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Mapping
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Semi-automated geometric correction for mosaicing number of satellite data
Koki Iwao, Ryosuke Shibasaki & Masataka TakagiI
Murai-Shibasaki Lab, Institute of industrial Science,
The University of Tokyo
7-22, Roppongi, Minato-ku, Toko 106, JAPAN
Tel . +81-3-3403-6231 EXT.2563
Fax. +81-3-3479-2762
E-mail: iwao@shunji.is.u-tokyo.ac.jp
Abstract :
For continental scale land use/land cover study, generation of mosaic image from a large number of satellite images is indispensable. On board system adjustment is insufficient for making mosaiced image. Usually, we use GCP's (Ground Control Point) for high accuracy geometric correction, it is very labor demanding and difficult to find good GCP points in one scene for image coordinate registration. As such, we need to geometrically correct these satellite images at a stretch. In this paper, we propose a method to identify GCP's and tie-points in an automated manner, and to adjust geometric errors over all images based on the idea of block adjustment used in photogrammetry. With this method, we can improve the efficiency and reduce the total amount of GCPs required.
1.Introduction:
Since the South East Asia is a rapidly growing region the world, land use changes take place very drastically and cause a variety of serious environmental issues. Thus is requires more advanced management schemes of land use and environmental resources. We need information and tools to handle and analyze land cover / use change.
To get a good understanding of the changes that are taking place in the landuse and their effects on the local, regional and global scales, we need to have a complete database of the landuses - both past and present, to help us in analyzing the changes on the time scale. Above all, to adjust geometric errors are most important when we handle such a huge number of satellite data because on-board system adjustment is insufficient for making mosaiced image.
2. Methodology
A djust geometric errors overall images based on the idea of block adjustment It is not always easy to find GCP points clearly in one scene for image coordinate registration and geometric correction using GCP is very labor demanding. Further Traditional Geometric Correction Method can not effect on the surrounding satellite image coordinate that means if you can not find good GCP in one scene, you can not make mosaic image.
Therefore is necessary to correct geometrically of these satellite images automatically at one time. In this paper, we propose a method to identify GCP's and based on the idea of block adjustment used in photogrammetry. With this method, we can improve the efficiency and reduce the total amount of GCPs, required for geometric correction automatically. Process of this system are as follows.
Fig. 1 Flow Chart of Geometric Correction
By comparing traditional method and proposed Method, we can say the merits of this system i.e.
- Less need manual Processing
- No need to check gaps between images
- We can manage less GCP images
3.Evaluation of this system
3.1. Preprocessing:
Here, we used Landsat TM (1989, Jan-May). We used band 4 because this band can easily identify the water from the biomass.
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