Atmospheric and topographic correction of multitemporal Landsat TM imagery
Zhang Yugui
The Research Institute of Forest resource Information
Chinese Academy of Forestry
Abstract
The paper briefly introduced a developing system for comprehensive correction satellite imagery. Standarized reflectance images were produced by atmospheric correction, topographic correction, sensor calibration etc. The atmospheric parameters parameters were interpolated by using local meteorological records. The path radiance derived from visual range is adjusted with dark pixels in the image data. A digital topographic model was used both to correct for the georadiometric effects and to monitor the optical thickness. The normalized reflectance image were enhanced with linear or non-linear transformation. A set of multitemporal subscenes of four dates in Trolleba, Sweden were used as examples to illustrate the good correspondence of correction results in quite different atmospheric conditions.
Introduction
The main factors that seriously affect the radiometric quality of digital satellite data are atmospheric attenuation and topographic distortion, in addition to sensor variation. All these factors are related to and restrictive with each other. Therefore, a correction algorithm that considers only a single digital topographic model. The paper described a developing correction system which made comprehensive correction of Landsat TM and other satellite data, including sensor calibration, path radiance evaluation, the calculation of attenuation coefficients of atmosphere, the variations of direct solar illumination and diffuse illumination caused by topography, as well as minor modifications of the components of optical thickness due to calculate the needed atmospheric parameters by using metrological records, and presented result ofthe calculation after these parameters were input to the radiative transfer model of Turner.
The multitemporal TM images used in this study consist of 4 subscenes of 400 X 400 pixels of the same Trollebo scene, located in south-central part of sweden. The elevation of the area is from 164 to 285 meters ASL. Clear water bodies are scattered over the whole area. The trollebo area contains mainly forest lands with a small portion of agricultural fields. The four dates constitute the whole growing season of forest vegetation , Pine, spruce , birch and broadleaves make up the major forest type categories. Table 1 listed the data of the 4 dates.
Table 1. Parameters for trollebo subscence. The scene center
coordinates, sun elevation azimuth and view angles
are in decimal degrees.
| Scene |
Over pass time |
scene center coordinates |
sun azim |
sun elev |
view angle |
Sun-earth dist. (au) |
| 1 |
194/20:2 1984.4.27 09 35 39 |
(57.317,14.756) |
133.42 |
39.17 |
2.058 |
0.9932 |
| 2 |
194/20:2 1984.5.13 09 36 12 |
(57.819,14.718) |
131.47 |
43.47 |
2.733 |
0.9794 |
| 3 |
193/20 : 1984.7.09 09 27 05 |
(57.317,15.713) |
123.88 |
44.98 |
1.324 |
0.9670 |
| 4 |
193/20:2 1984.9.0209 39 38 |
(57.317,14.493) |
136.92 |
33.66 |
2.987 |
0.9827 |
