Category: GIS

"Tip of the day" in QGIS

19.02.2011 18:35 ·  GIS  ·  qgis

In the commit 15199 Tim Sutton added tips shown on QGIS startup. Those tips can be enabled/disabled in the QGIS settings.

So far, the number of tips is very small — about a dozen. Anyone who wants to can submit their tips for inclusion. The requirements are simple:

A bit earlier, in commit 15195, a separate window was added with a list of organisations that supported (and support) the project financially, i.e. sponsors.

RasterCalc 0.2

15.02.2011 18:00 ·  GIS  ·  qgis, plugins, rastercalc

I have just released RasterCalc 0.2 with conditional operators support.

Beer feedback and bug reports can be sent to the author.

P.S.: Git is extremely powerful and easy to use.

Adding a layer list widget to a PyQGIS application

14.02.2011 09:31 ·  GIS  ·  qgis, python, howto

QGIS is not only a ready-to-use desktop GIS, but also a set of libraries that can be used to create custom GIS applications. Unfortunately, when creating such applications, developers have to implement some GUI elements from scratch. An example of such a widget is the list of loaded layers (sometimes incorrectly called a legend).

In this post I will show the process of embedding a layer list widget into a PyQGIS application. The widget was developed by Germán Carrillo and you can get the code and read how to use it in Germán’s post “Layer list widget for PyQGIS applications” on the GeoTux blog.

Read more ››

Export/import of symbology in QGIS

06.02.2011 17:05 ·  GIS  ·  qgis

The so-called “new symbology” in QGIS has an impressive set of features and allows users to create their own symbols from the simplest to the most complex. Unfortunately, it does not provide a mechanism for sharing symbols, and it is not possible to use multiple symbol libraries at the same time.

I decided to fix at least some of the shortcomings and prepared a patch that allows the import/export of symbols. This is the third patch of this kind among my fixes, the previous two were also import/export related (one for import/export of PostGIS and WMS connection settings, and the other for import/export of custom keyboard shortcuts).

Symbology export dialog
Symbology export dialog

Conditional operator in RasterCalc

03.02.2011 19:24 ·  GIS  ·  qgis, plugins, rastercalc

Despite the fact that QGIS now has a built-in raster calculator, the RasterCalc plugin I developed is still quite popular. I don’t know how to explain it: either it’s a matter of habit, or my calculator is more convenient… I’d like to know what the reason is, maybe I should make a poll.

Why this preface? For a long time, I’ve been “terrorised” by requests to add support for conditional operators to my plugin. The one guy from Spain was particularly active. And no matter how often I pointed out that I was busy with other projects, no matter how hard I tried to avoid it, nothing helped. After a short break, the “attacks” were repeated. Apparently, they had decided to wear me down.

The inclusion of a patch that added comparison operators (submitted by Ghislain Picard) didn’t help either. It was not enough, and it was not what they were looking for. People wanted more, something similar to r.mapcalc from GRASS and preferably with the same syntax.

Well… I have to admit, they got it. Today this most wanted feature is implemented. However, the syntax is different from r.mapcalc’s, because I didn’t want to make the already complex parsing code even more complicated. Now you can do things like:

This nice feature is still in my local repository. I will not commit it to the public repository until the documentation has been updated. And I really don’t have the mood or energy to do that. I don’t like writing, whether it’s an essay, an article, or anything else. There are times when it is easy to write, but those are rare.

There is another reason or two, to be precise and honest. Firstly, I’m thinking about optimising the plugin a bit: operations on large rasters use a lot of CPU and memory. And secondly, that very active Spaniard made another feature request the other day, and I have a feeling that he will be as persistent in his efforts to get me to implement it as he was before.

But I haven’t made a final decision yet. Maybe the conditional operator should be enough for a new version and I should not bother with refactoring and optimisation? Or should I wait a bit, but release an even more powerful calculator and consolidate the success of the first versions?

News from the world of GIS

29.01.2011 09:21 ·  GIS  ·  qgis, gdal, osgeo4w

Alessandro Furieri has announced the SpatiaLite Cookbook, an excellent guide to SpatiaLite with many practical examples, optimisation tips and information on using SpatiaLite with different programming languages. You can check it out here.

Frank Warmerdam has announced that OSGeo4W is moving to the recently released GDAL 1.8.0. Instead of GDAL 1.5.4, the default version will be 1.8.0, additional packages like gdal-python, gdal-autotest, gdal-ecw etc. will also be updated or removed if no longer needed.

For compatibility with some packages that still require GDAL 1.5.4, a new package gdal15dll (with the necessary libraries) will be added. This package will be automatically installed if needed.

Since the transition to a new version of GDAL is a rather laborious and time-consuming process, the update of some packages included in OSGeo4W is temporarily suspended. In particular, this affects QGIS nightly builds.

The maintainers of the QGIS OSGeo4W package have already announced that they will rebuild the package with GDAL 1.8.0 as soon as possible, GRASS will be rebuilt after GRASS 6.4.1 is released.

kCube will be fixing bugs

12.01.2011 15:25 ·  GIS  ·  qgis

A work front has been selected for the kCube developer. SunilRaj Kiran will work on QGIS bugfixing for 6 months.

If you are interested, you can find out more about kCube and the new developer in an interview that Tim has published.

The first three issues he will work on have already been selected: #13034, #13215 and #12301.

CSWClient plugin for QGIS

06.01.2011 07:03 ·  GIS  ·  qgis, plugins, cswclient

I have released a first experimental version of the CSWClient plugin for QGIS.

The plugin interacts with the OGC CSW (Catalogue Service for Web) servers and is used to search and view spatial data and related resources.

CSWClient plugin dialog
CSWClient plugin dialog

Among the main features of the plugin:

CSWClient is available from the QGIS plugins repository.

The plugin was developed for Linfinity Consulting for the TanBIF (Tanzania Biodiversity Information Facility) project.

kCube poll

21.12.2010 06:59 ·  GIS  ·  qgis

A few days ago I wrote about the kCube Consulting initiative. The ideas have been collected, and the voting has started. Unfortunately, you can only vote for one option.

So far “Fixing bugs” is leading with 23.8%, followed by “Improving import/export on dwg/dxf” with 8.8% and “QGIS Mobile (e.g. on Android)” with 7.5%.

QGIS Plugin Manager with icons

13.12.2010 17:19 ·  GIS  ·  qgis

This is how the QGIS Plugin Manager looks like after adding icons to plugins.

QGIS Plugin Manager with icons
QGIS Plugin Manager with icons