Arnold VOP networks (and ROPs) can be upgraded to the current version of Arnold and HtoA. You can globally convert all the deprecated shaders in the scene from the Arnold menu (Arnold-> Upgrade Deprecated Shaders or right click shader Convert to...). The conversion will attempt to match the look as closely as possible with a standard_surface or standard_hair shader.

 

The HtoA material library can be found here.

 

Due to the large number of controls, the Standard Surface shader is split up into several groups. The individual settings for each group are described in more detail in the pages below. 

 

Further information about physically based rendering in Arnold can be found here.

Surface Normal Direction

When rendering diffuse surfaces it is very important that the normals of the geometry face in the right direction. In the example below you can see the difference between normals that are facing inwards in the wrong direction (left side) versus those that are facing correctly in the outwards direction (right side).