displaying a point cloud in rviz

edit

You should add xyz as fields in the header. I have some MATLAB code for it but it should be straightforward to port it to Python, I hope you won't mind ;)

        f = pc.getFields;
        XField = rosmatlab.message('sensor_msgs/PointField',RTC.node);
        XField.setName('x');
        XField.setDatatype(7);
        XField.setCount(1);
        f.add(XField);
        YField = rosmatlab.message('sensor_msgs/PointField',RTC.node);
        YField.setName('y');
        YField.setDatatype(7);
        YField.setCount(1);
        YField.setOffset(4)
        f.add(YField);
        ZField = rosmatlab.message('sensor_msgs/PointField',RTC.node);
        ZField.setName('z');
        ZField.setDatatype(7);
        ZField.setCount(1);
        ZField.setOffset(8)
        f.add(ZField);

Cheers, Marco

here is a sample code to publish a pointcloud2 with python in ros:

#!/usr/bin/env python
import rospy
import math
import sys

from sensor_msgs.msg import PointCloud2
import std_msgs.msg
import sensor_msgs.point_cloud2 as pcl2

if __name__ == '__main__':
    '''
    Sample code to publish a pcl2 with python
    '''
    rospy.init_node('pcl2_pub_example')
    pcl_pub = rospy.Publisher("/my_pcl_topic", PointCloud2)
    rospy.loginfo("Initializing sample pcl2 publisher node...")
    #give time to roscore to make the connections
    rospy.sleep(1.)
    cloud_points = [[1.0, 1.0, 0.0],[1.0, 2.0, 0.0]]
    #header
    header = std_msgs.msg.Header()
    header.stamp = rospy.Time.now()
    header.frame_id = 'map'
    #create pcl from points
    scaled_polygon_pcl = pcl2.create_cloud_xyz32(header, cloud_points)
    #publish    
    rospy.loginfo("happily publishing sample pointcloud.. !")
    pcl_pub.publish(scaled_polygon_pcl)

1. open rivz

2. set fixed frame as map

3. run a roscore

4. add PointCloud2 topic in rviz and select the topic to listen to /my_pcl_topic

5. Done! you should be able to see two points on 1, 1 and 1, 2

You may have to setup Header properly with proper time stamps. Try to publish the pointcloud continuously with updated time stamps in header.

Also, I would try rostopic echo first to validate you have generated correct message format.