【学习笔记】使用python带时间戳提取rosbag中的图像和雷达数据

使用sick的TIM561雷达采集数据，topic nam是/scan，摄像头录制图像，topic name是/usb_cam/image_raw。脚本如下：

# coding:utf-8
#!/usr/bin/python
 
# Extract images from a bag file.
 
#PKG = 'beginner_tutorials'
import roslib;   #roslib.load_manifest(PKG)
import rosbag
import rospy
import cv2
import os
from sensor_msgs.msg import Image
from cv_bridge import CvBridge
from cv_bridge import CvBridgeError
 
# Reading bag filename from command line or roslaunch parameter.
#import os
#import sys
 
rgb_path = '/home/kanghao/bagfiles/bag_image/'
laser_path= '/home/kanghao/bagfiles/laser_data/'
 
class ImageCreator():
    def __init__(self):
        self.bridge = CvBridge()
        with rosbag.Bag('/home/kanghao/bagfiles/2019-02-19-15-23-09.bag', 'r') as bag:  #要读取的bag文件；
            for topic,msg,t in bag.read_messages():
                if topic == "/usb_cam/image_raw": #图像的topic；
                        try:
                            cv_image = self.bridge.imgmsg_to_cv2(msg,"bgr8")
                        except CvBridgeError as e:
                            print(e)
                        timestr = "%.6f" %  msg.header.stamp.to_sec()
                        #%.6f表示小数点后带有6位，可根据精确度需要修改；
                        image_name = timestr+ ".png" #图像命名：时间戳.png
                        cv2.imwrite(rgb_path + image_name, cv_image)  #保存；
                elif topic == "/scan": #laser的topic；
                        timestr = "%.6f" %  msg.header.stamp.to_sec()
                        laser_data_name = timestr + ".txt"
                        laser_data_path = os.path.join(laser_path, laser_data_name)
                        with open(laser_data_path, "w") as f:
                            f.write(str(msg))

if __name__ == '__main__':
    try:
        image_creator = ImageCreator()
    except rospy.ROSInterruptException:
        pass