tailieunhanh - ASSESSING the ACCURACY of REMOTELY SENSED DATA - CHAPTER 6

Sau khi kiểm tra ma trận lỗi cho ý nghĩa thống kê, bước tiếp theo trong phân tích liên quan đến việc khám phá lý do tại sao một số các nhãn chính xác bản đồ trang web không phù hợp với nhãn tham chiếu. Trong khi nhiều sự chú ý được đặt trên tỷ lệ phần trăm chính xác tổng thể, đến nay những mối quan tâm phân tích thú vị hơn khi học tập tại sao các trang web không thuộc trên đường chéo của ma trận lỗi. Để sử dụng hiệu quả các bản đồ và lập. | CHAPTER 6 Analysis of Differences in the Error Matrix After testing the error matrix for statistical significance the next step in analysis involves discovering why some of the accuracy map site labels do not match the reference labels. While much attention is placed on overall accuracy percentages by far the more interesting analysis concerns learning why sites do not fall on the diagonal of the error matrix. To both effectively use the map and to make better maps in the future we need to know what causes the differences in the matrix. All differences will be the result of one of four possible sources 1. Errors in the reference data 2. Sensitivity of the classification scheme to observer variability 3. Inappropriateness of the remote sensing technology for mapping a specific land cover class and 4. Mapping error. This chapter reviews each one of these sources and discusses the impacts of each one to accuracy assessment results. ERRORS IN THE REFERENCE DATA A major assumption of the error matrix is that the label from the reference information represents the true label of the site and that all differences between the remotely sensed map classification and the reference data are due to classification and or delineation error. Unfortunately error matrices can be inadequate indicators of map error because they are often confused by errors in the reference data Congalton and Green 1993 a function of Registration differences between the reference data and the remotely sensed map classification caused by delineation and or digitizing errors. For example if GPS is not used in the field during accuracy assessment it is possible for field 1999 by CRC Press personnel to collect data in the wrong area. Other registration errors can occur when an accuracy assessment site is incorrectly delineated or digitized or when an existing map used for reference data is not precisely registered to the map being assessed. Data entry errors. Data entry errors are common in any database .