tailieunhanh - ASSESSING the ACCURACY of REMOTELY SENSED DATA - CHAPTER 2

Lịch sử của viễn thám là một tương đối ngắn. Chụp ảnh trên không đã được sử dụng như một công cụ lập bản đồ hiệu quả chỉ hơn nửa thế kỷ. Máy quét hình ảnh kỹ thuật số và máy ảnh trên vệ tinh và máy bay có ngay cả một lịch sử ngắn hơn bao trùm hơn 2 thập kỷ. Tuy nhiên, nó là sự phát triển của các thiết bị kỹ thuật số mà có ảnh hưởng sâu sắc nhất về đánh giá độ chính xác cho tất cả các dữ liệu viễn thám. . | CHAPTER 2 Overview The history of remote sensing is a relatively short one. Aerial photography has been used as a mapping tool effectively for just over half a century. Digital image scanners and cameras on satellites and airplanes have even a shorter history spanning a little over 2 decades. However it was the development of these digital devices that had the most profound impact on accuracy assessment for all remotely sensed data. AERIAL PHOTOGRAPHY The first aerial photograph was acquired from a balloon in 1858 but it wasn t until 1909 that Wilbur Wright took the first aerial photograph from an airplane. Even then the extensive use of aerial photography for mapping and interpreting land use and land cover didn t begin until after World War II Spurr 1948 . In these early days the focus was primarily on the development of new cameras and other instruments to make the best use of the aerial photographs. Spurr in his excellent book entitled Aerial Photographs in Forestry 1948 presents the prevailing opinion about assessing the accuracy of photo interpretation. He states Once the map has been prepared from the photographs it must be checked on the ground. If preliminary reconnaissance has been carried out and a map prepared carefully from good quality photographs ground checking may be confined to those stands whose classification could not be agreed upon in the office and to those stands passed through en route to these doubtful stands. In other words a qualitative visual check to see if the map looks right has traditionally been recommended. Finally in the 1950s some researchers saw the need for quantitative assessment of photo interpretation in order to promote their discipline as a science Sammi 1950 Katz 1952 Young 1955 Colwell 1955 . In a panel discussion entitled Reliability of Measured Values held at the 18th Annual Meeting of the American Society of Photogrammetry Mr. Amrom Katz 1952 the panel chair made a very compelling plea for the use of statistics in .