Normal mapping is a texture-based technique used to give the impression of sub-polygon lighting detail, without having to model it. It is controlled by a 'normal' texture, which is used to perturb the surface normal. Since only normals are perturbed, not geometry, it does not affect shadows.
The resolution of the normal map texture is important – you ideally want a one pixel per texel maximum resolution to get the best visual results. Magnifying the texture will blur the results and minifying will lessen the effect with distance.
The output of this shader is a perturbed normal.
General
Map
This is the texture map that contains the normals.
Unbiased Normals
8-bit integer texture maps normally store values between 0.0 and 1.0, but normals have component values between -1.0 and 1.0. When this is the case, the normals will have been pre-biased to fit into the 0.0 to 1.0 range. Check this option only when you know that the texture map is unbiased , meaning the normals were floating point and stored in the -1.0 to 1.0 range.
Flip Normal Y
This allows you to flip the y of the normal map, which is useful if the normal map was generated using a flipped uv coordinate system.
Scale Normal
This allows you to scale the resultant normal from the normal map, yielding a stronger 'bump' effect.
Advanced
Elliptical Filtering
Maximum Eccentricity
This specifies the maximum eccentricity for elliptical filtering. The higher the value the better the results, but at the cost of performance. A value of 1.0 is the same as bi-linear filtering.
Alternate
U / V
This specifies whether alternate texture coordinate repetition should be reversed.
Repeats
Texture Repeats
This controls the repetition of the texture coordinates. Normally a texture is mapped with values 0.0 to 1.0, to cover the whole texture. A 'Texture Repeat' value of 2.0, for example, means that the whole texture will fit twice in the same 0.0 to 1.0 range. Values lower than 1.0 effectively act as magnification.
Wrap U / V
This enables U/V wrapping when the values are out of the 0.0 – 1.0 range.
UV Remap
Minimum / Maximum
This specifies the range in which the texture coordinates will be remapped to.
Legacy Normal Map Technique
Introduced in Redshift version 3.5.11 Only relevant when normal mapping is used.
When disabled - by default, Redshift uses an enhanced normal map rendering technique. When enabled, Redshift will use the old normal map rendering technique which matches versions of Redshift rendered with 3.5.10 and earlier.
It is also recommended to set the Shading Normal Adaptation Technique to None instead of Keller to further match earlier versions of Redshift.
Legacy Normal Technique: Disabled Height Scale: 1
Enabled 1
Legacy Normal Technique: Disabled Height Scale: 5
Enabled 5
Normal Map Example
Here is an example of how a normal map can enhance the lighting detail of simple, flat geometry.
This example shows an un-textured surface, with a diffuse and glossy reflected spherical area light.
Now the same scene but with the normal map applied you can see how dramatically a normal map can increase the lighting detail without paying for the extra polygons.
The normal map that was used to create the effect.
