The HUD integrates and manages information from other systems and places it in front of the vehicle driver by means of a screen the size of a dollar bill, located just to the left of the rearview mirror. The screen is transparent and does not interfere with normal vision. HUD technology evolved from military technology. Another military technology finding its way into commercial use is a night vision system designed specifically for law enforcement vehicles. Mounted on the vehicle roof, the heat-sensitive infrared camera covers a 180-degree panorama of the surrounding area, picking up energy from people, tire tracks of speeding vehicles, and discarded weapons still giving off heat from contact with human hands. Combining the HUD technology with infrared imaging puts images that were previously impossible to see right in front of the police officer. As a result, police can search darkened alleys, warehouses, and fields for suspects, weapons, or other evidence. The video camera is another important technological advance. By gathering visual evidence of an encounter, it can save time in internal investigations of police brutality and can corroborate testimony. The MDT offers a fast and useful way to coordinate activities and share information and will significantly change radio- dispatched service calls. Another device gaining popularity is the Automatic Vehicle Locator. The Irvine Police Department in California and other police agencies are using some or all of these technologies. Photograph