I decided to improve my MergeShapes plugin a bit. I added encoding selection when opening files, shapefile geometry type selection and reworked the merge algorithm. Now, the final attribute table contains all unique fields from all input files, which means you can merge files with different attribute tables. The only missing bit is a setting for the default encoding of input data.
There are plans to improve DPSimplify, Statist and RasterCalc, but I don’t know how it will go yet.
I’ve also started to slowly learn Git, or rather to organise and deepen my fragmentary knowledge. I want to try out this VCS in real tasks, as there is already a Git mirror of the main QGIS SVN repository.
Based on the report published on the Linfiity Geo Blog and my own impressions.
The 4th QGIS hackfest, held from 11 to 15 November in Wrocław, Poland, attracted 29 participants (28 people and one dog). All participants did their best to make QGIS even better. A lot was accomplished in four days: hundreds of commits, demonstrations of new features, and many productive discussions. The meeting was organised by Paweł Netzel with the help of Milena Nowotarska, Robert Szczepanek, Maciej Sieczka and Borys Jurgiel and took place at the Department of Climatology and Atmospheric Protection of the University of Wroclaw.
My contribution — numerous improvements to the fTools plugin. When using the “Merge shapefiles to one” tool, it is now possible to select not only a folder, but also individual files. The “Simplify geometry” tool has been redesigned: I added a customisable simplification threshold and the ability to simplify the whole layer or only selected features; simplification can be done “in place” or by creating a new shapefile; “in place” simplification supports undo/redo; at the end of the simplification plugin shows a report about the total number of vertices in a layer before and after simplification.
Below, you will find an overview of the most important topics that were discussed during the hackfest as well as most notable changes.
Yesterday I found out that my plugin — RasterCalc — was only announced on the QGIS mailing lists. I didn’t post anything on the forum or here. I don’t know how I could have forgotten. Although I have to admit that there was a lot of work going on at the time: RasterCalc itself, an experimental branch of GDAL Tools, Photo2Shape and many other things. QGIS 1.4 was released in January… I know it’s a weak excuse, especially considering that other plugins were announced all over the place, but I don’t have any others.
So… RasterCalc is a user-friendly and functional raster calculator written in Python. It was announced on the mailing lists on 16 January 2010.
RasterCalc window
RasterCalc was inspired by Barry Rowlingson’s RasterLang plugin. The main difference is the user-friendly interface and the familiar expression syntax (do you like LISP as much as Barry?). I have also added some additional features like saving and loading expressions, “templates” of formulas and extended the set of available functions and operators.
Weeks and months went by (I almost wrote “years”), nothing seemed to indicate any changes… And then, out of the blue, Marco Hugentobler and Tim Sutton decided to make RasterCalc part of the QGIS analysis library. This will allow its features to be used by other plugins, and remove the dependency on NumPy, pyparsing and other Python modules.
Marco has already published a first version of the patch. Some features are missing compared to the original plugin:
there is no support for “templates” of formulas (in RasterCalc there are two: “Difference” and “NDVI”)
the result can only be saved with Float32 data type
saving and loading of expressions is not supported
At the same time, new features have been added:
it is possible to specify the desired resolution and extent of the result. This allows rasters with different resolutions to be used in one expression. If necessary, the rasters are automatically resampled to the output resolution
result can be saved in various formats, not only GeoTiff
QGIS Raster Calculator
You can try out the new functionality by applying the patch and building QGIS from source. The calculator will appear in the “Layer → Raster calculator” menu.
The patch is still under development and some things may not work. The authors invite everyone to try it and report any bugs (if possible, attach a test dataset and steps to reproduce the issue).
Yay! The collaborative project to translate the QGIS 1.5 User Guide into Russian is finished. It took 1 month and 18 days, and 15 people participated.
During the translation process, many typos and inaccuracies were found, which, in the best tradition of open source, were corrected not only in the translated version but also in the original manual. Thanks to the perseverance of the project members, several major problems in the English version, such as the lack of a subject index and bibliography, have been fixed.
The translated user manual (PDF format, ~10 Mb) is now available on the QGIS website.
A collaborative project to translate the QGIS 1.5 User Guide into Russian is announced. I will lead and coordinate the project. Please share information and get involved, and don’t hesitate to contact me if you have any questions.
Marco Hugentobler wants to merge his project, QGIS mapserver, into the QGIS source code.
QGIS mapserver is an open source WMS server that runs on Linux, Windows and Mac OS X (other Unix-like systems should also be supported, but have not been tested). The server is a FastCGI application written in C++. It uses QGIS libraries for rendering and GIS operations.
Among the main features:
support for GetCapabilities, GetMap, GetStyle, GetFeatureInfo requests and customisable styles based on the Styled Layer Descriptor specification (supported standards include WMS 1.3.0, WMS 1.1.1 and SLD 1.0.0).
SOAP over HTTP POST. Compatibility with ORCHESTRA and SANY Service Oriented Architecture
SLD extensions (diagrams and custom symbols in SVG format)
I returned to Zaporizhzhia yesterday, sunburned and a little refreshed. The heat in Crimea is terrible, and the proximity of the sea does not help. In Choban-Kale, at 11 o’clock in the afternoon, we had 53°C in the direct sun (they say it was almost 60°C in Simeiz), and the water temperature was ~28–29°C. However, it is no better in Zaporizhzhia.
While I was on holiday, the next version of QGIS — 1.5.0 “Tethys” — was released. The official announcement is on the QGIS blog. There are many changes: a lot of bugs have been fixed, new tools have been added, and old tools have been improved (fTools, GdalTools, annotations, new georeferencing module). The documentation is actively updated.
Marco Hugentobler has implemented initial support for table joins in QGIS. If you want to try out the new functionality, you can get the source code from the new branch of the repository
svn co https://svn.osgeo.org/qgis/branches/table_join_branch table_join
and build it.
To join a table to a layer’s attribute table, you need:
add a vector layer to a project
add a table to a project (e.g. by going to the “Layer → Add vector layer” menu and selecting a *.csv or *.dbf file)
open the vector layer properties dialog and select a “Join” section. Then click on a “+” button to add a new joinJoining a table to a vector layer
select the fields that will be used to create the join and press “OK” button
new fields from the joined table should appear in the layer’s attribute table, as well as in the “Attributes” tab of the layer properties dialogue and in the “Identify Results” dialogue
As this feature is still in the early stages of development, there are some issues:
joined fields are read-only, their values cannot be changed
poor performance, especially when performing classification or searching on joined fields
I have noticed that recently many people have asked how to get image coordinates (row, column) from real world coordinates (latitude/longitude). The following code shows how to do this in the QGIS Python console:
GdalTools (or Raster Tools) is a plugin for the open source GIS QGIS. The main purpose of the plugin is to simplify the use of the GDAL command line utilities by providing the user with a graphical interface for the most common operations.
Initially, the plugin was developed by Faunalia, later other developers, including myself, joined them. Robert Szczepanek created nice icons for most of the tools, and the development of some features was sponsored by Silvio Grosso.
At the time of the first announcement (September 2009), the plugin provided only two tools: gdalbuildvrt and gdal_contour. Now the number of integrated tools is approaching 20.
