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This paper analyses the geometric and radiometric accuracy of SPOT HRV-1 data in comparison to Landsat-5 TM imagery, using concurrent TM and SPOT images recorded almost simultaneously over the southern Ardeche region (France), both data sets being available on system corrected CCT. The TM and SPOT scenes can be registered to map projection with sub-pixel accuracy, while a common pixel size of 30 x 30 m is maintained. The mountainous character of the study region requires the use of digital elevation data for the compensation of relief induced distortions. The radiometric comparison of TM and SPOT uses the apparent reflectances of 28 reference targets representing a wide range of vegetated and non-vegetated cover types. Terrain slopes are generally less than 10 percent and considered insignificant. While a very good match of TM and SPOT reflectances in the visible bands can be stated, a considerable discrepancy is found concerning the calibration of the near-infrared channel of the SPOT HRV-1 sensor. A calibration adjustment is performed with reference to the contemporary TM scene, and both scenes are corrected for atmospheric absorption, scattering and pixel adjacency effects. It is demonstrated, that identical values of the normalised difference vegetation index (NDVI) can be obtained from both sensors, once proper calibration data are provided.

Additional information

Authors: HILL J, JRC Ispra Estab. (IT);AIFADOPOULOU D, JRC Ispra Estab. (IT)
Bibliographic Reference: Paper presented: Igarss `89, Vancouver (CN), July 10-14, 1989
Availability: Available from (1) as Paper EN 34804 ORA
Record Number: 198910623 / Last updated on: 1994-12-01
Original language: en
Available languages: en
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