• Acta Optica Sinica
  • Vol. 42, Issue 12, 1212005 (2022)
Zhi Zhao1、*, Yanxin Ma2, Ke Xu1, and Jianwei Wan1
Author Affiliations
  • 1College of Electronic Science, National University of Defense Technology, Changsha 410073, Hunan, China
  • 2College of Meteorology and Oceanography, National University of Defense Technology, Changsha 410073, Hunan, China
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    DOI: 10.3788/AOS202242.1212005 Cite this Article Set citation alerts
    Zhi Zhao, Yanxin Ma, Ke Xu, Jianwei Wan. Optimized Scalable and Learnable Binary Quantization Network for LiDAR Point Cloud[J]. Acta Optica Sinica, 2022, 42(12): 1212005 Copy Citation Text show less
    General framework for point cloud learnable binary quantization network model
    Fig. 1. General framework for point cloud learnable binary quantization network model
    Learnable binary quantization network model of PointNet
    Fig. 2. Learnable binary quantization network model of PointNet
    Gene-algorithm based binary quantization scale factor recovery
    Fig. 3. Gene-algorithm based binary quantization scale factor recovery
    Optimal search of scale factor based on gene-algorithm optimization
    Fig. 4. Optimal search of scale factor based on gene-algorithm optimization
    Curves of feature entropy before and after pooling. (a) n=5; (b) n=20; (c) n=50; (d) n=100
    Fig. 5. Curves of feature entropy before and after pooling. (a) n=5; (b) n=20; (c) n=50; (d) n=100
    Minimization of statistically self-adaptive pooling loss. (a) Quantitative network self-regulation; (b) statistical knowledge transfer regulation of full precision network
    Fig. 6. Minimization of statistically self-adaptive pooling loss. (a) Quantitative network self-regulation; (b) statistical knowledge transfer regulation of full precision network
    Comparison of adjusted feature probability distributions. (a) Feature distribution comparison 1; (b) feature distribution comparison 2; (c) feature distribution comparison 3
    Fig. 7. Comparison of adjusted feature probability distributions. (a) Feature distribution comparison 1; (b) feature distribution comparison 2; (c) feature distribution comparison 3
    Learnable training process
    Fig. 8. Learnable training process
    Comparison of optimized pooling. (a) Quantization network self-adjustment; (b) full-precision network transfer adjustment
    Fig. 9. Comparison of optimized pooling. (a) Quantization network self-adjustment; (b) full-precision network transfer adjustment
    Training performance comparison. (a) Comparison result 1; (b) comparison result 2; (c) comparison result 3
    Fig. 10. Training performance comparison. (a) Comparison result 1; (b) comparison result 2; (c) comparison result 3
    Scaling factor searching based on gene-optimized algorithm. (a) Iterative searching process; (b) feature maps produced by binary conv layer
    Fig. 11. Scaling factor searching based on gene-optimized algorithm. (a) Iterative searching process; (b) feature maps produced by binary conv layer
    Comparison of different channel feature maps of different binary convolution layers (sub-figures from left to right are 3 corresponding channels in sequence). (a) Feature maps of different channels of 1st binary convolution layer; (b) feature maps of different channels of 2nd binary convolution layer; (c) feature maps of different channels of 3rd binary convolution layer
    Fig. 12. Comparison of different channel feature maps of different binary convolution layers (sub-figures from left to right are 3 corresponding channels in sequence). (a) Feature maps of different channels of 1st binary convolution layer; (b) feature maps of different channels of 2nd binary convolution layer; (c) feature maps of different channels of 3rd binary convolution layer
    Comparison of feature maps of binary convolution layers at different locations (sub-figures from left to right are 3 convolution layers in sequence). (a) Feature map of location 1; (b) feature map of location 2; (c) feature map of location 3
    Fig. 13. Comparison of feature maps of binary convolution layers at different locations (sub-figures from left to right are 3 convolution layers in sequence). (a) Feature map of location 1; (b) feature map of location 2; (c) feature map of location 3
    Feature maps of pooling. (a) Activation features before pooling; (b) pooling features of non-optimized binary network; (c) pooling features of binary network with pooling optimization; (d) pooling features of binary network with scaling and pooling optimization
    Fig. 14. Feature maps of pooling. (a) Activation features before pooling; (b) pooling features of non-optimized binary network; (c) pooling features of binary network with pooling optimization; (d) pooling features of binary network with scaling and pooling optimization
