jetson nano用python编写图像发布、订阅话题（四）编写图像发布、订阅的python脚本

编写图像发布、订阅的python脚本

1. talker.py

#!/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

2. listener.py

#!/usr/bin/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()

3.运行

• 启动roscore
• 运行 talker.py

python3 talker.py

这时，我们会发现如下错误

这个错误是因为ros 自带的 cv_bridge 默认是使用python2环境的，所以我们需要使用python3重新编译这个cv_bridge，具体可以参考我的下一篇博客。

jetson nano用python编写图像发布、订阅话题（五）解决cv_bridge与python版本不兼容的问题