How to visualize /camera/depth/points without using rviz?

edit

Hi,

Following this tutorial in the Use ROS there is a tutorial of how to visualize a point cloud, doing that I execute this commands:

$ roscore
$ rosrun openni_camera openni_node
$ rosrun pcl_ros convert_pointcloud_to_image input:=/camera/depth/points output:=/camera/depth/cloud_image

but i get the following error:

[ERROR] [1336450343.870410678]: Error in converting cloud to image message: No rgb field!!

This doesn't happen when I run this instead of my last line:

$ rosrun pcl_ros convert_pointcloud_to_image input:=/camera/rgb/points output:=/camera/depth/cloud_image

I get no error and I do can visualize my image with:

$ rosrun image_view image_view image:=/camera/rgb/cloud_image

It show this image

I can realize that command only accept point clouds from the rgb camera, but how can I visualize the depth images? (without using rviz)

P.S. I'm using ROS Electric, in Ubuntu 11.04

Thanks!