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Open3d计算点云法向量，可视化（代码）

article 2025/3/16 1:18:01

Open3d使用estimate_normals函数来计算法向量。其参数设置Open3d提供了3中参数搜索的方法（所有计算的法向量模长为1）：

open3d.geometry.KDTreeSearchParamKNN(knn=20)                        # 计算近邻的20个点
open3d.geometry.KDTreeSearchParamRadius(radius=0.01)                # 计算指定半径内的点
open3d.geometry.KDTreeSearchParamHybrid(radius=0.01, max_nn=20)     # 同时考虑搜索半径和近邻点个数

Open3d绘制点云draw_geometries的参数说明：

def draw_geometries(*args, **kwargs): # real signature unknown; restored from __doc__
    """
    draw_geometries(*args, **kwargs)
    Overloaded function.
   
   
    1. draw_geometries(geometry_list, window_name='Open3D', width=1920, height=1080, left=50, top=50, point_show_normal=False, mesh_show_wireframe=False, mesh_show_back_face=False)
        Function to draw a list of geometry.Geometry objects
   
    Args:
        geometry_list (List[open3d.geometry.Geometry]): List of geometries to be visualized.
        window_name (str, optional, default='Open3D'): The displayed title of the visualization window.
        width (int, optional, default=1920): The width of the visualization window.
        height (int, optional, default=1080): The height of the visualization window.
        left (int, optional, default=50): The left margin of the visualization window.
        top (int, optional, default=50): The top margin of the visualization window.
        point_show_normal (bool, optional, default=False): Visualize point normals if set to true.
        mesh_show_wireframe (bool, optional, default=False): Visualize mesh wireframe if set to true.
        mesh_show_back_face (bool, optional, default=False): Visualize also the back face of the mesh triangles.
   
    Returns:
        None
   
    2. draw_geometries(geometry_list, window_name='Open3D', width=1920, height=1080, left=50, top=50, point_show_normal=False, mesh_show_wireframe=False, mesh_show_back_face=False, lookat, up, front, zoom)
        Function to draw a list of geometry.Geometry objects
   
    Args:
        geometry_list (List[open3d.geometry.Geometry]): List of geometries to be visualized.
        window_name (str, optional, default='Open3D'): The displayed title of the visualization window.
        width (int, optional, default=1920): The width of the visualization window.
        height (int, optional, default=1080): The height of the visualization window.
        left (int, optional, default=50): The left margin of the visualization window.
        top (int, optional, default=50): The top margin of the visualization window.
        point_show_normal (bool, optional, default=False): Visualize point normals if set to true.
        mesh_show_wireframe (bool, optional, default=False): Visualize mesh wireframe if set to true.
        mesh_show_back_face (bool, optional, default=False): Visualize also the back face of the mesh triangles.
        lookat (numpy.ndarray[numpy.float64[3, 1]]): The lookat vector of the camera.
        up (numpy.ndarray[numpy.float64[3, 1]]): The up vector of the camera.
        front (numpy.ndarray[numpy.float64[3, 1]]): The front vector of the camera.
        zoom (float): The zoom of the camera.
   
    Returns:
        None
    """
    pass

法向量计算与可视化代码：

import open3d
import numpy as np
import mayavi.mlab as mlab
# 4. 法向量的计算
def open3d_vector_compute():
    pcd_path = r"E:\xxxx\open3d_xxxx\ICP_data\cloud_bin_0.pcd"
    pcd = open3d.io.read_point_cloud(pcd_path)
    pcd.estimate_normals(
        search_param=open3d.geometry.KDTreeSearchParamHybrid(radius=0.01, max_nn=30)
    )
    normals = np.array(pcd.normals)    # 法向量结果与点云维度一致(N, 3)
    points = np.array(pcd.points)
    print(normals.shape, points.shape)
    # 验证法向量模长为1(模长会有一定的偏差，不完全为1)
    normals_length = np.sum(normals**2, axis=1)
    flag = np.equal(np.ones(normals_length.shape, dtype=float), normals_length).all()
    print('all equal 1:', flag)
    # 法向量可视化
    open3d.visualization.draw_geometries([pcd],
                                         window_name="Open3d",
                                         point_show_normal=True,
                                         width=800,   # 窗口宽度
                                         height=600)  # 窗口高度
if __name__ == '__main__':
    open3d_vector_compute()