POTENTIAL OF SPOT5 AND LANSAT7 FOR FOREST MAPPING AND

(REDUCTION) HALFEQUATIONS STANDARD POTENTIAL E° (VOLTS) LI+(AQ) + E
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11 PREVALENCE OF POTENTIAL DRUGDRUG INTERACTIONS AND ITS ASSOCIATED
15A NCAC 13C 0202 GROUNDWATER MIGRATION (A) THE POTENTIAL
17 CAN REGIONAL POLICY AFFECT FIRMS INNOVATION POTENTIAL IN

Potential of SPOT5 and Lansat7 for forest mapping and change detection in northwest of Iran

Potential of SPOT5 and Lansat7 for forest mapping and change detection in northwest of Iran



Ali Darvishsefat

University of Tehran

[email protected]



The main objectives of this study are evaluation of the potential of the Landsat7 ETM+ and SPOT5 images in forest mapping, updating the forest map at the scale of 1:25000, change detection of the forest area in between 1994 and 2001. The study area is 1950 and covering 13 standard sheets of 1:25000. in northwest of Iran. The simultaneous Landsat7 and SPOT5 images dated July and August 2001 were analyzed.


The investigation on the image quality showed that there were no important radiometric and geometric distortions. Orthorectification of satellite data was implemented using ephemeris data and a digital elevation model. The geocoded image was checked for reliability in comparison with the digital topographic map. Several spectral transformations such as rationing, PCA, Tasseled cap were performed on the satellite data. The multispectral bands were fused with Pan using DIRS method as a radiometric approach. In order to estimate the potential of the satellite data precisely, a ground truth was prepared using aerial photos. In this relation, 38 B&W aerial photos atthe scale of 1:7000 were taken especially for this project. These photos were orthorectified and interpreted.


Image classifications were performed using supervised and a new hybrid approach (digital and visual). At first, the images were classified using maximum likelihood classifier without any knowledge of a-priori possibilities. To get advantage of contextual information and expert knowledge, a forest/non-forest classification was also carried out using visual interpretation at computer display. Based on comparison of the

resulted maps and the ground truth, a better result had been achieved from the hybrid approach, up to 3%. The Landsat7 and SPOT5 data concluded an overall accuracy of 95% and 98 % respectively. It could be concluded that the SPOT5-HRG data is more appropriate than Landsat7 for forest mapping and updating at the scale of 1:25000. Using SPOT5 data, it is possible to map the small forest and non-forest area very accurately. Revision of the orest road is also precisely possible trough spot5 image. Based on the results of the part one of this study, 13 forest maps were updated by hybrid approach using SPOT5 data. The updated forest maps were compared with the forest maps of 1994. This comparison showed that 1738 of the forest area (equal 2.47 % of primary forest area) has been reduced in this period.



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Tags: forest mapping, primary forest, spot5, potential, mapping, lansat7, forest