The Study of the Correction Model of Daul - direction Scanning Error of TM A DATA Image
Li Shu-kai, Liu Tong
The Institute of Remote Sensing Application
Chinese Academy of Sciences, Beijing, 100101
Abstract
The sensors of TM image are different from MSS on LANDSAT. The MSS data is collected with mono-direction scanning and TM data with daual - direction scan. The sensor of TM is a improved sensor of MSS. Position deviation in scanning direction is produced by the difference of normal and reversal direction scanning of TM sensor. The deviation value is a complicate function of T ( data collection time of satellite ) in which there is some high - frequency elements. The charactertics of TM A DATA image is analysed first in this study. Using direct digital correlation method, the study of correction model of dual-direction scanning error of TM image has been finished primely. Some algorithms and software's are developed. The result is that 2.15 hours is necessary for the processing of correction of dual-direction scanning error with a scence TM A DATA.
Preface
The application of remote sensing image has been developed from the analysis of visual - interpretation and computer classification to a new period, in which compound analysis of multi-remote sensing image is developed with multi-criterion and multi-data resources. Positioning precession is distinctly more and more important. Factual positioning precision of rough correction image is unclear to say, where the relief displacement must be corrected in the complicated terrain area. In the edge of TM image , relief displacement of half pixel is produced by 117 meters height difference and 8.4 pixels by 2000 meters. These problems have to be considered when the compound analysis is done with the multi-remote sensing information and non-remote sensing information. Relief displacement can not be corrected with precise geometric processing of polynomial method. The best geometric precise processing model for relief displacement correction is the collincrity equations of central projection with parameters. The model of collinerity equations with parameters adapt to the original data which had never been corrected and projective relationship is central projection, that is, MSS and TM A DATA. The research of processing of MSS A DATA had already finished. The study of correction with dual-direction scanning error of TM A DATA is significant for precise correction of TM A DATA. The accurate geo-base for compound processing with multi-data resources also is the purpose and significance for the study.
1. The geometric feature analysis of LANDSAT TM A DATA
The sensor of TM image on LANDSAT 4,5 are dual-direction line scanning sensors with a correction equipment of scan - Line behind the prime lens. The function is for forward movement compensation to the dual-direction scanning line. Then each scanning line is designed vertical to the satellite orbital trace ( figure 1). There are 16 scanning - lines for band 1 to band 5 and band 7,4 scanning - line for band 6. The data collection of TM is different from MSS. Image data of TM is collected by west to east scanning ( forward scan) and east to west scanning ( backward scan ) but MSS just with west east. Because of the difference of forward scan and backward scan, the object on ground is successive in the TM A DATA image.
Fig 1 The correction of TM scan-line
In figure 2, there are four scanning band ( 1,2,3,4) that each band is composed of sixty scanning line which is the data of forward or backward scan. A,B, and C is road, lake and river, Image of the road on the even band is not successive with the odd band. After verification, L1 is not equal to L2. The value of L is about 45±10 pixels with statistic result of 200 scanning bands.
Fig 2 Un-successive ground object on TM A DATA
