[R-sig-Geo] contour data

[John Callahan]

I have a DEM (2 meter spacing, IMG file format) and I'd like to create 
contour vector data output, shapefiles would be great.  I just 
downloaded R 2.9.0.  Looking for more info, I keep finding references to 
the contour function in the grahics package, but that seems like it only 
produces plots instead of output vectors. 

I know the sp and spatstat packages are good for various types of 
geospatial analysis.  Is one of these 'the next generation' of the 
other?  Would you recommend one or the other specifically for contour 
generation from a DEM?   (My platform is Windows.)  Thanks.

- John


PS - At first pass, I'm going to give gdal_contour 
(http://www.gdal.org/gdal_contour.html) a try.  I'd really like to see 
how this compares with some method within R.

I'm also looking at SAGA for the R interface options.  I just installed 
the most recent QGIS with the ManageR plugin to see what tools that 
brings in.  And GRASS is always an option (either through QGIS or 
standalone) but I don't quite understand how mapsets work yet. 

**************************************************
John Callahan
Geospatial Application Developer
Delaware Geological Survey, University of Delaware
227 Academy St, Newark DE 19716-7501
Tel: (302) 831-3584  
Email: john.callahan at udel.edu
http://www.dgs.udel.edu