In this tutorial, we will take you through the process of rendering a head model from nothing but a sphere and a vector displacement map. Vector displacement maps are a powerful and efficient way to add detail to your scene without the overhead of managing complex geometry. They provide a very efficient workflow when working with models from 3D sculpting applications and Arnold. Unlike traditional gray scale displacement maps which simply use a line long for the vertex normal, vector displacement maps have RGB values which represent the XYZ displacement direction and size. This means they don't follow a fixed surface normal and can move in any direction, including overlapping each other.
However, vector displacement maps have larger file sizes because they have to store more information than regular displacement maps. Also bear in mind that vector displacement maps, as with normal displacement maps, are not perfect for every situation. For example, UV seams can be problematic when using vector displacement maps.
Many thanks to the very talented Zeno Pelgrims for providing the assets and assistance for this tutorial.