The necessity of accurate registration and geometric rectification arises due to the presence of a number of distortions (errors) in remote sensing images that occur as a result of variations in platform positions, rotation of earth and relief displacements etc. (see Chap. 2). The behavior of most of these distortions is systematic and, thus, can be easily removed at data acquisition centers. It is also generally expedient to procure systematic-corrected images as these are already geometrically rectified to a map projection system such as the Universal Transverse Mercator (UTM). However, systematic corrections are normally performed on the basis of platform ephemeris data obtained from the header information, which may be relatively inaccurate. Therefore, some distortions may still be present in the systematic-corrected data. This can be illustrated with the help of agency supplied Landsat TM images taken at two different times as shown in Fig. 7.1. The images were systematically corrected and geometrically rectified to UTM at the data acquisition center. It can, however, be seen that the two points (marked by “+”) having the same UTM coordinates in both images are located at different positions indicating the presence of non-systematic registration errors.
Weitere Kapitel dieses Buchs durch Wischen aufrufen
- MI Based Registration of Multi-Sensor and Multi-Temporal Images
Pramod K. Varshney
- Springer Berlin Heidelberg
- Chapter 7
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