python三维模型法向量计算及注意事项

# -*- coding: utf-8 -*- ''' CSDN博客：https://blog.csdn.net/suiyingy 乐乐感知学堂公众号 长期分享三维、二维感知、大模型等AI算法和demo以及金融量化分析算法等。 本程序作用：open3d顶点法向量和表面法向量可视化 专栏地址：https://blog.csdn.net/suiyingy/category_12462636.html ''' import numpy as np import open3d as o3d if __name__ == '__main__': vertices = np.array([[0.0, 0.0, 1.0], [3.0, 0.0, 1.0], [0.0, 4.0, 1.0]]) faces = np.array([[1, 2, 3]]) faces = faces - 1 # 减1是因为索引从0开始 # 创建TriangleMesh对象 mesh = o3d.geometry.TriangleMesh() # 设置顶点和面片 mesh.vertices = o3d.utility.Vector3dVector(vertices) mesh.triangles = o3d.utility.Vector3iVector(faces) mesh.compute_triangle_normals() triangle_normals = np.array(mesh.triangle_normals) print('triangle normals 1: ', triangle_normals) mesh.compute_vertex_normals() vertex_normals = np.array(mesh.vertex_normals) print('vertex normals 1: ', vertex_normals) # 创建法向量的起点和终点 face_centers = np.mean(vertices[faces], axis=1) # 三角面中心 arrow_start_points = np.vstack((vertices, face_centers)) arrow_end_points = arrow_start_points + np.vstack((vertex_normals, triangle_normals)) * 0.5 # 0.1为法向量长度 # 创建法向量可视化的 LineSet 对象 line_set = o3d.geometry.LineSet() line_set.points = o3d.utility.Vector3dVector(np.concatenate([arrow_start_points, arrow_end_points], axis=0)) line_set.lines = o3d.utility.Vector2iVector(np.stack([np.arange(len(arrow_start_points)), np.arange(len(arrow_start_points)) + len(arrow_start_points)], axis=1)) line_colors = np.array([[0.0, 0.0, 1.0]] * len(arrow_start_points)) line_set.colors = o3d.utility.Vector3dVector(line_colors) # 创建坐标系可视化的 LineSet 对象 # 显示坐标系，xyz - rgb coordinate_frame = o3d.geometry.TriangleMesh.create_coordinate_frame(size=0.5, origin=[0, 0, 0]) # 可视化 Mesh、法向量和坐标系 o3d.visualization.draw_geometries([mesh, line_set, coordinate_frame]) # 创建箭头的 TriangleMesh 对象，使用箭头显示法向量 arrow_meshes = [] for i in range(len(arrow_start_points)): arrow_mesh = o3d.geometry.TriangleMesh.create_arrow(cylinder_height=0.8, cylinder_radius=0.01, cone_height=0.3, cone_radius=0.1) # 平移和旋转箭头，使其与线段匹配 arrow_center = (arrow_start_points[i] + arrow_end_points[i]) / 2 arrow_mesh.translate(arrow_start_points[i].T) vertex_colors = np.array([[0.0, 0.0, 1.0]] * len(arrow_mesh.vertices)) arrow_mesh.vertex_colors = o3d.utility.Vector3dVector(vertex_colors) arrow_meshes.append(arrow_mesh) # break # 可视化 Mesh、LineSet 和箭头 o3d.visualization.draw_geometries([mesh]+arrow_meshes+[coordinate_frame])