Why is tf2::doTransform not transforming my pointcloud?

edit

The function tf2::doTransform does not seem to transform my pointcloud. I made a minimal example to showcase my problem or maybe I am misunderstanding something.

In rviz i subscribe to both topics: "/realsense_zr300/points2" and "/world/source", but the two pointclouds lie on each other, why? Shouldn't they be different because the source is in the realsense frame and the transformed cloud is in the world frame? I also checked the data field of the input and output and they are the same, how can this be if I am applying a transform? The transform sets the frame_id of the output correctly to world, but does not change any value in the data. Attached are two pictures to clarify how things look like:

EDIT: the frame id of the input cloud is “realsense_zr300_ir_optical_frame“ and of the output cloud it is “world“. The first few points are exactly the same in both clouds, I am not at the pc currently, but the valued were something similiar to [0,0,~179, ~240, 0,0,~ 179, ~240...] when I echoed the messages and looked at the data field. Thank you for the good edit.

rviz and gazebo

I excpected this transformation to transform the pointcloud onto the floor, or atleast to not be the same as the input cloud. What am I doing wrong?

main.cpp

#include "my_class.h"

int main(int argc, char** argv)
{
  ros::init(argc, argv, "test");
  MyClass mc;
  ros::spin();
  return 0;
}

my_class.h

#ifndef CPP_MY_CLASS_H
#define CPP_MY_CLASS_H

#include <ros/ros.h>
#include <tf2_ros/transform_listener.h>
#include <tf2_sensor_msgs/tf2_sensor_msgs.h>
#include <sensor_msgs/PointCloud2.h>

class MyClass
{
public:
  ros::NodeHandle nh_;
  tf2_ros::Buffer tfBuffer_;
  tf2_ros::TransformListener tfListener_;
  ros::Publisher W_source_pub_;
  ros::Subscriber points_sub_;

  MyClass();
  void point_cloud_cb(const sensor_msgs::PointCloud2::ConstPtr& msg);
};

#endif //CPP_MY_CLASS_H

my_class.cpp

#include "my_class.h"

MyClass::MyClass() : tfListener_(tfBuffer_)
{
  points_sub_ = nh_.subscribe("/realsense_zr300/points2", 1, &MyClass::point_cloud_cb, this);
  W_source_pub_ = nh_.advertise<sensor_msgs::PointCloud2>("/world/source", 10);
}

void MyClass::point_cloud_cb(const sensor_msgs::PointCloud2::ConstPtr& msg) {
  geometry_msgs::TransformStamped C_to_W_transform;
  try {
    C_to_W_transform = tfBuffer_.lookupTransform("world", "realsense_zr300_ir_optical_frame", ros::Time(0));
  }
  catch (tf2::TransformException &ex) {
    ROS_WARN("%s", ex.what());
    ros::Duration(1.0).sleep();
    return;
  }
  sensor_msgs::PointCloud2 w_cloud;
  std::cout << C_to_W_transform.transform.translation.x << std::endl;
  std::cout << C_to_W_transform.transform.translation.y << std::endl;
  std::cout << C_to_W_transform.transform.translation.z << std::endl;
  std::cout << C_to_W_transform.transform.rotation.x << std::endl;
  std::cout << C_to_W_transform.transform.rotation.y << std::endl;
  std::cout << C_to_W_transform.transform.rotation.z << std::endl;
  std::cout << C_to_W_transform.transform.rotation.w << std::endl;
  tf2::doTransform(*msg, w_cloud, C_to_W_transform);
  W_source_pub_.publish(w_cloud);
}

I wrote a gazebo model plugin that publishes the tf tree. To check it is correct I print the values of the transform I get and they are, as they should be:

x: 0 y: -0.5 z: 0.5

x: -0.189251 y: 0.184585 z: 0.690409 w: 0.673385

The update loop of the plugin looks like this:

void ModelTf::OnUpdate() {
    pose_ = this->model->GetWorldPose();
    transformStamped_.header.stamp = ros::Time::now();
    transformStamped_.header.frame_id = "world ...