python点云投影样例，投影知识和理论分析见：三维点云投影（一）_Coding的叶子的博客-CSDN博客。
数据来源：modelnet40点云样例数据-深度学习文档类资源-CSDN下载。
一、python代码
# -*- coding: utf-8 -*-
"""
Created on Tue Apr 12 22:34:18 2022
@author: Administrator
"""
from mayavi import mlab
import numpy as np
def viz_mayavi(points):
x = points[:, 0] # x position of point
y = points[:, 1] # y position of point
z = points[:, 2] # z position of point
fig = mlab.figure(bgcolor=(0, 0, 0), size=(640, 360))
mlab.points3d(x, y, z,
y, # Values used for Color
mode="point",
colormap='spectral', # 'bone', 'copper', 'gnuplot'
# color=(0, 1, 0), # Used a fixed (r,g,b) instead
figure=fig,
)
mlab.show()
#定义平面方程Ax+By+Cz+D=0
#以z=0平面为例，即在xy平面上的投影A=0, B=0, C=1(任意值), D=0
#para[0, 0, 1, 0]
def point_project(points, para):
x = points[:, 0] # x position of point
y = points[:, 1] # y position of point
z = points[:, 2] # z position of point
d = para[0]**2 + para[1]**2 + para[2]**2
t = -(para[0]*x + para[1]*y + para[2]*z + para[3])/d
x = para[0]*t + x
y = para[1]*t + y
z = para[2]*t + z
return np.array([x, y, z]).T
#矩阵写法
#定义平面方程Ax+By+Cz+D=0
#以z=0平面为例，即在xy平面上的投影A=0, B=0, C=1(任意值), D=0
#para[0, 0, 1, 0]
def point_project_array(points, para):
para = np.array(para)
d = para[0]**2 + para[1]**2 + para[2]**2
t = -(np.matmul(points[:, :3], para[:3].T) + para[3])/d
points = np.matmul(t[:, np.newaxis], para[np.newaxis, :3]) + points[:, :3]
return points
if __name__ == '__main__':
points = np.loadtxt('airplane_0001.txt', delimiter=',')
#显示原始点云
#viz_mayavi(points)
#定义平面方程Ax+By+Cz+D=0
#以z=0平面为例，即在xy平面上的投影A=0, B=0, C=1(任意值), D=0
project_pane = [0, 0, 1, 0]
points_new = point_project_array(points, project_pane)
viz_mayavi(points_new)
二、图片展示结果
投影图片：
?
原始图片：
?
