<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt">This article can also help you: http://fluidbook.geoinformatics.com/GEO-Informatics_8_2011/#/36/<br>Best regards<br>Jose Canalejo<br>http://csgis.de/</div></body></html>