[CARLA] CARLA Simulator Lidar 데이터 저장

[김위제]

CARLA Simulator Lidar 데이터를 ply 형식으로 저장

패키지 작성

# 1. 패키지 생성
cd ~/ros2_ws/src
ros2 pkg create --build-type ament_python carla_lidar_saver --dependencies rclpy sensor_msgs sensor_msgs_py


# 빌드
colcon build --packages-select carla_lidar_saver
source install/setup.bash

ros2 run carla_lidar_saver saver

/carla_lidar_saver/carla_lidar_saver/carla_lidar_saver.py

import rclpy
from rclpy.node import Node
from sensor_msgs.msg import PointCloud2
import sensor_msgs_py.point_cloud2 as pc2
import open3d as o3d
import numpy as np
import os

class LidarSaver(Node):
def __init__(self):
super().__init__('lidar_to_ply_node')
self.subscription = self.create_subscription(
PointCloud2,
'/carla/hero/lidar',
self.listener_callback,
10)

self.save_path = './saved_ply'
if not os.path.exists(self.save_path):
os.makedirs(self.save_path)

self.count = 0
self.get_logger().info('LiDAR to PLY Saver Node has started.')

def listener_callback(self, msg):
# 1. PointCloud2 메시지를 numpy array로 변환 (x, y, z)
points = pc2.read_points_numpy(msg, field_names=("x", "y", "z"), skip_nans=True)

if points.shape[0] == 0:
return

# 2. Open3D 포인트 클라우드 객체 생성
pcd = o3d.geometry.PointCloud()
pcd.points = o3d.utility.Vector3dVector(points)

# 3. 모든 포인트에 흰색 입히기 (N, 3) 형태의 배열 생성
# Open3D의 색상은 0.0 ~ 1.0 사이의 값을 가집니다. (1, 1, 1은 흰색)
white_color = np.ones((points.shape[0], 3))
pcd.colors = o3d.utility.Vector3dVector(white_color)

# 50프레임마다 저장
if self.count % 1 == 0:
filename = os.path.join(self.save_path, f"lidar_{self.count:05d}.ply")
# write_ascii=False로 저장하면 용량이 적고 로딩이 빠릅니다.
o3d.io.write_point_cloud(filename, pcd)
self.get_logger().info(f'Saved with white color: {filename}')

self.count += 1

def main(args=None):
rclpy.init(args=args)
node = LidarSaver()
try:
rclpy.spin(node)
except KeyboardInterrupt:
pass
finally:
node.destroy_node()
rclpy.shutdown()

/carla_lidar_saver/carla_lidar_saver/viz_ply.py

import open3d as o3d
import os
import glob
import numpy as np

class LidarVisualizer:
def __init__(self, directory):
self.ply_files = sorted(glob.glob(os.path.join(directory, "*.ply")))
if not self.ply_files:
print(f"Error: No .ply files found in {directory}")
return

self.index = 0
self.total = len(self.ply_files)
print(f"Total {self.total} files found.")
print("Controls: [→]: Next, [←]: Previous, [Q/ESC]: Exit")

# 시각화 객체 생성 (Key Callback 지원)
self.vis = o3d.visualization.VisualizerWithKeyCallback()
self.vis.create_window(window_name="CARLA LiDAR Viewer (Arrow Keys)", width=1280, height=720)

# 초기 렌더링 설정
opt = self.vis.get_render_option()
opt.background_color = np.asarray([0, 0, 0]) # 검정 배경
opt.point_size = 1.0 # 점 크기

# 첫 번째 프레임 로드
self.pcd = o3d.io.read_point_cloud(self.ply_files[self.index])
self.vis.add_geometry(self.pcd)

# 방향키 콜백 등록 (GLFW 키 코드 기준)
# 262: 오른쪽, 263: 왼쪽
self.vis.register_key_callback(262, self.load_next)
self.vis.register_key_callback(263, self.load_prev)

self.vis.run()
self.vis.destroy_window()

def update_view(self):
# 새로운 데이터 로드
new_pcd = o3d.io.read_point_cloud(self.ply_files[self.index])

# 기존 geometry 데이터 교체
self.pcd.points = new_pcd.points
self.pcd.colors = new_pcd.colors

# 화면 갱신
self.vis.update_geometry(self.pcd)
self.vis.set_full_screen(False) # 가끔 필요한 화면 리프레시 트리거
print(f"[{self.index + 1}/{self.total}] Visualizing: {os.path.basename(self.ply_files[self.index])}")

def load_next(self, vis):
self.index = (self.index + 1) % self.total
self.update_view()
return False

def load_prev(self, vis):
self.index = (self.index - 1) % self.total
self.update_view()
return False

def main(args=None):
PATH = "/home/airlab/ros2_ws/saved_ply"
if not os.path.exists(PATH):
print(f"Directory not found: {PATH}")
return

LidarVisualizer(PATH)

if __name__ == "__main__":
main()

/carla_lidar_saver/setup.py

from setuptools import find_packages, setup

package_name = 'carla_lidar_saver'

setup(
name=package_name,
version='0.0.0',
packages=find_packages(exclude=['test']),
data_files=[
('share/ament_index/resource_index/packages',
['resource/' + package_name]),
('share/' + package_name, ['package.xml']),
],
install_requires=['setuptools'],
zip_safe=True,
maintainer='airlab',
maintainer_email='airlab@todo.todo',
description='TODO: Package description',
license='TODO: License declaration',
extras_require={
'test': [
'pytest',
],
},
entry_points={
'console_scripts': [
'saver = carla_lidar_saver.carla_lidar_saver:main',
'viz = carla_lidar_saver.viz_ply:main',
],
},
)

/carla_lidar_saver/setup.cfg

[develop]
script_dir=$base/lib/carla_lidar_saver
[install]
install_scripts=$base/lib/carla_lidar_saver

saved_ply 폴더에 따로 저장됨

데이터 수집

GDK_BACKEND=x11 XDG_SESSION_TYPE=x11 ros2 run carla_lidar_saver saver 

시각화 

GDK_BACKEND=x11 XDG_SESSION_TYPE=x11 ros2 run carla_lidar_saver viz 

32ch

64ch

128ch