I'm having trouble figuring out how to perform SLAM with rtabmap, I am using "roslaunch rtabmapros demorobot_mapping.launch rviz:=true rtabmapviz:=false"(This is the correct command right?) from the wiki.However the image from my camera looks weird, the images come out as black and white,also no point clouds any image from whwre my camera is facing shows up on the rviz, I just see an empty grid map.I dont even see the model of the robot I'm using in rviz either. Maybe I'm using the wrong command?