about making my own datasets

[tianzhijiaozi0511]

hi!
I want to make my own segmentation datasets like S3DIS or Paris-Lille-3D. As the description in the paper " The 3D scenes in
these datasets are too big to be segmented as a whole.Our KP-FCNN architecture is used to segment small subclouds contained in spheres."
How can i get the small sub clouds?