import open3d as o3d
import numpy as np
pcd = o3d.io.read_point_cloud("pointcloud.pcd")

# 估计法线
pcd.estimate_normals(
    search_param=o3d.geometry.KDTreeSearchParamHybrid(
        radius=0.1,   # 搜索半径
        max_nn=30     # 最大邻居数
    )
)

# 可视化法线
o3d.visualization.draw_geometries([pcd], point_show_normal=True)

# 获取法线数据
normals = np.asarray(pcd.normals)