visp_auto_tracker erro

edit

while i am trying to bring up the visp_auto_tracker, i get an erro and a warn like bwlow ):

[usb_cam-3] process has died [pid 8187, exit code 1, cmd /home/ros/catkin_ws/devel/lib/usb_cam/usb_cam_node __name:=usb_cam __log:=/home/ros/.ros/log/979ed9de-a494-11e5-91e2-000c2928b3ac/usb_cam-3.log]. log file: /home/ros/.ros/log/979ed9de-a494-11e5-91e2-000c2928b3ac/usb_cam-3*.log

i enter into the /home/ros/.ros/log/a3e32604-a490-11e5-acae-000c2928b3ac folder, but i can not see usb_cam-3.log. and i have tried to chmod the log folder,but nothing changes.

what can i do? beg for help.