Error code	Description
Moving too fast	The translation is too far, so the KP matching in SURF may be unreliable
Lost	No reliable translation can be obtained: the causes cannot be further distinguished by the machine but should be noticeable to the users, such as moving so fast that there is little overlapping between the current pair of FOVs or the camera is out of focus
Touching a boundary	There are few KPs detected, so the FoV is likely near a boundary
No error	The translation is reliable