I’ve added a new article, Blending in Detail, written together with Colin Barré-Brisebois, on the topic of blending normal maps. We go through various techniques that are out there, as well as a neat alternative (“Reoriented Normal Mapping”) from Colin that I helped to optimise.
This is by no means a complete analysis – particularly as we focus on detail mapping – so we might return to the subject at a later date and tie up some loose ends. In the meantime, I hope you find the article useful. Please let us know in the comments!