#usb_cam.launch <launch> <node name="usb_cam" pkg="usb_cam" type="usb_cam_node" output="screen" > <param name="video_device" value="/dev/video0" /> <param name="image_width" value="640" /> <param name="image_height" value="480" /> <param name="pixel_format" value="yuyv" /> <param name="camera_frame_id" value="usb_cam" /> <param name="io_method" value="mmap"/> </node> </launch>
此时摄像头虽然亮着,但是是没有画面的,需要继续打开一个终端执行下面这个脚本 rosrun robot_vision cv_bridge_test.py 执行rosrun robot_vision cv_bridge_test.py可能遇到如下情况 提示没有执行权限或文件不存在,可此时文件是存在的,所以需要修改添加相关文件的可执行权限 输入如下指令:chmod +x cv_bridge_test.py
class image_converter: def __init__(self): # 创建cv_bridge,声明图像的发布者和订阅者 self.image_pub = rospy.Publisher("cv_bridge_image", Image, queue_size=1) self.bridge = CvBridge() self.image_sub = rospy.Subscriber("/usb_cam/image_raw", Image, self.callback) def callback(self,data): # 使用cv_bridge将ROS的图像数据转换成OpenCV的图像格式 try: cv_image = self.bridge.imgmsg_to_cv2(data, "bgr8") except CvBridgeError as e: print e # 在opencv的显示窗口中绘制一个圆,作为标记 (rows,cols,channels) = cv_image.shape if cols > 60 and rows > 60 : cv2.circle(cv_image, (60, 60), 30, (0,0,255), -1) # 显示Opencv格式的图像 cv2.imshow("Image window", cv_image) cv2.waitKey(3) # 再将opencv格式额数据转换成ros image格式的数据发布 try: self.image_pub.publish(self.bridge.cv2_to_imgmsg(cv_image, "bgr8")) except CvBridgeError as e: print e if __name__ == '__main__': try: # 初始化ros节点 rospy.init_node("cv_bridge_test") # 节点 rospy.loginfo("Starting cv_bridge_test node") image_converter() rospy.spin() except KeyboardInterrupt: print "Shutting down cv_bridge_test node." cv2.destroyAllWindows()bridge.imgmsg_to_cv2 将ROS的图像数据格式转化成Opencv的图像数据格式 转化后调用Opencv的库在原图上画一个圆 cv2.circle(cv_image, (60, 60), 30, (0,0,255), -1) 最后通过发布者将处理过 bridge.cv2_to_imgmsg 接口函数 将Opencv数据图转化为ROS的图像数据格式再发布到系统中,如下可以看到发布者 发布的话题 cv_bridge_image