Forest resource management and ecological assessment have been recently supported by emerging technologies.Terrestrial laser scanning(TLS)is one that can be quickly and accurately used to obtain three-dimensional fore...Forest resource management and ecological assessment have been recently supported by emerging technologies.Terrestrial laser scanning(TLS)is one that can be quickly and accurately used to obtain three-dimensional forest information,and create good representations of forest vertical structure.TLS data can be exploited for highly significant tasks,particularly the segmentation and information extraction for individual trees.However,the existing single-tree segmentation methods suffer from low segmentation accuracy and poor robustness,and hence do not lead to satisfactory results for natural forests in complex environments.In this paper,we propose a trunk-growth(TG)method for single-tree point-cloud segmentation,and apply this method to the natural forest scenes of Shangri-La City in Northwest Yunnan,China.First,the point normal vector and its Z-axis component are used as trunk-growth constraints.Then,the points surrounding the trunk are searched to account for regrowth.Finally,the nearest distributed branch and leaf points are used to complete the individual tree segmentation.The results show that the TG method can effectively segment individual trees with an average F-score of 0.96.The proposed method applies to many types of trees with various growth shapes,and can effectively identify shrubs and herbs in complex scenes of natural forests.The promising outcomes of the TG method demonstrate the key advantages of combining plant morphology theory and LiDAR technology for advancing and optimizing forestry systems.展开更多
An approach is presented to generate rough interference-free tool-paths directly from massive unorganized data in rough machining that is performed by machining volumes of material in a slice-by-slice manner.Unorganiz...An approach is presented to generate rough interference-free tool-paths directly from massive unorganized data in rough machining that is performed by machining volumes of material in a slice-by-slice manner.Unorganized point-cloud is firstly converted to cross-section data.Then a robust data-structure named tool-path net is constructed to save tool-path data.Optimal algorithms for partitioning sub-cut-areas and computing interference-free cutter-locations are put forward.Finally the tool-paths are linked in a zigzag milling mode,which can be transformed into a traveling sales man problem.The experiment indicates optimal tool paths can be acquired,and high computation efficiency can be obtained and interference can be avoided successfully.展开更多
针对自动驾驶场景下,近处干扰点云误检率高、远处稀疏点云漏检率高的问题,提出了一种基于改进PointPillars的自动驾驶障碍物点云检测算法.首先,通过聚合模块和共享多层感知机(shared multi-layer perceptron,MLP)对柱体内点云进行特征编...针对自动驾驶场景下,近处干扰点云误检率高、远处稀疏点云漏检率高的问题,提出了一种基于改进PointPillars的自动驾驶障碍物点云检测算法.首先,通过聚合模块和共享多层感知机(shared multi-layer perceptron,MLP)对柱体内点云进行特征编码,采用最大池化与平均池化叠加的方法将点云的显著特征与细节特征映射为柱体特征;其次,针对算法对伪图特征关注与利用不充分的问题,引入坐标注意力(coordinate attention,CA)机制和残差连接的伪图特征提取模块(attention and residual second block,ARSB),将深层与浅层特征图进行融合,优化算法梯度,增强算法对有效目标的关注度.试验结果表明:改进算法对全局点云检测精度较高,平均精度优于PointPillars、稀疏到稠密3D目标检测器(STD)等点云目标检测算法,在汽车类别上的检测精度优势明显,检测速度较快,符合实时性要求.展开更多
针对复杂地理实体建模中,多模态点云数据融合处理耗时、精度偏差较大等问题,本文以南通大剧院异形建筑三维建模为例,提出一种多模态控制点辅助约束的最近点迭代算法(Multimodal Control Point Assistant-Iterative Closest Point)对点...针对复杂地理实体建模中,多模态点云数据融合处理耗时、精度偏差较大等问题,本文以南通大剧院异形建筑三维建模为例,提出一种多模态控制点辅助约束的最近点迭代算法(Multimodal Control Point Assistant-Iterative Closest Point)对点云数据进行配准,该算法能够实现复杂地理实体多模态点云数据的精确配准。通过实验对比,结果表明,与传统ICP算法、SAC-IA算法、NDT算法相比,本文算法不但能够快速实现全局收敛,而且可以满足城市级三维建模精度要求。展开更多
基金The work was supported by the National Natural Science Foundation of China(Grant Number 41961060)the Key Program of Basic Research of Yunnan Province,China(Grant Number 2019FA017)+1 种基金the Multi-government International Science and Technology Innovation Cooperation Key Project of National Key Research and Development Program of China(Grant Number 2018YFE0184300)the Program for Innovative Research Team in Science and Technology research and innovation fund(ysdyjs 2020058)in the University of Yunnan Province.
