This procedure allows the remote sensing operator to pull out features that are visible on one or more bands, ratios, or principal components in the scene. Use the classification toolbar. Here is a good image for looking at plowed fields, developed land, and water using PC4.
If we look at the histogram for this image, we would likely divide the image into the dark and light areas. We use a simple "if" statement.... IF (PC3< x) then "red" else null. Let's see if we can pull that off in a raster calculator statement.
The upper layer is a "red" layer is on when the criteria is met. We've now captured the dark pixels in the PC4 image. How do we get rid of the water, or plowed fields and keep just the developed land? We need to add an additional criteria, such as
....if (PC4 < x) and (band5 > y) then "red" else null.....
Again, can we get here in raster calculator?
In the classification lab you will isolate just the plowed fields starting with PC3, then further with the use of a ratio or a different PC.
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