Category Archives: GIS

Access GRASS 7 data in QGIS

QGIS supports GRASS in two different ways. 1) For those working with GRASS databases, there is the GRASS toolbox, which basically offered an alternative GUI to GRASS. For those working with other data types, most GRASS functions are now available through the processing toolbox.

I do most of my spatial analysis in GRASS, while I use QGIS amongst others to create maps based on the results. So I mostly used the GRASS toolbox. Unfortunately, the GRASS toolbox doesn’t work (yet) in QGIS 2.6. So what now? Well, as it turns out, QGIS can access GRASS raster layers through the QGIS browser. Continue reading

Locus Map Pro carries its support for MBTiles to the next level

I wrote before about the MBtiles format, a convenient format to store tiled maps in a single portable sqlite database. Probably the easiest way to create them is with Tilemill, as described here. The format is supported by amongst others QGIS, but it is especially suitable for use with map viewers on your mobile device.

The format is now supported by various mobile map viewers, including e.g., Geopaparazzi and OruxMaps. One I like for its rich set of features is Locus Map Pro. I normally only write about open source, but I think the developer of this app deserves some credit for being one of the first (as far as I am aware of) to support the MBtiles format.  Up to very recently you could only view maps in MBtiles format (similar to the other viewers mentioned above), but with the latest update support for the UTFgrid feature has been added.This basically adds interactivity to your map.
Continue reading

The all new and shiny QGIS 2.6 is out

QGIS Brighton (2.6) is out, with tons of new features and improvements. Check it out on http://qgis.org/.

For an overview of the new features, check out this change log. You really should check it out. I just had a look and although I am using the trunk and beta versions for some time now, I still noticed quite a few new features I hadn’t discovered yet!

GRASS GIS 7.0.0 beta 3 is out, bringing further fixes and improvements

GRASS 7 sports very significant improvements and numerous new functions. For example, the improved graphical user interface makes it much easier to carry out complex GIS operations and handling of vector data has become much faster and more efficient with very large files. There is a large number of new analytical raster and vector modules and existing modules are now much faster (some even 1000 x faster). Beta 3 ships 390 fixes and improvements with respect to beta 2. For more details, go to http://grass.osgeo.org/news/37/15/GRASS-GIS-7-0-0-beta3/.

Exporting your GRASS raster using r.out.gdal? Check the createopt options!

GRASS GIS can export your raster layer in most common (and quite a few less common) data formats using the r.out.gdal function (menu: file – export raster map – common raster formats). Exporting is so simple that you may forget that depending on the output format there are different options to optimise your output raster layer. Continue reading

Sampling raster values at point locations in QGIS – an update

In a by now fairly old post I described how to sample raster values at point location in QGIS. The method I described used the ‘Point Sampling Tool’ addon. However, the function creates a new point layer, which only contains the values extracted from the raster layer. None of the fields in the original point layer is copied to the new one. It is possible to join the attribute table of the new vector point layer with the original attribute table afterwards using a spatial join as explained in that post. However, this will not work if your point data includes points with exactly the same coordinates.

Since I wrote that post, QGIS has come a long way. Continue reading