Running on TUM dataset

[CharlieLeee]

@heethesh Hi, thanks for the inspiring work! I would like to know the right way to run your model on the TUM dataset( e.g. walking). The following is how I'm going to try it, and please correct me if I misunderstand:

1. catkin_make orb_slam(I use the one in your repo)
2. segment the pictures converted from the bag (I would appreciate if the steps are offered)
3. run updata_rosbag to apply the semantic segmentation result, since the script requiresimage-dir (I would like to know the specific way to do this step)

Thanks again for the great work, looking forward to your reply.

[heethesh]

Added USAGE.md.