Laser -> point cloud, tf drop all packages

edit

hi, all,

I am super new to ROS. I am trying to use tf to transform the laser input to tf base_link frame. But I am constantly getting error msg like "MessageFilter [target=base_link ]: Dropped 100.00% of messages so far. Please turn the [ros.agv.message_notifier] rosconsole logger to DEBUG for more information." and it seems the call back was never invoked. I tested the laser msg by subscribing to the raw msg and it works fine. I think there might be a broken link somewhere in the settings. Can someone help me? here's the code for the listener.

class LaserScanToPointCloud{
public:
  ros::NodeHandle node;
  laser_geometry::LaserProjection projector;
  tf::TransformListener listener;
  message_filters::Subscriber<sensor_msgs::LaserScan> laser_sub;
  tf::MessageFilter<sensor_msgs::LaserScan> laser_notifier;
  ros::Publisher scan_pub;
  LaserScanToPointCloud(ros::NodeHandle n) :
    node(n),
    laser_sub(node, "base_scan", 10),
    laser_notifier(laser_sub,listener, "base_link", 10)
  {
      printf("setting up callback\r\n");
      laser_notifier.registerCallback(boost::bind(&LaserScanToPointCloud::scanCallback, this, _1));
      laser_notifier.setTolerance(ros::Duration(0.01));
      scan_pub = node.advertise<sensor_msgs::PointCloud>("my_cloud",1);
      printf("set up callback\r\n");
  }
  void scanCallback (const sensor_msgs::LaserScan::ConstPtr& scan_in)
  {
    sensor_msgs::PointCloud localcloud;
    printf("%ds:%lfm\r\n",scan_in->header.stamp.sec,scan_in->ranges[128]);
    try
    {
        projector.transformLaserScanToPointCloud("base_link",*scan_in, localcloud,listener);
    }
    catch (tf::TransformException& e)
    {
        std::cout << e.what();
        return;
    }
    printf("(%f,%f,%f)\r\n",localcloud.points.data()->x,localcloud.points.data()->y,localcloud.points.data()->z);
    // Do something with cloud.
    scan_pub.publish(localcloud);
  }
};
int main(int argc, char** argv)
{
  ros::init(argc, argv, "my_scan_to_cloud");
  ros::NodeHandle n;
  LaserScanToPointCloud lstopc(n);
  ros::spin();
  return 0;
}

and here's the broadcaster

int main(int argc, char** argv){
  ros::init(argc, argv, "robot_tf_publisher");
  ros::NodeHandle n;
  ros::Rate r(50);
  tf::TransformBroadcaster broadcaster;
  while(n.ok()){
      broadcaster.sendTransform(
              tf::StampedTransform(
                      tf::Transform(tf::Quaternion(0, 0, 0, 1), tf::Vector3(0.0, 0.0, 0.2)),
                      ros::Time::now(),"base_link", "base_scan"));
      r.sleep();
  }
  return 0;
}

million thanks Ray