Fig. 1. Octree-like multi-layer index structure

Fig. 2. Schematic of the octree-like plane division

Fig. 3. Flowchart for establishing the octree-like index structure

Fig. 4. Schematic of linear coding

Fig. 5. Relationship between point and KD space

Fig. 6. Spatial segmentation schematic of octree. (a) Uniform segmentation; (b) nonuniform segmentation

Fig. 7. Local comparison of sampling effects under different spatial structures of Turbine Blade. (a) Random sampling; (b) KD-tree sampling; (c) octree index sampling; (d) quad+KD-tree sampling; (e) 3DOR^*-tree sampling; (f) octree-like sampling

Fig. 8. Local comparison of sampling effects under different spatial structures of Turbine Blade. (a) Random sampling; (b) KD-tree sampling; (c) octree index sampling; (d) quad+KD-tree sampling; (e) 3DOR^*-tree sampling; (f) octree-like sampling

Fig. 9. Local comparison of sampling effects under different spatial structures in Haloxylon. (a) Random sampling; (b) quad+KD-tree sampling; (c) 3DOR^*-tree sampling; (d) octree-like sampling

Fig. 10. Local comparison of sampling effects under different spatial structures of Haloxylon. (a) Random sampling; (b) quad+KD-tree sampling; (c) 3DOR^*-tree sampling; (d) octree-like sampling

Fig. 11. Comparison of indexing time under different KD thresholds

Fig. 12. Comparison of index memory usage under different KD thresholds