recent game engines are increasingly using PBR textures for their realistic effects. For real-time rendering, they are considered the best approximation of real-world scenes.
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In order to create effects, most rendering engines have their own unique workflow. However, PBR textures create the same effect in different software. So, in addition to the photorealistic quality, exporting your project to another software becomes simple.
Several maps are used in PBR textures:
- Albedo: Albedo
- Normal: Normal
- Roughness: roughness
- Metalness: Metalness
- Specular: mirror surface
- Height: height
- Opacity: Opacity
- Ambient Occlusion: Ambient Occlusion
- Refraction: Refraction
- Emissive: self-illumination
The final product consists of all these maps. It's crucial to understand what each of these maps accomplishes to get the best results. Once you've mastered the basics, you can tweak settings for photorealistic results that mimic real-world conditions.
1. Albedo map
Your entire material is built around the albedo map. Your pattern is a single color or flat light image. Lighting must be flat. Shadows should not show because the source photo lighting may be different from yours. Shadows can create irregularities in textures and make them look unnatural. Albedo primarily determines the color of the texture. In metal textures, it determines the color reflected by the material.
2. Normal map
Normal maps provide texture depth. It uses complex calculations to simulate the way light interacts with material surfaces to create smaller bumps and indentations. Normal maps don't change your base geometry. Therefore, after passing through a certain perspective, the effect may be weakened, especially on a large rise or fall.
The base color of the normal map is light purple; this is the bottom of the normal map and is used to symbolize the surface of the polygon mesh. Since the normal map determines how the light interacts with the model, try to hide the seams as much as possible. They can draw attention to the seams.
3. Roughness map
The roughness of a surface determines how rough or smooth it is. They determine how light is distributed on the surface of the model. Rough surfaces scatter light in more directions than smooth surfaces, resulting in blurrier rather than sharper reflections.
Values range from 0.0 to 1.0. When roughness equals 0.0, reflections are clear and the model does not scatter light at all, resulting in cleaner, brighter reflections and lighting on the material. When roughness equals 1.0, reflections become blurred. The light will be more dispersed throughout the material. Lighting and reflections are distributed more over the model, but they appear much darker as a result. For example, rubber has a roughness of about 1.0, while shiny plastic has a roughness of about zero. The maps are grayscale, with white representing the roughest surfaces and black representing smooth surfaces.
4. Metallic map
It refers to the degree to which a surface reflects its surroundings. Values range from 0.0 to 1.0. When metallicity is 0.0, the albedo color is fully visible and the material appears to be plastic or ceramic. When the metallicity is 0.5, it appears to be painted metallic. When metallicity reaches 1.0, the surface loses almost all albedo color and only reflects the environment. For example, with a metalness of 1.0 and a roughness of 0.0, the surface resembles a real-world mirror.
The metal map is also grayscale, but it's best to stick to white and black values and use the roughness map to fill in the gaps. The albedo map will be used as the diffuse color for the black parts of the metallic map (the color the texture appears when light hits it). Instead, white will use the albedo color to determine the color and brightness of reflections, and the material's diffuse color will be black. In this case the diffuse color is no longer needed as the reflection will give all the color and detail to that part of the material, turning it black.
5. Mirror map
In PBR, specular maps can use full RGB colors, which affects how you build albedo. Specular maps are sometimes used instead of metallic maps.
If you are making a brass material with a metal map, paint that part of the map a brassy tone in the albedo so that the reflections give the material a brassy appearance. In contrast, if you use a specular map, the brass areas of the albedo will be completely black and you will need to paint the brass details onto the specular map to achieve the same effect. The advantage of this is that you can take advantage of specular maps to change how non-metallic materials manage reflections, giving you more freedom and control. The downside is that it can be difficult to manage exactly the results you want.
6. Height map
Normal maps and height maps are similar in that they both provide secondary detail to the underlying mesh. The main difference between the two is that, unlike a normal map, a height map actually adds data to the 3D mesh and increases the polygon count.
In the picture above, you can see the mesh sticking out at the ridges on the outer edge of the sphere. When you look at the standard map, you'll notice that the edges are still perfectly round, which breaks the perception of depth. A height map is a grayscale map where black represents the base of the grid, white represents the highest peaks of the grid, and shades of gray represent everything in between. The benefit of height maps is the amount of detail they provide, which looks perfect from all angles and in any lighting condition. On the other hand, the necessity to subdivide the model increases rendering time. Therefore, normal maps are preferred for convenience.
7. Opacity map
Areas of a material can be made transparent using an opacity map. This is crucial if you are building glass or low poly branches or decals.
It can be used for trees or decals as shown above. You can construct a whole bunch of leaves on a single polygonal plane and use an opacity map to make the excess of polygons disappear. These polygons can then be layered to create realistic trees that require very little processing power.
Grayscale opacity map available. White is completely opaque, while black is completely transparent. The varying degrees of translucency between them are indicated by shades of gray. 0.0 is opaque, while 1.0 is transparent.
8. Ambient light occlusion map
Ambient Occlusion adds shadows to occluded parts of objects with gaps, making them appear more realistic. When rendering, this map is mixed with the albedo to describe how it reacts to light. The map is grayscale, with white taking up most of the light, while the darker parts are in shadow with less light reaction. Occlusion values range from 0.0 to 1.0, where 0.0 is complete darkness (occlusion) and 1.0 is no occlusion.
9. Refraction map
Refraction is the process by which light bends as it travels through a solid, liquid, or gas, distorting its appearance when viewed through a transparent object (as the name implies). It's this phenomenon that makes a magnifying glass work and causes objects to look different when viewed underwater. This is a key element of the material workflow as all transparent materials cause refraction in real life, so this needs to be replicated in CG work to be as realistic as possible. In most cases, a refraction map is essentially a set of constant values. In any case, the parts of the model that you don't want to refract light are almost certainly opaque, so it doesn't matter whether they refract light or not.
10. Self-illuminating map
These maps make certain elements of the material appear to emit their own light, making them visible in dark places. Self-illumination is good for illuminating small LEDs or creating unique strip lighting effects. However, if too much is applied, the details in the scene will be completely washed out and the scene will lose its vitality. These are full RGB maps. They are similar to albedo maps, but they are used for light. While emissive maps can be used to light an entire scene, it's more complicated than adding traditional lighting.
Original link: 10 types of maps for PBR textures—BimAnt