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Spatial Analysis Lab (SAL) |
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Creating a Subset of a Larger ERDAS Imagine File (David Wallin, 12/13/06)
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Introduction: A typical Landsat scene covers an area of about 185km by 185km. At times, it makes sense to cut out a subset of this larger image to simplify your analysis and focus on the portion of the scene that is of primary interest. This is quite easy.
Proceedure: Start ERDAS Imagine. It takes several minutes for the software to start up. Be patient. Initially, the Select Viewer Type dialog box will open up. Select the Classic Viewer and click OK. In the Viewer window, go to File-Open-Raster layer and select the image that you want to subset. You may need to use the zoom tools to see the whole image and then zoom in on the portion of the image that you want to subset out. As you move the cursor around the image, the map coordinates of your cursor will display in the lower left of the viewer window. Record the map coordinates of the upper left and lower right of your desired subset.
In the Viewer window, go to Utility-Layer Info to see how many bands are in the image and decide which bands you want to include in your subset.
From the main ERDAS Imagine toolbar, Select Data Prep-Subset Image
From the Subset dialog box, select an input file and an output destination and filename. Specify the map coordinates of the upper left and lower right corners of your subset. Under Data Type, you will probably go with the defaults. This will maintain the format of the original file. Under Output Options, select the bands you want to include in your output file. Finally, push the OK button to perform the subset operation.
When the job is done, push the OK button and your subset is ready to go.
Created by: D. Wallin
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