Finding open data for the Netherlands

Open data is  becoming increasingly important and there are considerable advantages, such as accountability, cost and time savings for users, easier knowledge sharing and increased efficiency in public services.

The importance of open data is more and more recognized (see e.g., this blog article (in Dutch) and this and this report). However, to bank on such advantages, there is a need to increase awareness about open data and make it easy to find and use the open data.  Continue reading “Finding open data for the Netherlands”

GRASS GIS 7.0.2 released

For those who haven’t seen it yet, GRASS GIS 7.0.2 has been released! See here for the announcement and here for a detailed overview of all the changes (over 190 of stability fixes and improvements since GRASS GIS 7.01).

For those still using GRASS GIS 6.4, GRASS GIS 7 offers a strongly improved interface, a considerable increases in speed and efficiency, support for huge files, and a long list of new modules to analyse raster and vector data, including a full temporal framework. Also important, as a stable release series, 7.0.x enjoys long-term support.

As usual, a great thanks to the developers!

Picture Pile; play and help science

There is a successor of Cropland Capture, Picture Pile, from the people behind Geo-Wiki. Like Cropland Capture, this tool / game uses a citizen science approach, in this case to track deforestation.

The game presents a series of side-by-side images of the same location several years apart and ask you the question whether  “ you see tree loss over time?”. Options are yes, no or maybe.

Perhaps a bit to my surprise, this is fairly addictive and I love the idea behind it. And you can play it on your computer, tablet or phone. If you want to give it a try, go to .

Importance of spatial data accuracy – of protected areas

Geographic information systems (GIS) tool are becoming increasingly important in conservation and natural resource management planning and implementation. The good news is that it is also getting easier to find relevant and freely available (spatial) data sets online. However, we also need to be careful in evaluating the accuracy and reliability of these data sets, as illustrated by an article I came across today. Continue reading “Importance of spatial data accuracy – of protected areas”

GRASS GIS categorical raster layers in QGIS

With the QGIS GRASS plugin, you can easily open a GRASS raster layer in QGIS. One disadvantage, however, is that if your GRASS layer has category labels, these will not show in the QGIS legend. See for example the landuse layer in the North Carolina data set,  opened in QGIS in the screenshot below.


It isn’t too much problem to define the labels in QGIS if you have few categories only, but what if your map in GRASS has many categories, all neatly labelled in GRASS. Sure you don’t want to add those category labels manually again in QGIS?

I don’t, so I wrote a small GRASS GIS addon, r.category.trim, that export the attribute table and colour table in GRASS GIS as a QGIS colour map file.

Continue reading “GRASS GIS categorical raster layers in QGIS”

PyGRASS equivalent of piping results from one function to another

When using GRASS commands on the command line, one very neat little trick is to ‘pipe’ results from one function directly to another. An example I used in an earlier post is:

r.category My_map | r.category My_map rules=-

So, how does that works in python using pygrass?
Continue reading “PyGRASS equivalent of piping results from one function to another”


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