Marker display points Overwrite

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I would like to display Marker points with rviz. However I wish to have the points overwrite (persistent) in every iteration and not plot new points in each iteration.

I am plotting a set of 50 points per iteration. I want the points to accumulate, ie. at 2nd iteration I have 100 points on display on 3rd iteration 150 points and so on.

I noticed the documentation link:rviz/DisplayType/Marker have a parameter lifetime. I tried setting it to zero as in the code but still cannot get that effect. How can I achieve it?

#include <ros/ros.h>

#include <visualization_msgs/Marker.h>
#include <geometry_msgs/Point.h>



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

    ros::init(argc, argv, "viz3d");
    ros::NodeHandle nh;


    ros::Publisher pub = nh.advertise<visualization_msgs::Marker>("viz_marker", 100 );
    ros::Rate rate(2);

    cv::Mat frame, dframe;

    ros::Time stamp = ros::Time::now();
    while( ros::ok() )
    {
        ROS_INFO_STREAM( "Publishing point " );

        visualization_msgs::Marker msg;
        msg.header.frame_id = "/my_frame";
        msg.header.stamp = stamp;
        msg.ns = "xuv";
        msg.id = 0;
        msg.action = visualization_msgs::Marker::ADD;
        ros::Duration du(0.0);
        msg.lifetime = du;

        msg.type = visualization_msgs::Marker::POINTS;


        msg.scale.x = 0.02;
        msg.scale.y = 0.02;


        for( int i=0; i<50 ; i++)
        {
            geometry_msgs::Point pt;
            pt.x = drand48();
            pt.y = 10*drand48();
            pt.z = drand48();

            std_msgs::ColorRGBA col;
            col.r = 1.0;
            col.g = 0.0;
            col.b = 0.0;
            col.a = 1.0;
            msg.colors.push_back(col);

            msg.points.push_back(pt);

        }


        msg.color.r = 0.0;
        msg.color.g = 0.0;
        msg.color.b = 0.0;
        msg.color.a = 1.0;

        pub.publish(msg);
        rate.sleep();

    }


}