obtain a copy of the global_costmap

edit

Hi all,

I am planning to write my own node in ROS and I need to access the global_costmap which is being published. I have the following piece of code:

int main(int argc, char** argv){

    ros::init(argc,argv,"publish_multiple_goals");
    ros::NodeHandle n;

    tf::TransformListener tf_(ros::Duration(10));

    costmap_ros_ = new costmap_2d::Costmap2DROS("global_costmap", tf_);
    costmap_ros_->start();

    costmap_ = costmap_ros_->getCostmap();

    unsigned int sizeX = costmap_->getSizeInCellsX();
    unsigned int sizeY = costmap_->getSizeInCellsY();

    std::cout << "SX: " << sizeX << " SY: " << sizeY << std::endl;

    return 0;
}

Now the problem is I don't think I am getting the global_costmap because the size getting printed is (200,200) (Its the default I guess). The correct size of the global_costmap is (280,457). Can anyone tell me what is wrong here? Or If there is any other way to obtain a copy of the global_costmap, please let me know. Let me know if you need more information from my side.

Update:
Yeah, I was able to subscribe to /move_base_node/global_costmap/costmap and obtain nav_msgs/OccupancyGrid message but I was wondering how can I have a new Costmap object which is an exact copy of the global_costmap being published my move_base instead of just getting the OccupancyGrid data or how can I create a costmap object once I have this Occupancy Grid data? I would like to have this so that I can use all the costmap functions.

Thanks in advance.
Naman Kumar