tailieunhanh - ENCYCLOPEDIA OF ENVIRONMENTAL SCIENCE AND ENGINEERING - REMOTE SENSING

Viễn thám là hành động thu thập thông tin về một đối tượng từ khoảng cách một. Các ứng dụng môi trường của các cảm biến từ xa thường liên quan đến bộ sưu tập các hình ảnh chụp ảnh hoặc điện tử của bề mặt của Trái Đất hoặc bầu khí quyển từ các nền tảng không khí hoặc spaceborne. Visual giải thích hoặc xử lý máy tính sau đó có thể được sử dụng để phân tích những hình ảnh này. Lịch sử của cảm biến từ xa ngày trở lại thế kỷ 19, khi các bức ảnh. | REMOTE SENSING Remote sensing is the act of acquiring information about an object from a distance. Environmental applications of remote sensing typically involve the collection of photographic or electronic images of the Earth s surface or atmosphere from airborne or spaceborne platforms. Visual interpretation or computer processing can then be used to analyze these images. The history of remote sensing dates back to the 19 th century when the first aerial photographs were taken from balloons and kites. The invention of the airplane provided a better platform and aerial photography advanced rapidly after World War I. With the dawn of the Space Age in 1957 the field of photographic remote sensing expanded to include pictures taken from satellites and other space platforms as demonstrated by pictures taken with a variety of camera types during the Apollo missions. At the same time non-photographic remote sensing systems such as electronic multispectral scanners MSS were developed for use on airborne platforms as well as on meteorological satellites Earth resources satellites and other spaceborne platforms. The 1990s have seen a further expansion of the field of remote sensing with the appearance of new imaging radar satellites imaging spectrometers and high-resolution MSS systems and with the improvement of methods for computer processing of remotely-sensed data. TYPES OF REMOTE SENSING SYSTEMS Several types of remote sensing systems can be differentiated based on the principles employed for measuring electromagnetic radiation. The most common types fall into four broad categories photographic systems videographic systems multispectral scanners and imaging radar systems. Within these categories particular instruments are designed to operate in specific portions of the electromagnetic spectrum. The Earth s atmosphere scatters and absorbs many wavelengths of electromagnetic radiation limiting the portion of the spectrum that can be used for remote sensing. Photographic