Added observers for tracking data

spatz/utils/preprocess.py

@@ -152,6 +152,9 @@ def preprocess_file(path):
     df = compute_omegas(df)
     df = preprocess_rotations(df)
 
+    # Set the altitude to meters
+    df['altitude'] *= 1000
+
     renaming = {
         'sonic_velocity':       'speedofsound',
         'Time':                 'time',