文摘Forest resource management and ecological assessment have been recently supported by emerging technologies.Terrestrial laser scanning(TLS)is one that can be quickly and accurately used to obtain three-dimensional forest information,and create good representations of forest vertical structure.TLS data can be exploited for highly significant tasks,particularly the segmentation and information extraction for individual trees.However,the existing single-tree segmentation methods suffer from low segmentation accuracy and poor robustness,and hence do not lead to satisfactory results for natural forests in complex environments.In this paper,we propose a trunk-growth(TG)method for single-tree point-cloud segmentation,and apply this method to the natural forest scenes of Shangri-La City in Northwest Yunnan,China.First,the point normal vector and its Z-axis component are used as trunk-growth constraints.Then,the points surrounding the trunk are searched to account for regrowth.Finally,the nearest distributed branch and leaf points are used to complete the individual tree segmentation.The results show that the TG method can effectively segment individual trees with an average F-score of 0.96.The proposed method applies to many types of trees with various growth shapes,and can effectively identify shrubs and herbs in complex scenes of natural forests.The promising outcomes of the TG method demonstrate the key advantages of combining plant morphology theory and LiDAR technology for advancing and optimizing forestry systems.
文摘An approach is presented to generate rough interference-free tool-paths directly from massive unorganized data in rough machining that is performed by machining volumes of material in a slice-by-slice manner.Unorganized point-cloud is firstly converted to cross-section data.Then a robust data-structure named tool-path net is constructed to save tool-path data.Optimal algorithms for partitioning sub-cut-areas and computing interference-free cutter-locations are put forward.Finally the tool-paths are linked in a zigzag milling mode,which can be transformed into a traveling sales man problem.The experiment indicates optimal tool paths can be acquired,and high computation efficiency can be obtained and interference can be avoided successfully.
文摘针对自动驾驶场景下,近处干扰点云误检率高、远处稀疏点云漏检率高的问题,提出了一种基于改进PointPillars的自动驾驶障碍物点云检测算法.首先,通过聚合模块和共享多层感知机(shared multi-layer perceptron,MLP)对柱体内点云进行特征编码,采用最大池化与平均池化叠加的方法将点云的显著特征与细节特征映射为柱体特征;其次,针对算法对伪图特征关注与利用不充分的问题,引入坐标注意力(coordinate attention,CA)机制和残差连接的伪图特征提取模块(attention and residual second block,ARSB),将深层与浅层特征图进行融合,优化算法梯度,增强算法对有效目标的关注度.试验结果表明:改进算法对全局点云检测精度较高,平均精度优于PointPillars、稀疏到稠密3D目标检测器(STD)等点云目标检测算法,在汽车类别上的检测精度优势明显,检测速度较快,符合实时性要求.
文摘针对复杂地理实体建模中,多模态点云数据融合处理耗时、精度偏差较大等问题,本文以南通大剧院异形建筑三维建模为例,提出一种多模态控制点辅助约束的最近点迭代算法(Multimodal Control Point Assistant-Iterative Closest Point)对点云数据进行配准,该算法能够实现复杂地理实体多模态点云数据的精确配准。通过实验对比,结果表明,与传统ICP算法、SAC-IA算法、NDT算法相比,本文算法不但能够快速实现全局收敛,而且可以满足城市级三维建模精度要求。
