How to solve the problem of normal mapping?
The normal map is defined in tangent space, so one way to solve the problem is to calculate a matrix to transform normals from tangent space to a different space such that they’re aligned with the surface’s normal direction: the normal vectors are then all pointing roughly in the positive y direction.
Can a normal map be reused on multiple models?
However object-space normal maps cannot be easily reused on multiple models, as the orientation of the surfaces differ. Since color texture maps can be reused freely, and normal maps tend to correspond with a particular texture map, it is desirable for artists that normal maps have the same property.
How does displacement mapping differ from normal mapping?
Because they only change the normal, they do not affect the silhouette of the object. For example, if you add normal mapping to a sphere, you can make the surface area of the sphere look rough and craggy, but the edges will still be perfectly smooth. Displacement maps add actual new geometry at render time.
How does normal mapping affect the silhouette of an object?
Normal maps store vectors as RGB in a color map. Because they only change the normal, they do not affect the silhouette of the object. For example, if you add normal mapping to a sphere, you can make the surface area of the sphere look rough and craggy, but the edges will still be perfectly smooth.
How are normal vectors expressed in a normal map?
Normal vectors in a normal map are expressed in tangent space where normals always point roughly in the positive z direction. Tangent space is a space that’s local to the surface of a triangle: the normals are relative to the local reference frame of the individual triangles.
How is tangent space related to normal mapping?
Tangent space is a space that’s local to the surface of a triangle: the normals are relative to the local reference frame of the individual triangles. Think of it as the local space of the normal map’s vectors; they’re all defined pointing in the positive z direction regardless of the final transformed direction.