I am working on differentiating cocoa plants from other vegetation types using 4 epoch bwt 1980-2010. I need to extract the spectral signature for cocoa plants and other known features. I plan using landsat or MODIS imagery. How can I do this using either ArcGIS, Erdas, Envi or Idrisi?
Draw polygons with ArcGIS. The polygons are areas with a specific type of vegetation. You have some areas FROM Landsat 7 and MODIS. You want to "export" the spectral signature of these areas. With ArcGIS you can use "zonal statistics as a table" to extract the mean spectral values for each band and within your polygon. You can run it in batch mode (right click on the tools > batch) to have the values related to each band of each satellite.