Algorithm 1 Collapsed Gibbs sampling for our HDPM model
1:	Initialization assign all the points as one cluster.
2:	repeat
3:	step1: sample bundle indicator cji using Eq (10).
4:	step2: sample voxel and orientation index Wji using Eq (5).
5:	step3: sample β using the approach proposed in (Teh et al., 2006).
6:	step4 (optional): sample concentration parameters α and γ using the approach proposed in (Teh et al., 2006).
7:	until converge or exceed the maximum iteration number