Unable to point cloud visualize in RVIZ

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Hello All, I very new to ROS, I am using pcl in ROS. And I am trying to render sample point cloud in the RVIZ. But i am unable to render it due to some issues. A program executing successfully, but in RVIZ point cloud not rendering.

In Displays Tab: (Settings) Fixed Frame : map Global Status: Warn Fixed Frame: No tf data. Actual error: Fixed Frame [map] does not exist Point cloud: Status: OK Topic: /point_cloud

#include <ros/ros.h>
#include <sensor_msgs/PointCloud.h>
#include <string>
#include <random>
 void getRandomPointCloud(sensor_msgs::PointCloud& pc,double centerX, double centerY, int& sizeOfCloud) {
  std::random_device rd;
  std::mt19937 gen(rd());
  std::normal_distribution<> distX(centerX, 2.);
  std::normal_distribution<> distY(centerY, 2.);
  for (int i = 0; i < pc.points.size(); i++) {
        double xValue = distX(gen);
        double yValue = distY(gen);
        pc.points[i].x = xValue;
        pc.points[i].y = yValue;
        pc.points[i].z =
        std::exp(-((xValue * xValue) + (yValue * yValue)) / 4.);
  }
  sensor_msgs::ChannelFloat32 depth_channel;
  depth_channel.name = "distance";
  for (int i = 0; i < pc.points.size(); i++) {
    depth_channel.values.push_back(pc.points[i].z); // or set to a random value if you like
  }
 // add channel to point cloud
  pc.channels.push_back(depth_channel);
}  
int main(int argc, char** argv) {
  ros::init(argc, argv, "point_cloud_test");
  auto nh = ros::NodeHandle();    
  int sizeOfCloud = 100000;
  sensor_msgs::PointCloud keypoints;
  keypoints.points.resize(sizeOfCloud);
  getRandomPointCloud(keypoints, 0.5, 0.5, sizeOfCloud);

  keypoints.header.frame_id = "base_link";
  keypoints.header.stamp = ros::Time::now();

  auto keypoints_publisher =

      nh.advertise<sensor_msgs::PointCloud>("point_cloud", 10);
  ros::Rate rate(30);
  while (ros::ok()) {
    keypoints.header.stamp = ros::Time::now();
    keypoints_publisher.publish(keypoints);
    ros::spinOnce();
    rate.sleep();
  } 
  return 0;
}

It would be a great help for me if you anyone give some suggestions to fix this.