What are Normal Maps?
A normal map is an image that stores a direction in each pixel- these directions are known as normals.
The RGB channels are used to control the direction of each pixel’s normal.
A normal map is commonly used to fake high-resolution details on a low-resolution model. Each pixel of the map stores the surface slope of the original high-res mesh at that point. This creates the illusion of more surface detail or better curvature. However, the silhouette of the model doesn’t change.
Normal Maps explained. (YouTube, 2017).
Normal maps are similar to bump maps in that they effect the normals, creating the illusion of detail without having to rely on a high poly count.The main difference between bump maps and normal maps is that bump maps only records height information, whereas normal maps used RGB values to show the orientation of the surface normals. These values in the RGB channels correspond to the XYZ locations on a graph.
Used today to bake high poly details onto low poly maps, giving high resolution details.
There are two types of normal maps, tangent space and object space.
Tangent space are blueish purple and can be used on objects that need to deform, such as an animated character.
An older tangent spaced normal map from our dinosaur model.
Object space normal maps are more of a rainbow colour, and have slightly improved performance compared to the tangent based maps. Object space are used on objects that need to move and rotate, but not necessarily deform.
Object spaced normal map on a tyre. (Community.foundry.com, 2017).
Using Normal maps in Arnold
-When using Color Management in Maya (2017), normal maps should be set to RAW
– In 2D attributes, the colour space must be set to tangent spaced normals
– flipping certain channels may be necessary. FlipR- flips the red channel, FlipG flips the green channel and Swap tangents swaps the Red and Green channels on the normal map.
YouTube. (2017). CG101: What is a Normal Map?. [online] Available at: https://www.youtube.com/watch?v=yHzIx41eiD4 [Accessed 21 Mar. 2017].
Community.foundry.com. (2017). Index. [online] Available at: http://community.foundry.com/discuss/topic/43591 [Accessed 21 Mar. 2017].