Area calculation of mapped categories in ArcGIS Desktop?

Question

I have performed supervised classification (Interactive supervised classification and Maximum Likelihood Classification) on landsat reflectance raster data to classify it into seven land use categories.

Now I want to know the area occupied by the mapped categories. Is there a function to do this in ArcGIS 10.1 Basic? The image is projected to UTM WGS 84 projection system. The area should be in sq km or sq m.

Answer 1

There are a couple steps involved as opposed to a single function.

Use the Raster to Polygon conversion tool to convert your classified raster to vector format subset by class (select your land use as the second parameter in the Raster to Polygon tool).

From there you can access the attribute table and use calculate geometry on the area field to derive area in your desired units on a feature by feature basis

To get the total area of a single class, use 'select by attributes' to select the land class features you want to analyze and from the selected features tab, right click the area field and select statistics, the sum will be the total area of your selected land class.

Answer 2

1. Build raster attribute table (if it doesn't already exist)
2. Create new field to store the area
3. Use field calculator to calculate the areas using the "count" field and the cell size of your raster: area = count * cellsize^2

This will be in square meters, assuming that your cell size is in meters. You can divide by 1,000,000 if you'd rather have square kilometers.