PBR (Physically Based Rendering) is a shading paradigm that has become increasingly popular in the gaming industry recently. It uses cutting-edge lighting calculations. It attempts to generate more realistic lighting environments by correctly modeling how light interacts with surfaces using lighting physics and real material values. We now have dynamic lights that create realistic shadows, as well as image-based lighting that provides correct diffuse and specular reflections in the surrounding environment.
PBR materials now have two process options: specular (PBR-Specular) and metallic (PBR-Metalliccular). The purpose of this is to allow our users to import these textures into a variety of accessible 3D applications. PBR-Metallicular is a simplified version of PBR-Specular. It's ideal for beginner artists or those who have problems converting from specular mapping to the PBR method.
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1. PBR-Specular workflow
PBR -Specular uses diffuse, specular and glossiness maps.
Diffuse maps contain only diffuse color, no shadow or lighting data. When using stylized and/or hand-painted textures, shaders and ambient occlusion are often baked into the diffuse map. Shaders are handled by the system and ambient occlusion is handled by a separate map in the PBR. On this map, the metals should look black because they have no diffuse color.
The specular map contains the color of the specular reflection. Non-metals should be grayscale and dull, while metals should be bright and colorful.
The appearance of specular reflections is controlled by Glossiness. As mentioned earlier, the strength and size of specular reflections are determined by the roughness or glossiness of the surface. Whiter values indicate smoother or smoother surfaces on this grayscale map.
2. PBR-metalliccular workflow
PBR metal uses base color, metallicity, and roughness maps.
The base color map contains metallic specular reflection colors and non-metallic diffuse reflection colors. Basically, the diffuse and specular maps from the specular workflow will be merged into this map.
The Metallic map is a grayscale map that tells the shader whether the colored part is made of metal. Metals are represented by black, while non-metals are represented by white.
The roughness map is the opposite of the glossiness map, with whiter values indicating a rougher surface.
The Metallicity workflow removes control over non-metallic F(0) values, which can often be used incorrectly, thus making them preferable to specular. It also saves memory because two-thirds of the map is grayscale, compared to only one-third in the specular pass.
3. Universal stickers
In addition to the maps mentioned above, there are a variety of other common maps that can be used and are often needed to produce the desired aesthetic, regardless of the workflow. Some of them are:
- Normal: Normal map: Roughness/glossiness map should reflect this added detail
- Height: height map
- Bump: Bump map
- Ambient Occlusion: Ambient Occlusion
- Opacity: Opacity
- Emissive: self-illumination
4、PBR-Metalliccular vs. PBR-Specular
Both workflows provide excellent results, but each has its own advantages and disadvantages.
The PBR-Specular workflow uses a specular color map in conjunction with a gloss map to get correct specular reflections. This has both strong benefits and significant drawbacks, especially when it comes to game creation.
The PBR-Metalliccular workflow is inherently memory-friendly and therefore generally more suitable for game development.
| PBR-Specular Workflow Benefits | PBR-Specular Workflow Disadvantages |
|---|---|
| The RGB color map contains all specular features. This map has a very good result because it uses data from all three color channels. | You lose the option to pack black and white maps into RGB channels, as full color maps are used for greater accuracy. |
| Diffuse and reflectance are controlled directly via two clear inputs, which artists with shader knowledge may prefer. | Illogical reflectance values are easy to use and produce erroneous results. |
| Complete color input gives you greater control over insulator reflectivity. | It uses more texture memory compared to the metallicity workflow. |
| PBR-Metalliccular workflow advantages | PBR-Metalliccular Workflow Disadvantages |
|---|---|
| Metal can be used in the color channel of the Packed Map because it is black and white. These maps contain a different grayscale texture for each possible color channel (red, green, blue). MRA maps (Metal, Roughness, Ambient Occlusion) or similar are common ways to save memory when using PBR-Metal. | Artifacts may occur because the metallic map provides less information than the specular color map and is used as a mask in the shader. It's usually minor, but can sometimes be a major issue, especially in games with complex surfaces directly from the player's camera. |
| Albedo maps define the color of an item regardless of the type of substance, theoretically making it easier for artists to master. | White line artifacts are caused by material transition points. |
| Materials are simplified into two categories, insulators and metals, which can make it more difficult to create content with unrealistic texture values. | It provides less control over insulator reflectivity |
| It uses less texture memory than full-color specular technology. | If an artist doesn't master the workflow, they can use incorrect values in the metallicity map and break the system. |
Original link: PBR Texture: Metallic vs. High Gloss — BimAnt