text:  As human analysts using the technique lead to <unk> biases , efforts have been made to make more objective estimates using computer programs , which have been aided by higher @-@ resolution satellite imagery and more powerful computers . Since tropical cyclone satellite patterns can <unk> over time , automated techniques use a six @-@ hour averaging period to lead to more reliable intensity estimates . Development of the objective Dvorak technique began in 1998 , which performed best with tropical cyclones that had eyes ( of hurricane or typhoon strength ) . It still required a manual center placement , keeping some <unk> within the process . By 2004 , an advanced objective Dvorak technique was developed which utilized banding features for systems below hurricane intensity and to <unk> determine the tropical cyclone 's center . A central pressure bias was uncovered in 2004 relating to the slope of the <unk> and cloud top temperatures which change with latitude that helped improve central pressure estimates within the objective technique . 
  