PBR is an acronym for Physically Based Rendering. It attempts to produce visuals in a way that mimics the flow of light in the real world by simulating how materials absorb and reflect light. Most recent game engines are increasingly using PBR textures due to their photorealistic effects. For real-time rendering, they are said to be the best approximation of real-world scenarios. To create an effect, most render engines have their unique workflows. However, PBR textures create the same effects in different software. As a result, in addition to photorealistic quality, exporting your project to another software becomes simple.
Several maps are utilised in PBR textures:
- Ambient Occlusion
The final product is made up of all of these maps. It is critical to understand what each of these maps accomplishes to achieve the best results. Once you’ve mastered the fundamentals, you can tweak the settings to achieve photorealistic results that mimic real-world conditions.
1. Albedo Map
Your entire material is built around albedo maps. Your pattern is either a single colour or a flat light image. The illumination must be flat. There should be no shadows displayed as the source photograph lighting may be different than yours. Shadows will generate irregularity in your textures and make them appear unnatural. Albedo mostly determines the colour of your texture. In metallic textures, it determines the colour of the material’s reflections.
2. Normal Map
The normal map provides your texture depth. It simulates the way light interacts with the surface of a substance using complicated computations to create smaller bumps and dents. Your basic geometry will not be altered by a normal map. As a result, after you pass a particular viewing angle, the effect may fade, especially on major rises or dips. A normal map’s base colour is a light purple; this is the bottom of the normal map, which symbolises your polygon mesh’s surface. Because normal maps determine how lighting interacts with your model, try to keep seams hidden. They can draw attention to seams.
3. Roughness Map
The roughness of a surface determines how rough or smooth it is. They determine how light is spread across your model’s surface. Rough surfaces scatter light in more directions than smooth surfaces, resulting in fuzzier rather than sharper reflections. The range of values is 0.0 to 1.0. When roughness equals 0.0, reflections are crisp, and your model does not scatter light at all, resulting in considerably sharper and brighter reflections and lighting on your material. Reflections get fuzzy when roughness equals 1.0. The light will be more dispersed throughout your material. Lighting and reflections are spread out more over the model, but they appear much dimmer as a result. e.g. Rubber has a roughness of about 1.0, whereas shiny plastic has a roughness of about zero. These maps are grayscale, with white representing the roughest surface and black representing a glossy, smooth surface.
4. Metalness Map
It refers to how much a surface reflects its surroundings. The range of values is 0.0 to 1.0. The albedo colour is entirely visible when metalness is 0.0, and the material seems to be plastic or ceramic. It appears to be painted metal when metalness is 0.5. When metalness reaches 1.0, the surface loses practically all of its albedo colour and just reflects the environment. When metalness is 1.0 and roughness is 0.0, for example, a surface resembles a real-world mirror.
Metal maps are likewise grayscale, but it’s preferable to stick to white and black values and utilise your roughness maps to fill in the gaps. The albedo map will be used as the diffuse colour (the colour the texture appears when it is touched with light) in parts of the metalness map that are black. Instead, White will determine the colour and brightness of your reflections using the albedo colour, and the diffuse colour of the material will be black. The diffuse colour is no longer required in this case because the reflections will provide all of the colour and detail for that section of the material, thus turning it black.
5. Specular Map
In PBR, specular maps can use full RGB colour, which has an impact on how you build your albedo. A specular map is sometimes used instead of a metalness map.
If you want to make a brass material out of a metal map, paint that portion of the map a brass hue in the albedo so that the reflections give the material a brass appearance. Instead, if you use a specular map, the brass area of your albedo will be completely black, and you’ll need to paint the brass detail onto the specular map to achieve the same effect. The benefit of this is that you can utilise the specular map to change how non-metallic materials manage reflections, giving you greater freedom and control. The disadvantage is that it can be difficult to exactly manage the outcome you want.
6. Height Map
Normal maps and height maps are similar in that they both provide minor details to your underlying mesh. The key distinction between the two is that, unlike a normal map, height maps actually add data to the 3D mesh and raise the poly count.
In the image above, you can see the mesh poking out where the ridges are on the sphere’s outside edge. When you look at the standard map, you’ll notice that the edge is still perfectly round, which breaks the sense of depth. Height maps are a type of grayscale map in which black represents the mesh’s bottom and white represents the mesh’s highest peaks, with shades of grey indicating everything in between. The benefit of height maps is the amount of detail they offer, which appears perfect from every angle and under any lighting condition. The necessity to tessellate the model, on the other hand, increases render times. As a result, normal maps are preferred for ease.
7. Opacity Map
You can use the opacity map to make areas of your material transparent. If you’re building glass or low-poly tree branches or decals, this is crucial.
It can be used in trees or decals, as shown in the image above. You can construct a complete bunch of leaves on a single polygonal plane and use an opacity map to make the excess of the polygon disappear. These polygons can then be layered to create realistic trees that require little processing power.
Grayscale opacity maps are available. White is completely opaque, while black is completely transparent. The varying levels of translucency between them are represented by the hues of grey. 0.0 is opaque, while 1.0 is transparent.
8. Ambient Occlusion
Ambient occlusion adds shadows to occluded portions of objects with crevices, making them appear more realistic. At render time, this map is mixed with the albedo to describe how it reacts to light. The map is grayscale, with white picking up the majority of the light and darker parts being more in shadow and less light reactive. The occlusion value ranges from 0.0 to 1.0, with 0.0 indicating complete darkness (occluded) and 1.0 indicating no occlusions.
9. Refraction Map
Refraction is the process of bending of light as it passes through a solid, liquid, or gas, distorting the way things seem when viewed through a transparent object, as defined by the name. It is the phenomenon that enables magnifying glasses to function and causes objects to seem differently when viewed underwater. It’s a crucial element of a material workflow because all transparent materials induce refraction in real life, thus it needs to be replicated in CG work to be as realistic as possible. In most cases, refraction maps are essentially a set of constant values. The sections of your model that you don’t want to refract light will almost certainly be opaque anyhow, so whether or not they refract light is unimportant.
10. Emissive Map
These maps cause some elements of your material to appear to radiate their own light, allowing them to be seen in dark places. Self-illumination is beneficial for illuminating small LEDs or creating unique strip lighting effects. However, if you apply too much, the detail in your scene will be completely washed out, and the scene will lose its liveliness. These are full RGB maps. They’re similar to an albedo map, but they’re for light. Although a self-illumination map can be used to illuminate a whole scene, it is much more complex than adding traditional lighting.