Transform coordinates x,y from base_link to odom

edit

Hi guys, my algorithm calculates the position x, y (as double type) of an object scanned by the laser, but the problem is that these coordinates belongs to the base_link frame. Now I have to convert them to the odom reference triad, how can I do it? Do you have any TF code to implement?

Edit: this is what I'm trying to use

  tf::StampedTransform base_link_to_odom_tf;
  tf::TransformListener tfListener_;
  tfListener_.waitForTransform("/odom", "/base_link", ros::Time(0), ros::Duration(0.1));

  try
  {
      tfListener_.lookupTransform("/odom", "/base_link", ros::Time(0), base_link_to_odom_tf);
  } catch (tf::TransformException ex) {}

  tf::Vector3 point, new_pos;
  point.setZ(0.0);
  point.setX(pos_x);
  point.setY(pos_y);
  new_pos = base_link_to_odom_tf * point;

    obj_x.push_back(new_pos.x());
    obj_y.push_back(new_pos.y());
    ...
    obst_markers.markers[i].pose.position.x = obj_x[i];
    obst_markers.markers[i].pose.position.y = obj_y[i];

where obj_x and obj_y are vectors of doubles used to load the objects as marker arrays

Edit2: after some tests moving the object in Gazebo I have these coordinates in output

x: 3.55343  new_pos.x(): 3.17272e-309 
y: -0.375864  new_pos.y(): 2.97874e-309

x: 5.35993  new_pos.x(): 4.41872e-309
y: -0.338986  new_pos.y(): 4.01111e-309

x: 3.71522  new_pos.x(): 3.28127e-309 
y: 1.33082   new_pos.y(): 3.65853e-309