Sexante toolbox for QGIS

QGIS already has very strong analytical capabilities through its GRASS toolbox. Now, this is further extended by a new plugin that offers direct access to the Sextante toolbox. With this toolbox, QGIS can tap into 300+ functions from SAGA GIS and a number of other functions. Continue reading “Sexante toolbox for QGIS”


How to reduce PDF file size in Linux

I have a scanned report of 181 pages, resulting in a 20MB file. Still OK, unless you need to share the document with a very slow internet connection.

In comes Gostscript, a command line tool that can read and manipulate pdfs. On eHow, you can find a short tutorial how to do this.

Update of GADM datasets

It is always good to keep an eye on your data sources if you don’t want to miss out on new versions. Like the Global Administrative Areas database (GADM), which published version 2 of their data set earlier this year (I thought about revisiting their site after reading this post). A fairly relevant update with updated boundaries for e.g., Sudan.  and with level two administrative boundaries now available for most countries.

The files are available as shapefile, ESRI personal or file geodatase, Google earth .kmz file or R spatial polygon dataframe. If only they would make it available in spatialite format.. (I know, it is easy enough to import shapefiles into a Spatialite database, I am just being lazy).


Add geometry values to vector layer in GRASS GIS

In my previous post I explained how to add geometry values to the attribute table of a vector map in QGIS. You can do the same in GRASS GIS. It is slightly more complicated (don’t worry, it is still easy enough), but also more powerful. Below I will briefly explain how to use this tool using the GUI or command line. Continue reading “Add geometry values to vector layer in GRASS GIS”

Adding geometry columns to attribute table of vector map

What if you have a vector polygon layer and you want to add a column to the attribute table with the size (area) of each individual polygon? Very simple in QGIS, just go to the vector menu: vector | Geometry tools | Export/Add geometry columns, which will give you the following input screen: Continue reading “Adding geometry columns to attribute table of vector map”