python程序发布和订阅ros话题

参考博客链接

编写talker.py:

这个文件调用了opencv打开摄像头获取图像并发布出去

#!/usr/bin/env python
# license removed for brevity
import rospy
from sensor_msgs.msg import Image
import cv2
from cv_bridge import CvBridge

def talker():
     pub = rospy.Publisher('/tutorial/image', Image, queue_size=1) 
     rospy.init_node('talker', anonymous=True) 
     rate = rospy.Rate(30)
     bridge = CvBridge()
     Video = cv2.VideoCapture(0)
     while not rospy.is_shutdown():
         ret, img = Video.read()
         cv2.imshow("talker", img)
         cv2.waitKey(3)
         pub.publish(bridge.cv2_to_imgmsg(img, "bgr8"))
         rate.sleep()

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

编写listener.py:

这个文件订阅talker的话题并获取图像。

#!/usr/bin/env python
import rospy
from sensor_msgs.msg import Image
import cv2
from cv_bridge import CvBridge

def callback(imgmsg):
    bridge = CvBridge()
    img = bridge.imgmsg_to_cv2(imgmsg, "bgr8")
    cv2.imshow("listener", img)
    cv2.waitKey(3)

def listener():

    # In ROS, nodes are uniquely named. If two nodes with the same
    # node are launched, the previous one is kicked off. The
    # anonymous=True flag means that rospy will choose a unique
    # name for our 'listener' node so that multiple listeners can
    # run simultaneously.
    rospy.init_node('listener', anonymous=True)
    rospy.Subscriber("/tutorial/image", Image, callback)
    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()
if __name__ == '__main__':
    listener()

打开三个终端运行roscore，以上两个py文件就可以调用摄像头发布的image信息