I'm writing a small ogr/gdal script to get the area of census blocks:
in_file = data/zips/tabblock2010_01_pophu.zip ds = ogr.Open(input_file) lyr = ds.GetLayerByIndex(0) lyr.ResetReading() for feat in lyr: geom = feat.GetGeometryRef() print geom.GetArea()
This gives me numbers like
0.0003370560154999829 for block
010310106002015. Is this an area in meaningful units? If so, which ones? Alternatively, is it something that doesn't make sense like area in lat-long space, where I need to do some kind of projection before I can get the area in real distance units?
EDIT: If I call
DumpReadable() I get:
POLYGON ((-86.121456 31.303452,-86.121207 31.304302,-86.120986 31.305055, ...
so it does look like this is in lat/long units, and so probably gives me area in lat-long space. How do I get real area?