I did the vslam tutorial but I don't know what's happening:

1. The camera pose track is not as accurate as the screenshot on the
tutorial page(Screenshot-1.png).
2. There are no blue lines(Screenshot-2.png).
3. Rviz suddenly quits saying:
        /opt/ros/cturtle/ros/bin/rosrun: line 35:  3274 Segmentation
fault      $exepath "$@"
   The rosbag window actually says Done. Somewhere at Screenshot-2.png is
the end.
4. Is it normally slow?


I tested it with a live stereo camera and had the following:

1. The vslam node suddenly dies after some time:
        [stereo_vslam_node-1] process has died [pid 4290, exit code 1].
     log files:
/home/roboteknik/.ros/log/bdfb27d4-2da9-11e0-b4da-00012e2bb8e1/stereo_vslam_node-1*.log
2. Is it normally slow (<0.4Hz)?