Monthly Archives: March 2012

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).

 

Create mobile maps

Outdoor sport or field work, a GPS has become indispensable. But what if you want to use your own maps? If you are using an Android smartphone and one of the map viewers available on android market, this is fairly easy. You’ll need your favorite GIS application (e.g., GRASS or QGIS), Maptiler, and Mobile Atlas Creator (MOBAC). Continue reading

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

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

Another way to import OSM data in your PostGIS database

There are various options to import your data in a PostGIS database. The OSM2postgresql script (for Linux) sets up a PostgreSQL / PostGIS server or database (optional), imports OSM data into it, process those data (including multi-polygons with holes) and proposes a classification. Check out http://wiki.openstreetmap.org/wiki/Osm2postgresql (where you can find links to some alternative solutions too).