1 简介
最近在做livox与rgb相机的外参标定，网上看了很多开源方法大对数是基于ros做的，由于对ros不太熟悉，所以先基于python写一个初始版本，以下是全部代码，后面有有时间再整理，相机的内参是使用matlab工具箱标定的，大致思路是将标定板的点云数据通过左右、上下的坐标替换，深度值转换为灰度值，进而得到灰度图，对灰度图做传统图像处理，找到圆心，然后再逆转回在激光雷达坐标系上的坐标。
2 代码
powershell
import pandas as pd
import pcl
import open3d as o3d
import numpy as np
import cv2 as cv
import warnings
import xml
from sympy import false
warnings.filterwarnings("ignore")
rgb_mtx = np.array([[164.9671, 0., 334.1256,
0., 167.1601, 219.2284,
0., 0., 1.]]).reshape((3, 3))
rgb_dist = np.array([-0.0844, 0.0065, -2.2149e-04, -1.1157e-04, 2.8005e-04]).reshape((1, 5))
# rgb_mtx = np.array([[120, 0., 640,
# 0., 120, 360,
# 0., 0., 1.]]).reshape((3, 3))
# rgb_dist = np.zeros((5, 1), dtype=np.float64)
def find_lidar_blobs(input_img, show=False):
input_img = 255 - input_img
params = cv.SimpleBlobDetector_Params()
params.minThreshold = 5
# params.maxThreshold = 5
params.blobColor = 0
# Filter by Area.
params.filterByArea = True
params.minArea = 400
params.maxArea = 21000
# Filter by Circularity
params.filterByCircularity = True
params.minCircularity = 0.1
# Filter by Convexity
params.filterByConvexity = True
params.minConvexity = 0.87
# Filter by Inertia
params.filterByInertia = True
params.minInertiaRatio = 0.1
detector = cv.SimpleBlobDetector_create(params)
# keypoints是一个列表，其中的每个元素都是一个cv2.KeyPoint
# KeyPoint包含两个属性 圆的直径以及圆心的位置
keypoints = detector.detect(input_img)
# keypoints = [kp for kp in keypoints if 72 <= kp.size <= 88]
img_with_keypoints = cv.drawKeypoints(input_img, keypoints, np.array([]), (0,255,0), cv.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)
# size_list = [kp.size for kp in keypoints]
if show:
cv.namedWindow("Keypoints", 0)
cv.imshow('Keypoints', img_with_keypoints)
cv.waitKey(0)
cv.destroyAllWindows()
return keypoints
def filter_raw_pcl(data_path, color_change):
ori_pcl_data = pd.read_csv(data_path, low_memory=False)
x_condition = (ori_pcl_data['X'] > 0.6) & (ori_pcl_data['X'] <2) #纵向
y_condition = (ori_pcl_data['Y'] > -0.6) & (ori_pcl_data['Y'] < 0.5) #横向
z_condition = (ori_pcl_data['Z'] > 0.3) & (ori_pcl_data['Z'] < 3) #高度
ref_condition = (ori_pcl_data['Reflectivity'] > 0) & (ori_pcl_data['Reflectivity'] < 15)
# ref_condition = (ori_pcl_data['Reflectivity'] > 10)
filtered_data = ori_pcl_data[x_condition & y_condition & z_condition & ref_condition]
# filtered_data = ori_pcl_data[x_condition & y_condition & z_condition]
if color_change:
min = filtered_data['Reflectivity'].min()
max = filtered_data['Reflectivity'].max()
filtered_data['reflectance_normalized'] = (filtered_data['Reflectivity'] - min) / (max - min)
return filtered_data
def show_pcl(data):
point_cloud = o3d.geometry.PointCloud()
# 根据数据类型显示
if isinstance(data, pd.DataFrame):
point_cloud.points = o3d.utility.Vector3dVector(data[['X', 'Y', 'Z']].values)
else:
point_cloud.points = o3d.utility.Vector3dVector(data)
o3d.visualization.draw_geometries([point_cloud])
def sac_plane(valid_data_df):
valid_data = valid_data_df[['X', 'Y', 'Z']].values.astype('float32')
cloud = pcl.PointCloud(valid_data)
seg = cloud.make_segmenter()
seg.set_optimize_coefficients(True)
