Calculate area between contour lines on a DEM with Qgis 1.8.0-Lisboa
Based on a DEM of a whole country I have reclassified altitudinal bands with steps of 100 metres (100-200, 200-300...). Then I polygonized the bands in order to get shapefiles and summarized them with the tool „Singleparts to Multiparts“
Now I have one entry in the attribute table for each altitudinal band.
I would like to calculate the area of each band but no matter what I write or select at the field calculator settings, the result is alwasy the same (Even if I change the CRS). And when I save it (finishing the edit mode) the number turns to 0. What am I doing wrong?
I am using qgis 1.8.0.