Willkommen bei Sourcepole

Willkommen bei Sourcepole

Sourcepole bietet Produkte und Dienstleistungen in den Bereichen Linux, Open Source und Internet/Intranet-Infrastruktur an.

Die Haupttätigkeitsgebiete sind Komponenten und Lösungen für Geographische Informationsssteme sowie Integrationsarbeiten in diversen weiteren Gebieten.

Aufgrund unseres Linux- und Open Source-Software Knowhows können wir Ihnen leistungsfähige und an Ihre Bedürfnisse angepasste Lösungen anbieten, die auf dem reichhaltigen Angebot von Linux und/oder Open Source Soft- und Hardware aufbauen.

• Tuesday, 2012-03-20 11:00: FOSSGIS in Dessau, Germany starts with a workshop for programming QGIS plugins

  A great conference begins, with about 400 people attending presentations and workshops over three days.

• Tuesday, 2012-03-20 14:42: Changeset c27c89045c: “Add WFS support for QGIS server. Provided by René-Luc D’Hont”

  Wow.

• Tuesday, 2012-03-20 14.48: QGIS 1.7.4 uploaded to DebianGIS

  Ok, QGIS 1.7.4 is already a few weeks old. But current version on Debian is 1.4.0! This will be a long “new features” list for Debian users. Thanks for your work, Francesco!

• Tuesday, 2012-03-20 16:00: Marco Bernasocchi demonstrates a fully functional QGIS on a Android tablet.

  GPS support, right click gesture, pinch zooming and offline editing plugin working. Just a few tickets are left for uploading it to Android market. Hopefully we find another great student for this years follow-up GSoC project!

• Wednesday, 2012-03-21 16.05: Victor Olaya, author of SEXTANTE, announces his work on a QGIS processing framework with toolbox, graphical modeler, batch processing interface, etc.

  Wow!!

• Wednesday, 2012-03-21 18.30: QGIS and GRASS user meeting at FOSSGIS

  Explaining whats going on in the QGIS code and the QGIS community. Live demonstration of raster resampling branch.

• Wednesday, 2012-03-21 20.18: Tim announces QGIS 1.8 RC1 for April 9th.

  Test it before the hackfest in Lyon!

• Thursday, 2012-03-22 08:00: Bad news - three days in a row without any commit from jef!

  What happened? Jürgen forgot to bring his power adapter to Dessau :-(

• Thursday, 2012-03-22 13:30: FOSSGIS is over

  with well attended QGIS presentations and workshops.

• Thursday, 2012-03-22 23:37: Changeset 05f7d6baea “fix warnings”, authored by jef-n

  Jürgen is back home again. Phew!

• Friday, 2012-03-23 10:26: Changeset 585e58179d: Nathan Woodrow merges native MS SQL provider, written by Tamas Szekeres, into master.

  Good news for MS SQL users, but also for Tim: “Finally a way to stop having to use PostGIS all the time…”

What a week for QGIS! Looking forward to more news from the QGIS Hackfest in Lyon.

Die FOSSGIS und deutschsprachige Open Street Map Konferenz 2012 – die grösste deutschsprachige Anwenderkonferenz für Freie Geo-Informationssysteme und freie Geodaten – findet vom 20. bis 22. März 2012 an der Hochschule Anhalt in Dessau-Rosslau statt.

Sourcepole ist mit folgenden Vorträgen und Workshops vertreten:

• Neues vom QGIS Server und -Webclient
• TinyOWS - der schlanke WFS Server
• MapServer MapCache - der neue WMTS Tile Cache
• Workshop: Neue Funktionen in QGIS für Poweruser

Da mehr als 400 Teilnehmende erwartet werden, ist eine Registrierung bis zum 16. März 2012 notwendig. Das Anmeldeformular und andere organisatorische Informationen befinden sich auf der Konferenzseite.

