| 摘要 |
Under the present invention, a warning unit having a light source (e.g., a laser) is mounted on an emergency vehicle. The light source first emits a low intensity light beam (e.g., an infrared light beam) to scan an area in front of the emergency vehicle. The scan is used to detect one or more objects having a height to width ratio exceeding a predetermined threshold. Specifically, the scan is used to detect one or more tall, narrow objects such as poles, sign posts, etc., while ignoring other objects such as people, animals, etc. Once any applicable objects are detected, a second, higher intensity light beam is emitted to illuminate the detected objects with a predetermined indicia. The predetermined indicia can be observed by other motorists and indicates to them a direction of origin of the emergency vehicle.
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