This function is a convenience wrapper function to extract variable values from a database of geographical layers.
Usage
extract.val(latlon, layers)
Arguments
latlon
latlon is a matrix of two columns for latitude and longitude.
layers
layers is a list of complete layer names. The name is used for display; the value are used for reading the layers.
Value
Returns a matrix of several columns containing the original lat/lon, the converted sequential id based on the grid,
and the extracted values.
Details
See description. The function assumes so far that the layers are in a format readable by readGDAL; all layers must be standardized to the same reference grid and resolution.