I have a (1) polygon/shapefile of administrative boundaries
and a (2) a raster with different categories (e.g. 1, 2, 3, 4, 5,)
I would like to determine the area of the raster (only category 1) within the polygon/shapefile .
I have tried converting the polygon/shapefile into a raster (feature to raster too, with similar pixel/grid sizes) and combining the 2 rasters. I then estimated the area by looking at the resulting attribute table.
However, I'm not too sure if this is an appropriate way to do this.
Thus, is there a more appropriate/easier method?
Dear Angelo,
your idea is good, but maybe it works better in the other way.
You can use "raster to polygon" to convert the (2) class 1 raster, then "clip" this polygon with the aministrative boundaries and in the end calculate the final area.
Dear Angelo,
with the shapefile already converted to raster, you can calculate a contingency table, e.g. using TabulateArea() in ArcGIS or crosstab() in R. This should return the area of each class within each (rasterized) polygon of your shapefile. Have a look at
http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/tabulate-area.htm
or
https://www.rdocumentation.org/packages/raster/versions/2.6-7/topics/crosstab
for details...
Best regards
Dear Angelo,
In addition to raster::crosstab() function that Sebastian suggested, one another solution in R is the following:
1) Use raster::mask(x, mask) for clipping the raster with the polygon.
2) Subset the raster: r2
Thank you very much for your replies.
I will try all your suggestions.
(Also, thank you for mentioning to be careful with the projection Ákos Bede-Fazekas )
Why not just clip the raster with the .shp file; then use the Count field x area of 1 cell to calculate the area of Class 1?
- Badges
- Science topic
- Similar topics
- Geoscience
- Remote Sensing