I have got .tif file for a country and a dbf file which divides the country area into 42 subunit. I want to get the average elevation data for each subunit in meters.
This is relatively easy to do in two steps:
- Convert your dbf into a shp of polygons. To do so, you can use the tool Line to Polygon. This should be enough if lines from dbf are closed.
- SAGA: Raster statistics for polygons. In this tool you you just need to specify the grid (raster) and the polygons (your new shp) where statistics will be calculated. You can choose between several things (mean, sd, count...), in your case just select "mean".
The result is a shp with a new collumn with the raster statistics.