opencv - ROS Melodic & OpenCV - CompressedImage 不发布

Question

我是 ROS 新手。我正在玩集成 OpenCV 和 ROS。我正在使用的代码的灵感来自关于将 ROS 消息转换为 CV::mat 并返回的 ROS 教程。

我正在订阅 raspicam 节点发布的主题 /raspicam_node/image/compressed。我没有问题获取主题，将其转换为 CV:mat，并使用 OpenCV 对其进行修改。第 32 行打开一个窗口并显示修改后的 CV:mat 图像。

我的问题出现在第 36 行。我可以使用 rostopic list 查看主题，但是当我 echo 时，它什么也没有出现。如果我使用 rqt_image_view 也是一样。

对我缺少的东西有什么想法吗？谢谢你!

#!/usr/bin/env python

from __future__ import print_function

import roslib
roslib.load_manifest('comp_vision')
import sys
import rospy
import cv2
from std_msgs.msg import String
from sensor_msgs.msg import Image, CompressedImage
from cv_bridge import CvBridge, CvBridgeError


class ImageConverter:

    def __init__(self):
        self.image_pub = rospy.Publisher("modified_image", CompressedImage, queue_size=10)
        self.brige = CvBridge()
        self.image_sub = rospy.Subscriber("/raspicam_node/image/compressed", CompressedImage, self.callback)

    def callback(self,data):
        try:
            cv_image = self.brige.compressed_imgmsg_to_cv2(data, "passthrough")
        except CvBridgeError as e:
            print(e)

        (rows, cols, channels) = cv_image.shape
        if cols > 60 and rows > 60:
            cv2.circle(cv_image, (50,50), 10, 255)

        cv2.imshow("Image Window", cv_image)
        cv2.waitKey(3)

        try:
            self.image_pub.publish(self.brige.cv2_to_compressed_imgmsg(cv_image))
        except CvBridgeError as e:
            print(e)


def main(args):
    ic = ImageConverter()
    rospy.init_node("image_converter", anonymous=True)
    try:
        rospy.spin()
    except KeyboardInterrupt:
        print("shutting down")
    cv2.destroyAllWindows()


if __name__ == '__main__':
    main(sys.argv)

Answer 1

如果您检查 rostopic echo/modified_image，您可以看到您的主题已成功发布。

rqt_image_view 如果您调用您发布的主题 modified_image/compressed 将显示它。

来自compressed_image_transport wiki :

publish it on a topic of the form image_raw/compressed. Then any ROS node using image_transport can subscribe to image_raw with transport compressed, just as if image_transport were used on the publisher side