On 06/04/09 21:27, Patton, Eric wrote: > I'll post here before checking on the GMT list; hopefully I can get some answers from a GRASS/GMT guru... I can't help you on your precise questions, but have you seen Dylan's article: http://casoilresource.lawr.ucdavis.edu/drupal/node/561 (see link to pdf on that page) ? Moritz