I have been working with some rasters and would like to know how to calculate the area occupied by one element of a raster in QGIS?
I'm assuming you just need to know the area occupied by each value. You can get this value by getting the statistics per value for the raster. Specifically, you want the total number of cells with a particular value. Once you have those totals, you can just multiply them with the cell size of your raster to get the area.
The method of Vectorization gives a cluster based measure of the area rather than a pixel based area. If you were to calculate a specified area or the area of a feature this works just fine. While running the Raster to Vector option ,it identifies the adjacent pixels and groups it and then creates a vector of it. The total count in the image could be confusing here. These methods could also be helpful for calculating the area. What are the methods for calculating area from a raster in QGIS