Current projects

06.10.2010 16:20 ·  Notes  ·  life

The collaborative project to translate the QGIS 1.5 User Guide into Russian is nearing completion. I’m busy with the final editing and formatting.

Recently, I had to look into the OGC CSW (Catalogue Service Web) standard. It’s an interesting and useful thing, but most of the public servers I managed to find implement various aspects of it in a strange way :-(. So I have to add a monstrous construction to the code to catch exceptions and give the user a more or less understandable error message.

I am also slowly writing Pascal wrappers for the GDAL/OGR and Proj libraries. I couldn’t find any Pascal bindings for GDAL/OGR, so I’m making my own. I already have a more or less working module for OGR and some examples of its use. A module for OSR is also ready, but has not been tested yet. Next in line is a module for GDAL.

The situation with the Proj wrapper was a bit more interesting: first, I found a Pascal module for Proj 4.4.3 (the current Proj version is 4.7.0), and this wrapper required changes to the source code of the Proj library. I didn’t like this approach and started to make my own module, partly based on the one I found. Later, when updating the FPC compiler, I accidentally noticed that the available packages included modules for Proj 4.6.1. Now I’m not sure what to do: should I continue developing my own wrapper or not?

I plan to push the results of my work upstream, and if that doesn’t work, I’ll just publish them somewhere.

QGIS 1.5 User Guide translation

25.08.2010 16:37 ·  GIS  ·  qgis

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.

QGIS mapserver

20.08.2010 15:17 ·  GIS  ·  qgis

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)

QGIS 1.5 "Tethys"

06.08.2010 10:30 ·  Notes, GIS  ·  qgis, release

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.

Going on vacations

26.07.2010 15:01 ·  Notes  ·  vacations

I am leaving for Crimea tomorrow morning at 6 a.m. and will be back late in the afternoon on the 5th.

I will not have internet access there, but you can write to me :-). I promise to answer all emails, comments, bug reports and feature requests when I’m back.

Table joins in QGIS

22.07.2010 14:44 ·  GIS  ·  qgis

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 join

  

• 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

Geographic coordinates to raster (row, column) coordinates

21.07.2010 15:37 ·  GIS  ·  qgis, python, howto

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:

import math # needed for floor() function
iface = qgis.utils.iface
# let's assume that raster is a current layer
layer = iface.mapCanvas().currentLayer()
# geographic coordinates
x = 75.0791666
y = 57.2541666
extent = layer.extent()
width = layer.width()
height = layer.height()
# raster resolution (pixel size)
xres = (extent.xMaximum() - extent.xMinimum()) / width
yres = (extent.yMaximum() - extent.yMinimum()) / height
# calculate raster coordinates (row and column)
col = int(math.floor((x - extent.xMinimum()) / xres))
row = int(math.floor((extent.yMaximum() - y) / yres))

Nothing complicated or fancy. The same code can be used in plugin with minimal changes.

GdalTools — QGIS plugin for raster data processing

06.06.2010 13:07 ·  GIS  ·  qgis, plugins, gdaltools

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.

Nature by Numbers

13.05.2010 14:49 ·  Notes  ·  video

I really liked it, cool video.

For those interested, there’s a theoretical part.

New ISP

07.05.2010 16:41 ·  Notes  ·  life

I have been using PeopleNET as my ISP for quite some time. The speed was not very high, and the only plan available was pay-per-gigabyte. But it was more than enough for email, jabber and most websites.

There were simply no other options. Ukrtelecom cited a lack of technical capacity and offered to pay a fee and wait for the capacity to appear (they could not give an estimate of how long this would take). Beeline said they couldn’t provide service to this address, although they had connected the house next door. And there have never been any LANs in our neighbourhood, and if there were, they were very far away and not for a long time.

The Telza ISP didn’t make any excuses or problems, they just pulled the cable through a block and a half. So now I have internet like this

And PeopleNET was left as a backup and travelling option. Their USB modem fits perfectly into the small pocket of a laptop bag.