seg.set_model_type(pcl.SACMODEL_PLANE)
seg.set_method_type(pcl.SAC_RANSAC)
seg.set_distance_threshold(0.01)
inliners, coefficients = seg.segment()
guess = np.expand_dims(np.array(coefficients), axis=1)
res = np.dot(valid_data, guess[:3, :]) + guess[3, 0]
plane_cloud = cloud.extract(inliners, negative=False)
plane_cloud_arr = plane_cloud.to_array()
return plane_cloud_arr, coefficients
def projecto2D(filter_data):
projected_points = filter_data*1000
x_min, x_max = projected_points[:, 0].min(), projected_points[:, 0].max()
z_min, z_max = projected_points[:, 2].min(), projected_points[:, 2].max()
y_min, y_max = projected_points[:, 1].min(), projected_points[:, 1].max()
x_range = x_max -x_min
# 创建RGB图像
image_width = int(y_max - y_min)
image_height = int(z_max - z_min)
# TODO 当前是用int8保存深度值 后面使用float16格式
rgb_image = np.zeros((image_height, image_width, 1), dtype=np.uint8)
# 映射颜色到RGB图像
for point in projected_points:
y, z = int(y_max -point[1]), int(z_max - point[2])
if 0 <= y < image_width and 0 <= z < image_height:
rgb_image[z, y] = int(255*(point[0]- x_min)/x_range)
cv.imwrite("demo.jpg", rgb_image)
return[x_min, x_range, y_max, z_max], rgb_image
def cal_rgbd(img_path, xyz, show=False):
if isinstance(img_path, str):
ori_img = cv.imread(img_path, cv.IMREAD_UNCHANGED)
else:
ori_img = img_path
img_show = cv.cvtColor(ori_img, cv.COLOR_GRAY2BGR)
# 图片二值化
ret, smoothed_img = cv.threshold(ori_img, 15, 255, cv.THRESH_BINARY)
kernel = np.ones((5,5),np.uint8)
smoothed_img = cv.dilate(smoothed_img,kernel,iterations = 1)
if show:
cv.namedWindow('threshold', 0)
cv.imshow("threshold", smoothed_img)
key = 0
while True:
key = cv.waitKey()
if key == 27:
break
# 高斯滤波
smoothed_img = cv.GaussianBlur(smoothed_img, (5, 5), 0)
keypoints = find_lidar_blobs(smoothed_img, show= show)
gridcell_list = []
for keypoint in keypoints:
x, z = int(keypoint.pt[0]), int(keypoint.pt[1])
valid_point_num = 0
value_sum = 0
for i in range(10):
for j in range(10):
# 加入距离筛选
# TODO 现在深度值有问题 深度值从左到右递减
if(ori_img[z+j, x+i]) > 30:
valid_point_num += 1
value_sum += ori_img[z+j, x+i]
if valid_point_num == 0:
continue
mean_value = value_sum / valid_point_num
# 还原为之前的深度值
mean_value_trans = mean_value*xyz[1]/255 + xyz[0]
# print("mean_value_trans", mean_value_trans)
if isinstance(mean_value_trans, np.ndarray):
mean_value_trans = mean_value_trans.item()
# return[x_min, x_range, y_max, z_max], rgb_image
x_trans= xyz[2] - x
z_trans = xyz[3] -z
if z_trans > 400: #在纵向上加入高度筛选
gridcell_list.append([mean_value_trans,x_trans,z_trans])
cv.circle(img_show,(x, z), 1, (0, 0, 255))
if show:
cv.namedWindow("img_show", 0)
cv.imshow('img_show', img_show)
key = 0
while True:
key = cv.waitKey()
if key == 27:
break
return np.array(gridcell_list, dtype=np.float64)
def add_world_point(circle_dist=8,boardh=12, boardw=4):
world_points = []
for i in range(boardh):
for j in range(boardw):
if i%2 == 0:
x = circle_dist * (2 * j)
else:
x = circle_dist * (2 * j + 1)
y = circle_dist * i
world_points.append([x, y, 0])
return np.array(world_points, dtype=np.float32)
def find_rgb_blobs(input_img, show=False):
params = cv.SimpleBlobDetector_Params()
