4.2. Vector Processing
4.2.1. Creating Cell Vector
This study in its analysis will use cell based vector, as polygons that contains a lot of attributes data where support the
further analysis. This vector cell is based on boundary of study area, with size 90 meters square. This means that there are 3 pixels by 3
pixels of one pixel of Landsat imagery resolution 28.5 or 30 meters squared. The reason of this procedure is referred to SRTM Shuttle
Radar Topographic Mission resolution 90 meter. These cells were created by using ET Edit Tool Vector Grid,
a plug in extension of Arc View 3.3. In its process, the tool just need four input extent point, Xmin, Xmax, Ymin, and Ymax; and XY
spacing or grid resolution 90 meters. The result of the process is a squared shape, which consist of cells.
Polygon VectorCell
Un-scale Vector Map
Figure 4.8. The result of clipping process between boundary polygon of study
area and square shaped of cells.
40
41 The squared shape of cells will be clipped with polygon
boundary of study area. The result will be shown in Figure 4.8. Illustration of the attribute table that accommodate all the
tabular data as the result of extracting binary data 0 and 1; and statistical calculation from each independent variables and is shown
in Appendix II. By using Query builder in ArcView, shapefile as the result of
extracting contour by Global Mapper can query the polygon greater than or equal 250 meters to obtain the area with topography greater
than or equal 250 meter. Polygon that greater than or equal 250 meters is identified as 0 and less than 250 meters as 1. These both
values must be entered inside the whole cells as wide as the study area. Each cell have to be filled by either value 0 or 1.
Joining process to fill each cell, will be easy by using ArcView Extension, Edit Tool 3.5 - Geoprocessing Assign data by
location Spatial Join - Inside. This tool will join the ID of cell correlated by either value 0 or 1 as the attribute source and squared
shape polygon as target, saved as by a name Polygon VectorCell PVC.
The results process are spatial and its attribute, that must be saved into a new shapefile.
4.2.2. Data Extracting of Contour from SRTM Data Image
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