Creating a shaded relief map from digital elevation data is a nice way to create a backround map for web mapping or other GIS work. Thanks to the know-how and the funding from the Swiss Humanitarian Aid Unit, QGIS now has a sophisticated function for relief map generation. The method is described in detail in an paper by Marc-André Bünzli. An important part of the method is the choice of the elevation colors. The QGIS plugin has the possibility to analyse the frequency distribution of the elevation values in the DEM and to propose color changes where significant changes in the histogram occure. It is of course also possible to modify the color scheme, to insert a completely different one in the dialog or to generat a shaded maps without color.

As illustrated below, the relief map is composed by three components modulated onto the final map to give it a more three-dimensional appearance. These intermediate steps are shown here to get a better understanding of the method. In QGIS, the user directly gets the combination as a result.

• The first component consists of a hillshade from north-west (300 degree) and an elevation color

• The second component is a hillshade and a gray value depending on the slope angle (darker is steeper). The hillshade angle of this second component differs to the first component by 15% to have better contrast in faces towards the light source. The second component is merged to the relief map with 30% weight.

• The third component consists of a hillshade from 270 degree and a yellow color in cells facing towards the light source. It is merged to the relief map with 10% weight

And the final relief map looks like this:

QGIS already offers a lot of possibilities to visualize raster data (contrast enhancement, color map, handling of transparent pixels, …) Last year, Radim Blazek refactored the raster provider interface and added on-the-fly reprojection support for rasters to QGIS. Very cool!

One of the few things currently missing in QGIS raster layer is the possibility to have other resampling types than nearest neighbour. The problem is that rasters appear pixelated when zooming further than the source raster resolution. So for applications like web mapping, it is important to interpolate the pixel colors and to have a broader display scale range for layers. In the last few weeks, I’ve added bilinear and cubic raster resampling to QGIS (thanks to Canton Solothurn for funding these activities!).

A lot of refactoring was necessary in the raster layer code to add resampling in a clean way. Therefore these changes are available in branch ‘raster_resampler’ of the QGIS github clone (git://github.com/mhugent/Quantum-GIS.git). It probably needs a longer period of testing to make sure every feature of the raster layer class still works properly.

The resampling option can be chosen in the raster properties dialog:

And here is the effect for a three band color image.

Nearest neighbour:

Bilinear:

Cubic:

And here for a palletted background map

Nearest neighbour:

Bilinear:

One would expect that considered the complexity of gdm there would be a way to have per user X11 options. So no, there isn’t one. At least not after the great rewrite after V2.22.

However good old Unix paradigms can help us (this is all under Debian, other Unices will allow a similar trick):

$ vim /usr/local/bin/X

Add something similar like this:

#!/bin/sh
#
# start X with different options depending on user

# check if the parent gdm process that started us contains
# "--username le_gamer" in its commandline
#
if ps -p $PPID -o args= | grep -q 'username le_gamer';
then
  exec /etc/X11/X.orig $* -config /etc/X11/xorg.conf.le_gamer
else
  exec /etc/X11/X.orig $*
fi

We check whether gdm is starting us and using the parameter “–username le_gamer”. If it is, then we’re using a different config file for X.

Of course you’ll need to adapt all this, unless you are using Debian or Ubuntu. You need to adapt the path to the X Server, to the config files etc.

Why did I do that? The problem is that Intel’s X server in Ubuntu Lucid Lynx 10.04 is really unstable with DRI on a Intel GM965/GL960 graphics card.

So unless I’m playing 3D games which are a lot faster with DRI, I don’t want to enable DRI (more over, “NoDRI” is pulling less power out of my battery). So my normal config contains this:

$ cat /etc/X11/xorg.conf
[...]
Section "Device"
        Identifier      "Configured Video Device"
        Option          "NoDRI"
EndSection

So now, the only thing you need to do is replace your “normal” X Server with the new “adaptable” one:

$ sudo mv /etc/X11/X /etc/X11/X.orig
$ ln -s /usr/local/bin/X /etc/X11/X

That’s it,

Tomáš Pospíšek