Navone, Stella Maris 
  
METHODOLOGY: 
Analysis Of Optical And Radar Images 
The RADARSAT standard mode and Landsat TM images were registered to the study 
area. 
The selected bands were used as input data for the indexes and for deriving the Principal 
components statistics (PCA). 
We tried on the following methods of combining radar with VIS/IR images:. 
* Co-displaying in a viewer The simplest and most frequently used method of 
combining radar with VIS/IR imagery is co-displaying on an RGB color monitor. In this 
technique the radar image is displayed with one (typically the red) gun while the green and 
blue guns display VIS/IR bands or band ratios. This technique follows from no logical model 
and does not truly merge the two data sets. 
* RGB to IHS transforms: RGB (red,green,blue)color composite of bands (or 
band derivatives)such as ratios is transformed into intensity,hue,saturation color space. 
The intensity component is replaced by the radar imageThis technique integrally merges 
the two data types. 
* Principal componentes transform :A similar image merge involves utilizing 
the principal components (PC)transformation of the VIS/IR image.. These are converted to 
a series of principal components. The first principal component, PC-1,is generally accepted 
to correlate with overall scene brightness. This value is replaced by the radar image and 
the reverse transform is applied. 
* Multiplicative :A final method to consider is the multiplicative technique. This 
requires several chromatic components and a multiplicative component which is radar data. 
Assigned to the image intensity. In practice,the chromatic components are usually band 
ratios or PCs’ the radar image is input multiplicatively as intensity (Holcomb 1993). 
The two sensor merge models using transforms to integrate the two data sets (Principal 
Components and RGB to IHS) are based on the assumption that the radar intensity that the 
transform derives from the data inputs. 
A simple approach was used to correlate radar backscatter values with real ground 
feature types.This involved working from the ground to the image. 
The visual and statistical analysis of the enhaced products were made on the basis of 
the ground truth, on a existing semi-detailed map.(Navone et al,1997). . For that purpose the 
maps originated from the different products has been overlapped with the map units obtained 
with the field survey. 
An statistical analysis has been done to determine the accuracy level. The better 
enhaced images were choosen to make a correlation analysis. 
Collection and analysis of field data: 
In desertification research socioeconomics and biophisics aspects should be integrated. 
(FAO, PNUMA, Secretariat for Natural Resources and Human Environment, 1995.) In 
desertification research ,human and biophisics aspects should be integrated. (FAO, PNUMA, 
Secretariat for Natural Resources and Human Environment, 1995.) 
The following processes involved in the biophisical area were studied: 
a)Vegetation cover ( Mueller, Dombois, 1965) 
b) Water erosion (Wischmeir y Smith, 1978) González del Tanago(1991)y Vich(1985). 
c) Wind erosion (Woodruff y Sidoway, 1965) 
d) Salinitation(FAO, 1984) 
Animal pressure and human pressure were estimated to evaluate socioeconomic area. 
FAO(1984) 
Vegetation cover ;water and wind erosion ;salinization;animal pressure and human 
pressure were measure in the field through observations and transects aplying FAO (1984) 
methodology within sample areas This methodology was employed too for the status of each 
one of the desertification processes with some adjustments for the application in this region. 
For mapping precision selected points in the field were measured with GPS. 
Results and Discussion: 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 
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