Normal Map - Digital Art Garden

# Normal Map [[Normal Map|Normal Maps]] are texture images that create the illusion of depth, without affecting the geometry of the model, contrary to a [[Displacement Map]]. ![[normal-map-ambience.webp]] Brick Material Normal Map (source: ==AmbientCG==). ![[normal-map.webp]] Brick Material Normal Map (source: ==AmbientCG==). Normal Maps use RGB values to store the surfaces normals information, ==creating an illusion of depth==. The RGB values represent the X, Y and Z coordinates of the surface normals. A Normal Map's base color (where all normals are perpendicular to the face) is ==0.5, 0.5, 1==. This color was not chosen arbitrarily. As RGB colors only go from 0 to 1, the normal values are remapped so that -1 becomes 0, 0 becomes 0.5 and 1 becomes 1. Thus a color value of 0.5 translates to a normal of 0. ![[normal-base-color.webp]] A "blank" Normal Map would thus be read as having a z value of 1, with the x and y values being 0. These normal values (0(X), 0(Y), 1(Z)) translate to a color value of 0.5, 0.5, 1 (or ==128, 128, 255==). This is also the reason why Normal Maps appear blue-ish. ## Tangent vs. Object vs. World Space Normal Maps The orientation of the coordinate axes depends on the space used: ### Tangent Space Normal Maps ### Object Space Normal Maps ### World Space Normal Maps ## Normal Map GL vs DX When downloading PBR texture sets from online resources such as [AmbientCG](https://ambientcg.com), you will notice that there are often two types of Normal Maps, for example: - ScrewSet001_4K-JPG_Normal==GL==.png - ScrewSet001_4K-JPG_Normal==DX==.png To understand the difference, it is important to note that there are actually two standard formats for Normal Maps: ==OpenGL (GL)== and ==DirectX (DX)==. These two standards are also known as left-handed or right-handed Normal Maps. Both are equally compatible, the only difference is that their green channel (the Y coordinate) is inverted/flipped. In terms of the "handedness" this means left-handed correlates to -Y and right-handed to +Y. ![[normal-map-gl-dx.webp]] Normal Map GL (left) and DX (right) comparison. As of when to use what type of format, it depends on the software being used: - [[Blender]] for example ==uses OpenGL==, which means you would use the NormalGL.png Normal Map. - [[Unreal Engine]] on the other hand ==uses DirectX== by default. > [!NOTE] > You can of course also use a DirectX Normal Map inside **Blender** by simply inverting the green channel using Nodes. ## Normal Map vs Bump Map While Normal Maps can be seen as a type of [[Bump Map|Bump Maps]] and are both used for creating the illusion of depth to a model, they still differ in functionality: - Normal Maps use RGB Values - Bump Maps are greyscale images ## Normal Map vs Displacement Map Normal Maps (and Bump Maps) create a fake impression of depth, whereas a [[Displacement Map]] actually modifies the topology and its quality is also dependant on the quality (polycount) of the mesh. You can read more on Displacement Maps [[Displacement Map|here]]. ## How to Create Normal Maps You can create Normal Maps yourself off of photographs using Normal Mappers such as [NormalMap Online](https://cpetry.github.io/NormalMap-Online/) or [GIMP](https://www.gimp.org). As a base use a greyscale image (height map) of your desired image texture. If your base is not an image but a 3D model you can bake the Normal Map in the used 3D software.