Visual methods and systems are described for detecting 
alertness and vigilance of persons under conditions of fatigue, lack of sleep, and 
exposure to mind altering substances such as 
alcohol and drugs. In particular, the intention can have particular applications for 
truck drivers, 
bus drivers, 
train operators, pilots and 
watercraft controllers and stationary 
heavy equipment operators, and students and employees during either 
daytime or nighttime conditions. The invention robustly tracks a person's head and facial features with a single on-board camera with a 
fully automatic system, that can initialize automatically, and can reinitialize when it need's to and provide outputs in realtime. The 
system can classify rotation in all viewing direction, detects' eye / mouth 
occlusion, detects' 
eye blinking, and recovers the 3D(three dimensional) 
gaze of the eyes. In addition, the 
system is able to track both through 
occlusion like 
eye blinking and also through 
occlusion like rotation. Outputs can be visual and sound alarms to the driver directly. Additional outputs can slow down the vehicle cause and / or cause the vehicle to come to a full stop. Further outputs can send data on driver, operator, student and employee vigilance to remote locales as needed for alarms and initiating other actions.