[R-sig-Geo] Methodology to compare crop maps

[Thiago Veloso]

  Dear R-SIG colleagues,

  I am working with crops planted area maps from two distinct sources. One of the maps is based on a maximum NDVI composition, and the other map uses joint information from satellite and census to estimate the planted area.

 Although the sources employ different methodologies to map the area where the crop exists, the results should be comparable.

 After downloading the datasets, I have performed a visual inpection, and they show reasonable agreement. However, I need a more robust comparison method. Could anybody point out a methodology which allows me to show the difference between both maps?

  Here is an example of each one of the maps: http://www.geog.mcgill.ca/landuse/pub/Data/175crops2000/NetCDF/sugarcane_5min.nc.gz (in netcdf) and http://www.dsr.inpe.br/laf/canasat/en/map.html (not available to download directly, but I can get it in shapefile)

 Thanks in advance,

 Thiago Veloso.