Update System.h

Make clearer that SaveTrajectoryKITTI and SaveTrajectoryTUM do not work for monocular.

include/System.h

@@ -91,17 +91,19 @@ class System
     void Shutdown();
 
     // Save camera trajectory in the TUM RGB-D dataset format.
+    // Only for stereo and RGB-D. This method does not work for monocular.
     // Call first Shutdown()
     // See format details at: http://vision.in.tum.de/data/datasets/rgbd-dataset
     void SaveTrajectoryTUM(const string &filename);
 
     // Save keyframe poses in the TUM RGB-D dataset format.
-    // Use this function in the monocular case.
+    // This method works for all sensor input.
     // Call first Shutdown()
     // See format details at: http://vision.in.tum.de/data/datasets/rgbd-dataset
     void SaveKeyFrameTrajectoryTUM(const string &filename);
 
     // Save camera trajectory in the KITTI dataset format.
+    // Only for stereo and RGB-D. This method does not work for monocular.
     // Call first Shutdown()
     // See format details at: http://www.cvlibs.net/datasets/kitti/eval_odometry.php
     void SaveTrajectoryKITTI(const string &filename);