The study area (1485 km2) is located in the eastern part of the Syrian Desert
between the provinces of Deir al-Zour and Homs. Stretching from Kabbajeb to
Heer Palace. Due to the similarity of topography, vegetation and land cover, 48
samples were
collected one sample each 4 KM in order to predict the content of
the soil of calcium carbonate through satellite images Land Sat ETM7. The
spectral reflections of surface soil samples were recorded at laboratory using
spectroradiometer (FeildSpecPro®). The results of this study showed that the
presence of calcium carbonate at high rates in the soil increases the spectral
reflectivity values, and that the spectral domain TM 1B was the best to predict
the content of calcium carbonate in the soil.
The aim of the research was to clarify the pre-processing steps required for satellite images
before starting to analyze and extract data from them using the ENVI program.
Radiometric and topographic correction applied to the Landsat image 2017, an
d then we
calculated the NDVI index for this image before and after applying pre-processing.
The results showed a difference in the spectral values of the image before and after the
radiometric correction, especially in near infrared band. The reflection values were
recorded in the original image between (40-50) and (300-3500) in the corrected image. The
difference in the reflection values after the topographical correction was also visible on the
near- infrared and infrared bands, especially in the points where shadows of the terrain.
Differences in the values of NDVI for 2017 were observed before and after the application
of pre-processing on the image, especially in points of good and very good vegetation
coverage with high values of the index.
The study concluded that it is important to follow the minimum number of steps required
for preprocessing steps in order to avoid unnecessary steps and recommend well tested,
readily available, and adequately documented data approaches and data products.