params.minThreshold = 5
# params.maxThreshold = 5
# params.blobColor = 0
# Filter by Area.
params.filterByArea = True
params.minArea = 20
params.maxArea = 500
# Filter by Circularity
params.filterByCircularity = True
params.minCircularity = 0.1
# Filter by Convexity
params.filterByConvexity = True
params.minConvexity = 0.87
# Filter by Inertia
params.filterByInertia = True
params.minInertiaRatio = 0.1
detector = cv.SimpleBlobDetector_create(params)
keypoints = detector.detect(input_img)
img_with_keypoints = cv.drawKeypoints(input_img, keypoints, np.array([]), (0,255,0), cv.DRAW_MATCHES_FLAGS_DRAW_RICH_KEYPOINTS)
# size_list = [kp.size for kp in keypoints]
if show:
cv.namedWindow("Keypoints", 0)
cv.imshow('Keypoints', img_with_keypoints)
cv.waitKey(0)
cv.destroyAllWindows()
return keypoints
def cal_rgb(rgb_img_path, show=False):
rgb_cell_list = []
rgb_img = cv.imread(rgb_img_path)
gray = cv.cvtColor(rgb_img,cv.COLOR_BGR2GRAY)
rgb_img[0:100, :] = 0
rgb_img[:, 0:250] = 0
rgb_img[250:480, :] = 0
rgb_img[:, 400:] = 0
keypoints = find_rgb_blobs(rgb_img, show=show)
for keypoint in keypoints:
x, y = int(keypoint.pt[0]), int(keypoint.pt[1])
rgb_cell_list.append([x, y])
rgb_cell_list = np.array(rgb_cell_list)
ori = np.copy(rgb_cell_list)
# 当前的rgb已经严格按照从上到下，从左到右排列
ori[:, 1] = np.round(ori[:, 1] / 8) * 8
indices = np.lexsort((ori[:, 0], ori[:, 1]))
rgb_cell_list = rgb_cell_list[indices]
# word_points = add_world_point()
# if show:
# i = 0
# for point in rgb_cell_list:
# cv.putText(rgb_img, "{}".format(i), (point[0], point[1]), cv.FONT_HERSHEY_TRIPLEX,thickness = 1,fontScale= 0.5,color=(0,255,0))
# i = i + 1
# cv.namedWindow("img_show_whole", 0)
# cv.imshow('img_show_whole', rgb_img)
# key = 0
# while True:
# key = cv.waitKey()
# if key == 27:
# break
# rgb_cell_list = np.array(rgb_cell_list, dtype=np.float32).reshape(1, -1, 2)
# word_points = np.array(word_points).reshape(1, -1, 3)
# ret, mtx, dist, rvecs, tvecs = cv.calibrateCamera(word_points, rgb_cell_list, gray.shape[::-1], None, None)
# if ret:
# print(mtx, dist)
rgb_cell_list = rgb_cell_list.tolist()[:12]
return np.array(rgb_cell_list, dtype=np.float64)
def getRT(world_points,gridcell_list, mtx, dist):
_, rvec, tvec = cv.solvePnP(world_points,
gridcell_list, mtx, dist,cv.SOLVEPNP_ITERATIVE)
rotation_m, _ = cv.Rodrigues(rvec) # 罗德里格斯变换
RT = np.transpose(rotation_m)
shouldBeIdentity = np.dot(RT, rotation_m)
I = np.identity(3, dtype=rotation_m.dtype)
n = np.linalg.norm(I - shouldBeIdentity)
assert (n < 1e-6)
return rotation_m, tvec
def main():
show = True
data_path = '~/cxx_project/lidar_rgb_calib/data/0221/2024-02-21_18-06-03.Csv'
filter_data = filter_raw_pcl(data_path, False)
# show_pcl(filter_data)
calib_board, conf = sac_plane(filter_data)
xyz, depth_img = projecto2D(calib_board)
depth_cell_list = cal_rgbd(depth_img, xyz, show=show)
depth_ori = np.copy(depth_cell_list)
# # 当前的rgb已经严格按照从上到下，从左到右排列
depth_ori[:, 2] = np.round(depth_ori[:, 2] / 60) * 60
indices = np.lexsort((-depth_ori[:, 1], -depth_ori[:, 2]))
depth_cell_list = depth_cell_list[indices]/1000
# depth_cell_list = depth_cell_list[:, [0, 2, 1]]
print("depth_cell_list:", depth_cell_list)
rgb_img_path = '~/cxx_project/lidar_rgb_calib/data/0221/BIAODINGBAN/undistort_img/52.jpg'
img = cv.imread(rgb_img_path)
rgb_cell_list = cal_rgb(rgb_img_path, show=show)
print("rgb_cell_list:", rgb_cell_list)
R, T= getRT(depth_cell_list, rgb_cell_list, rgb_mtx, rgb_dist)
print("R:{}, T{}".format(R, T))
image_points, _ = cv.projectPoints(calib_board, R, T, rgb_mtx, rgb_dist)
for point in image_points:
x, y = point[0]
cv.circle(img, (int(x), int(y)), radius=1, color=(0, 255, 0), thickness=-1)
# if show:
cv.namedWindow("res", 0)
cv.imshow('res', img)
cv.waitKey(0)
# cv.destroyAllWindows()
if __name__ == "__main__":
main()