Texture map is an image applied to the surface of a shape or polygon 2. They can consist of one to three dimensions and can also be two dimensional (most commonly used for visible surfaces).Texture mapping is a method for defining surface texture and color information on a 3D model or computer-generated graphic. Texture mapping originally was a method which now is called diffuse mapping that simply wrapped and mapped pixels from a texture map to a 3D surface. In recent years the technology made it possible to simulate near photorealism in real time by reducing the number of polygons and the light calculations needed to construct a realistic looking 3D scene. This is possible by used materials which contain different complex maps in them. For example materials have specular and reflection mapping, normal and bump mapping, occlusion mapping and many more.Before PBR texturing workflow was created artists had to use a traditional texturing workflow. This means that texture artists had to manually tweak the lightness of the diffuse map in order to make an asset look good under different lighting set ups. Maps such as ambient occlusion and Cavity details were baked directly on top of the diffuse map. Specular map was also used to represent both reflectivity and microsurfaces.  Physically Based Rendering is a method of shading and rendering that provides more accurate representation of how light interacts with surfaces 6.Diffuse and reflection is two different terms used to describe how light rays will interact with materials when it hits the surface 3. Every material has its own reflectivity and will absorb or reflect light differently. For example, a smooth metal material will have more of a mirror-like appearance and reflecting more light than a rubber material will.This means that reflection and diffusion are mutually exclusive.Energy conservation means that the light witch is leaving the surface of an object will never be brighter than the light that hit the surface first. This means that if more light rays penetrate the surface of a material the less of them will bounce back. On the other hand, highly reflective objects will show almost no diffuse light, because the light that penetrates the surface is too little.Fresnel effect is named after the French physicist Augustin-Jean Fresnel who lived in the 19th century. In the computer graphics world the word Fresnel describes the differing reflectivity that occurs at different angles 5. For example, light that lands on a surface at a grazing angle will be much more likely to reflect than that which hits the surface straight on. This means that an object which is rendered with Fresnel effect will have brighter reflections near the edges rather than near the center.  There are two types of materials in the real world. Conductors (metals) and Insulators (dielectric). Metals absorb most of the light that enters the surface. Most of the visible light is reflected and because of that its diffuse color is usually close to black. Metals usually have higher specular reflection than diffuse reflection.On the other hand dielectric materials have larger diffuse reflection and lower specular reflection. Such materials are water, wood, plastic and stone.Microsurface details are an important characteristic for any material. In real life materials have imperfections such as cracks or bumps which impacts how light behaves when it reaches the surface. These small details are usually barely seen by a naked eye but they can have big impact over the diffusion and reflection of a material. Since it is impossible to represent all these details on a normal map there are written shaders which can reproduce similar results. The theory states that the more rough the surface is the more reflected light will appear blurry.Some materials have more complex diffusion that can not only be determined by a single attribute. For example, translucency is when the light could pass through the object and come out of the other side intact. Such materials with translucency are skin and wax. This effect can be seen clearer if the object is thin and light can pass through easier. The shading system then has to take into account both thickness and shape of the object in order to render accurate translucency.Transparency on the other hand can be found in materials such as water and glass. If the diffusion is even lower then almost no scattering is visible and the entire images can pass through an object from one side to the other.When creating textures artists have to be mindful of the limitations that some of the platforms present in front of them. For example creating a game for mobile device can have many limitations on the hardware. Texture sizes would be smaller like 512×512 or 1024×1024 while on the other hand pc’s and console would have less limitation with texture sizes like 2048×2048 and 4096×4096. Textures are usually exported as a .tga, .png and .jpeg. File formats such as jpeg and png are smaller sizes but they don’t contain an alpha channel while on the other hand tga have an alpha channel included but creates a bigger size image.The two most common PBR workflows are Metalness/Roughness and Specular/Glossiness workflow. The main difference between the two is how the diffuse and reflectivity information is defined in the texture maps. A difference between the two workflow is that sometimes in metalness workflow on the edge of some materials such as metal and wood there might appear some artifacts which in specular workflow happens rarely.Diffuse and Albedo maps are used to define the objects color. In metalness map workflow the diffuse map is used to define the colors of all materials but in specular workflow metal materials will appear black and other insulators have their own color.


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