Updates for tf::MessageFilter example in geometry_tutorials

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Hi,

I was trying to work through the tf tutorials, and had some issues when I got to the part about message filters. The tutorial refers to "turtle_tf_sensor.launch" which is not in the package. I am using Fuerte, and it appears that the file is also missing from Groovy. Also, this issue was previously raised, but I cannot see it being fixed.

I have recreated the missing launch file, and a python node that it runs, based on code from Box Turtle.

If you want me to submit a patch somewhere else please advise.

Missing file 1: geometry_tutorials/turtle_tf/launch/turtle_tf_sensor.launch

<launch>
    <include file="$(find turtle_tf)/launch/turtle_tf_demo.launch" />
    <node name="turtle_pose_stamped_publisher" pkg="turtle_tf" type="turtle_tf_message_broadcaster.py" respawn="false" output="screen" /> 
</launch>

Missing file 2: geometry_tutorials/turtle_tf/nodes/turtle_tf_message_broadcaster.py

[Note: this was modified from Box Turtle code to use Point instead of Pose to match the tutorial code]

#!/usr/bin/env python

import roslib
roslib.load_manifest('turtle_tf')
import rospy

import tf
import turtlesim.msg, turtlesim.srv
from geometry_msgs.msg import PointStamped, Point
from std_msgs.msg import Header

class PointPublisher:
    def handle_turtle_pose(self, msg, turtlename):
        self.pub.publish(PointStamped(Header(0, rospy.rostime.get_rostime(), "/world"), Point(msg.x, msg.y, 0)))

    def __init__(self):
        self.turtlename = "turtle3" #rospy.get_param('~turtle')
        self.sub = rospy.Subscriber('/%s/pose' % self.turtlename,
                         turtlesim.msg.Pose,
                         self.handle_turtle_pose,
                         self.turtlename)
        self.pub = rospy.Publisher('turtle_point_stamped', PointStamped)



if __name__ == '__main__':
    rospy.init_node('tf_turtle_stamped_msg_publisher')
    rospy.wait_for_service('spawn')
    spawner = rospy.ServiceProxy('spawn', turtlesim.srv.Spawn)
    spawner(4, 2, 0, 'turtle3')

    pp = PointPublisher()

    pub = rospy.Publisher("turtle3/command_velocity", turtlesim.msg.Velocity)
    while not rospy.is_shutdown():
        pub.publish(turtlesim.msg.Velocity(1,1))
        rospy.sleep(rospy.Duration(0.1))

It would also be great to add to the tutorial that the following lines should be added to CMakeLists.txt (assumes the file with code is named "turtle_msgfilter.cpp").

rosbuild_add_boost_directories()
rosbuild_add_executable(turtle_msgfilter src/turtle_msgfilter.cpp)
rosbuild_link_boost(turtle_msgfilter signals)