生成cartographer landmark代码

以下是一个简单的cartographer landmark生成代码示例：

#!/usr/bin/env python

import rospy
import tf
from cartographer_ros_msgs.msg import LandmarkList, LandmarkEntry

if __name__ == '__main__':
    rospy.init_node('cartographer_landmark_publisher')

    landmark_list_pub = rospy.Publisher('/landmark_list', LandmarkList, queue_size=10)

    listener = tf.TransformListener()

    while not rospy.is_shutdown():
        try:
            (trans, rot) = listener.lookupTransform('/map', '/landmark', rospy.Time(0))
        except (tf.LookupException, tf.ConnectivityException, tf.ExtrapolationException):
            continue

        landmark_list = LandmarkList()
        landmark_entry = LandmarkEntry()
        landmark_entry.id = 'my_landmark'
        landmark_entry.tracking_from_landmark_transform.translation.x = trans[0]
        landmark_entry.tracking_from_landmark_transform.translation.y = trans[1]
        landmark_entry.tracking_from_landmark_transform.translation.z = trans[2]
        landmark_entry.tracking_from_landmark_transform.rotation.x = rot[0]
        landmark_entry.tracking_from_landmark_transform.rotation.y = rot[1]
        landmark_entry.tracking_from_landmark_transform.rotation.z = rot[2]
        landmark_entry.tracking_from_landmark_transform.rotation.w = rot[3]
        landmark_list.landmarks.append(landmark_entry)

        landmark_list_pub.publish(landmark_list)

        rospy.sleep(0.5)

这个例子假设你已经在地图上放置了一个landmark，并且已经将其命名为“landmark”。它将在每秒钟发布一个包含一个名为“my_landmark”的地标的消息。在Cartographer中，你可以使用这个地标来定位机器人的位置。