# HD-Tree: An Efficient High-Dimensional Virtual Index Structure Using a Half Decomposition Strategy
## Methodology
### Algorithms of HD-Tree
As a result, the half decomposition strategy of the HD-tree is reliable and effective. The virtual tree structure used by HD-tree determines that it can easily perform parallel access calculations for big data. Compared with the D-tree, the HD-tree proposed in this article has been greatly improved, reducing the number of nodes. Nevertheless, these improvements cannot solve the problem of high spatial complexity of the hash table. We intend to use the bloom filter to assist the hash table in judging whether integer encoding exists. **Author Contributions**: Conceptualization, Z.H., Z.W. and T.H. ; methodology, Z.W. and T.H. ; software, T.H. ; validation, Z.H., Z.W. and T.H. ; resources, G.L. ; writing-original draft preparation, T.H. ; writing-review and editing, G.L. and T.H. ; visualization, Z.W. and T.H. ; project administration, G.L. ; funding acquisition, G.L. All authors have read and agreed to the published version of the manuscript. **Funding**: The work described in this paper was supported by the National Natural Science Foundation of China (U1711267, 41572314, 41972306), Hubei Province Innovation Group Project (2019 CFA023) and Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (CUGCJ1810, CUG2019 ZR03). **Conflicts of Interest**: The authors declare no conflict of interest. ## References

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