A comparison of functional summary statistics to detect anisotropy of   three-dimensional point patterns
  The growing availability of three-dimensional point process data asks for a development of suitable analysis techniques. In this paper, we focus on two recently developed summary statistics, the conical and the cylindrical $K$-function, which may be used to detect anisotropies in 3D point patterns. We give some recommendations on choosing their arguments and investigate their ability to detect two special types of anisotropy. Finally, both functions are compared on some real data sets from neuroscience and glaciology. 
Farzaneh Safavimanesh, Claudia Redenbach
stat.ME