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3. METHODOLOGY 
Concerning to the scope of project (crop hect- 
garage estimation / cultivation mapping), the 
procedure could be explained in three stages as 
below: 
- Satellite data processing / classification. 
- Rice cultivation mapping. 
- Ground samples checking using GPS. 
3.1 Satellite data processing 
31.1 Since the TM images used in the project 
werc raw data, using 1:50,000 scale topomaps 
and collection of sufficient GCP(s), the TM 
images were geometricsally corrected and the 8 
quarter scenes were mosaicked. 
3.1.2 Using 1:50,000 scale administrative maps 
the boundary of Gilan province was transfered to 
the previously corrected images and the surr- 
ounding part was ommited. 
3.1.3 Concerning to the noticeable forest area in 
the mentioned province and no rice cultivation 
activities in this part, the forest area was ommited 
from the data file to decrease the disk space and 
computing time. 
3.1.4 Concerning to the reed-beds and scattered 
small group of trees within the agricultural areas, 
a primary unsupervised classification was 
performed on the TM data to define the whole 
agriculture area that mainly comprise the rice 
cultivation. 
3.1.5 The obtained results of former stage were 
ground checked and the proper parts were 
selected to be used as training sites for further 
classifications. 
3.1.6 Using the data obtained from unsupervised 
classification and the areas defined as training 
Sites, a supervised classification was performed 
on the raw TM bands and spectral separability of 
ice against the other crops/vegetation was 
evaluated. 
31.7 To raise the spectral separability of rice 
against the other vegetation, different data mani- 
Pulation inclusive of Spectral Ratio, Principal 
461 
Component Analvsis, filtering and the like were 
applied and the best data combination (two PCA 
and three TM bands) with the maximum spectral 
separability was selected. 
3.1.8 Using the results of the former stage, the 
final supervised classification was done and the 
three different kinds of rice eventually were 
united as total rice class in the Gilan province. At 
the end of this stage the total area of 193557 
hectars was defined as rice hecterage. 
It 1s mentioned that, regarding to the relative con- 
fusion matrix, an accuracy of 94% was resulted 
for the above rice hecterage. 
3.2 Rice cultivation mapping 
As explained before, Gilan province is divided 
into 11 townships and the total rice production 
Obtain from these townships. Therefore, after 
completion of the mentioned project, using GIS 
facilities, 1:100,000 scale rice cultivation maps 
relative to the different townships with 30 by 30 
minutes of geographic coordinates were 
produced. 
Since the rice distribution was concerned as main 
class to be depicted, on the produced maps, the 
other vegetation is shown as "others". The 
mentioned maps not only are being used for 
agricultural planning / crop monitoring but would 
be concerned as an important part of information 
needed for agricultural database of Gilan. 
3.3 Ground samples checking using GPS 
The TM digital data applied in the project were 
not the real time data. Therefore, to assess the 
accuracy of obtained results the following 
manner was applied: 
3.3.1 Randomly selection of 5x5 pixel windows 
(Ground samples) on the classified images and 
extraction of centre coordinates of the windows. 
3.3.2 In this stage, the constant geodethic 
points(Bench mark) installed by Ntional Carto- 
graphic Centre of Iran and by differential 
positioning method, the ground samples were 
correctly located and percentage of various types 
within the samples were assessed. At the end of 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996