Normal and Bump Maps both serve the same purpose: they simulate the impression of a detailed 3D surface by modifying the shading as if the surface had many small angles instead of being completely flat. The Maps are important when creating a 3D configurator. Because it’s just a change to the shading of each individual pixel, it doesn’t cast shadows and doesn’t interfere with other objects. If the camera angle is too flat to the surface, you will notice that the surface is not really shaped.
Both bump and normal maps work by changing the normal angle (the direction perpendicular to a surface), which affects the shading of a pixel. Although the terms normal and bump map are often used synonymously, there are certain differences.
These are textures that store an intensity, the relative height of pixels from the camera’s point of view. The pixels seem to be shifted by the required distance towards the area normal. (The “dent” consists only of a displacement that takes place along the existing and unchanged normal vector of the surface). You can use either grayscale images or the intensity values of an RGB texture (including images).
These are images that store the direction of the normal directly in the RGB values of an image. They are much more accurate because they not only simulate that the pixel is along a line away from the face, but can also simulate that the pixel is moved in any direction and in any way. The disadvantages of normal maps are that unlike bump maps, which can easily be painted by hand, normal maps usually have to be generated in some way, often from geometries with higher resolution than the geometry to which you apply the map.
Normal Maps in Blender store a normal value as follows:
- Red Maps from (0 – 255) to X (-1.0 – 1.0)
- Green Maps from (0 – 255) to Y (-1.0 – 1.0)
- Blue maps from (0 – 255) to Z (0.0 – 1.0)
Since Normals all point to one viewer, negative Z values are not saved (they would be invisible anyway). In Blender we store a full blue area, although some other implementations also map blue colors (128 – 255) to (0.0 – 1.0). Last convention is used e.g. in “Doom 3”.
The steps that are performed when creating and using Bump & Normal Maps are:
- Model a highly detailed (“Hi-Poly”) model.
- Beacon the bump and/or normal map.
- Create a low-poly, less detailed model.
- Assign the map to the low-poly model with a common coordinate system.
The beacon of a model, simply put, is to take the detail of a high polygon mesh and apply it to a similar object. The similar object is identical to the high poly mesh, with the exception of fewer nodes. Use the Render Beacon in Blender function to do this.
Modeling a low-poly with Blender’s mesh editing tools. In general, the same or similar surfaces should be present that reflect the model. For example, a highly detailed ear in the High Poly model may have 1000 faces. In the low-poly model, this can be replaced by a single plane oriented in the same direction as the detailed ear mesh. (Tip: Blender’s multi-resolution mesh modeling function can be used very well here).
Mapping is the process of applying a texture to the Loy-Poly-Mesh. Further information on applying a texture to the material of a mesh can be found in our article on Texture Mapping. Special considerations for Bump and Normal Maps are:
- If you are using a bump map, map the texture to normal and do not activate RGB.
- If you are using a normal map, map the texture to the normal.
The coordinate systems of the two objects must match. For example, if you beacon a UV map of the high poly model, you must create the low poly model UV maps and align the UV coordinates to match the contour of the high poly image.
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