Résumé
Aerial survey is a method of collecting geomatics or other ry by using airplanes, helicopters, UAVs, balloons or other aerial methods. Typical types of data collected include aerial photography, Lidar, remote sensing (using various visible and invisible bands of the electromagnetic spectrum, such as infrared, gamma, or ultraviolet) and also geophysical data (such as aeromagnetic surveys and gravity. It can also refer to the chart or map made by analysing a region from the air. Aerial survey should be distinguished from technologies because of its better resolution, quality and atmospheric conditions (which can negatively impact and obscure satellite observation). Today, aerial survey is sometimes recognized as a synonym for aerophotogrammetry, part of photogrammetry where the camera is placed in the air. Measurements on aerial images are provided by photogrammetric technologies and methods. Aerial surveys can provide information on many things not visible from the ground. exposure station or air station the position of the optical center of the camera at the moment of exposure. flying height the elevation of the exposure station above the datum (usually mean sea level). altitude the vertical distance of the aircraft above the Earth's surface. tilt the angle between the aerial camera and the horizontal axis perpendicular to the line of flight. tip the angle between the aerial camera and the line of flight. principal point the point of intersection of the optical axis of the aerial camera with the photographical plane. isocentre the point on the aerial photograph in which the bisector of the angle of tilt meets the photograph. nadir point the image of the nadir, i.e. the point on the aerial photograph where a plumbline dropped from the front nodal point pierces the photograph. scale ratio of the focal length of the camera objective and the distance of the exposure station from the ground. azimuth the clockwise horizontal angle measured about the ground nadir point from the ground survey North meridian in the plane of photograph.
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