    Partial results of part segmentation. (a) Knife; (b) motorbike; (c) lamp
    Fig. 15. Partial results of part segmentation. (a) Knife; (b) motorbike; (c) lamp
    Partial results of semantic segmentation. (a) Area 1_Conference Room 2; (b) Area 1_Office Room 2; (c) Area 1_Hallway 1
    Fig. 16. Partial results of semantic segmentation. (a) Area 1_Conference Room 2; (b) Area 1_Office Room 2; (c) Area 1_Hallway 1
    Overall performance comparisons. (a) Performance comparison 1; (b) performance comparison 2
    Fig. 17. Overall performance comparisons. (a) Performance comparison 1; (b) performance comparison 2
    Inference time comparisons
    Fig. 18. Inference time comparisons
    MethodBit width Nw /bitBit width Na/bitScaling/ShiftingfactorFloating pointcalculationBitwisecalculation
    BNN110O1×O2
    XNOR-Net11ScalingO1O1×O2
    IRNet11Shifting0O1×O2+O1
    BiPointNet11ScalingO1O1×O2
    Pooling shiftingS0
    ScalingO1O1×O2
    Proposed model11Pooling shiftingS0
    Pooling scalingS0
    Table 1. Comparison of binary quantization algorithms
    MethodPooling typeBit width Nw /bitBit width Na /bitPrecision Pc /%
    Full precisionMAX323288.2
    BNNMAX1126.8
    IRNetMAX1118.5
    XNOR-NetMAX1171.8
    BiPointNetMAX114.1
    Proposed method (Hist)MAX1179.9
    Proposed method (KDE)MAX1180.2
    Proposed method (KNN)MAX1181.7
    Table 2. Comparison of binary quantization methods without optimized pooling
    MethodPooling typeBit width Nw /bitBit width Na /bitPrecision Pc /%
    Full precisionMAX323288.2
    MAX1126.8
    BNNAPSS1*1180.2
    APSS2*1178.1
    MAX1118.5
    IRNetAPSS1*1182.3
    APSS2*1180.7
    MAX1171.8
    XNOR-NetAPSS1*1186.0
    APSS2*1185.6
    MAX114.1
    BiPointNetAPSS1*1181.3
    APSS2*1182.7
    Table 3. Comparison of binary quantization methods with optimized pooling
    MethodPooling typeBit width Nw /bitBit width Na /bitPrecision Pc /%
    Full precisionMAX323288.2
    BNNMAX1126.8
    XNOR-NetMAX1171.8
    IRNetMAX1118.5
    BiPointNetEMA1186.1
    Proposed method (Hist)APSS1*1186.5
    APSS2*1185.3
    Proposed method (KDE)APSS1*1187.5
    APSS2*1187.3
    Proposed method (KNN)APSS1*1186.6
    APSS2*1187.4
    Table 4. Comparison of typical binary quantization methods
    MethodAeroBagCaCarChairEarphoneGuitarKnifeLampLaptopMotor-bikeMugPistolRocketSkateboardTable
    Fullprecision83.189.095.278.390.478.193.392.981.997.970.795.981.657.474.881.5
    BiPointNet79.669.686.367.588.669.887.583.375.095.345.191.676.847.957.579.6
    Proposedmodel80.264.887.066.887.077.689.784.376.396.750.292.379.650.166.280.1
    Table 5. Precision of part segmentation%
    MethodOverallmIoUOverall accmIoU/accof area1mIoU/accof area2mIoU/accof area3mIoU/accof area4mIoU/accof area5mIoU/accof area6
    Fullprecision51.982.059.7/85.134.7/73.660.9/87.243.6/80.943.1/82.066.2/88.1
    BiPointnet43.476.350.1/77.929.7/69.853.3/81.636.2/73.336.5/77.057.8/82.4
    Proposedmodel43.977.551.8/78.927.1/68.355.1/83.237.5/75.136.9/78.859.1/84.0
    MethodIoU ofceilingIoU offloorIoU ofwallIoU ofbeamIoU ofcolumnIoU ofwindowIoU ofdoorIoU oftableIoU ofchairIoU ofsofaIoU ofbookcaseIoU ofboardIoU ofclutter
    Fullprecision89.793.771.050.234.052.953.456.746.69.538.536.441.3
    BiPointNet84.285.662.032.822.941.747.345.239.59.135.325.833.2
    Proposedmodel85.086.360.333.724.243.446.546.641.18.734.226.534.7
    Table 6. Semantic segmentation experiment results%
    MethodsBit width Nw /bitBit width Na /bitPrecision Pc /%
    Full precision323288.2
    PointNetBiPointNet1186.1
    Proposed method1187.2
    Full precision323290.7
    PointNet++BiPointNet1188.5
    Proposed method1189.0
    Full precision323289.7
    PointCNNBiPointNet1181.5
    Proposed method1182.8
    Full precision323290.9
    DGCNNBiPointNet1175.0
    Proposed method1183.6
    Table 7. Comparative experiment results for typical network models
    MethodPooling typeFLOP persample /MbitSpeedup ratioSrParameter Pa /MbitCompressionratio Cr
    Full precisionMAX443.3813.481
    MAX8.35530.1523
    BNNAPSS1*10.45420.1523
    APSS2*12.56350.1523
    MAX8.94500.1622
    IRNetAPSS1*11.05400.1622
    APSS2*13.15340.1622
    MAX9.89450.626
    XNOR-NetAPSS1*11.99370.626
    APSS2*14.09310.626
    EMA10.56420.1523
    BiPointNetAPSS1*10.56420.1523
    APSS2*12.66350.1523
    MAX8.46520.1523
    Proposed modelAPSS1*10.56420.1523
    APSS2*12.66350.1523
    Table 8. Complexity comparison results
    Zhi Zhao, Yanxin Ma, Ke Xu, Jianwei Wan. Optimized Scalable and Learnable Binary Quantization Network for LiDAR Point Cloud[J]. Acta Optica Sinica, 2022, 42(12): 1212005
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