I'm using the same drivers and I experience the same phenomena with the HDL-32. However, if you save the point cloud, e.g. with...
$ rosrun pcl_ros pointcloud_to_pcd input:=/velodyne_points
...you should see that the full point cloud without the shadow. In addition, if you record the data and then play it back with rosbag
, you shouldn't see the shadow but you may still see a "ripple" effect that rotates around the cloud in the same way.
I think that the problem is related to how RViz displays or refreshes point clouds in it's visual display. As far as I can tell it doesn't seem to adversely affect the point cloud in any way.
It might be useful if you could post a bag file.
oh thx but how to upload bag file?
Upload it to something like Google Drive or Dropbox, then post a link here