I have polygons of countries with its administrative divisions, I would calculate the areas of each division in a country accurately.
I got the bounding boxes for each country, then I divided its width (longitudely) by its height (latitudely).
ratio = 1, the country extends equally South-North as West-East
ratio < 1, it extends West-East
ratio > 1, it extends South-North
But I made my own criteria:
- If the
ratio < 0.7, I used an Albers equal-area projection
+proj=aeawith the 1st SP parallel is
1/6degree below the northernmost latitude of the country, and the 2nd SP is
1/6degree above the southernmost latitude.
- If the
ratio is between 0.7 and 1.3, I used Lambert azimuthal equal area
+proj=laeacentered at the center of the bounding box.
ratio > 1.3, I used transverse cylindrical equal-area
+pro=tceawith central meridian is at the center meridian of the country and
My question Would someone approve it to me, that it lets me get accurate areas relatively better than a projection for the whole continent or the whole world, or isa it boring time taking method?