Esri File Based Geodatabases en Oracle connecties openen met QGIS

GDAL and OGR (www.gdal.org) libs from Frank van Warmerdam are famous software libraries which make it possible in the Open Source world to read and write a plethora of gis file formats. The nice thing about QGIS is that it using OGR and GDAL. So with every addition or enhancement in those libraries, QGIS itself is also getting better.
One example (while we offcourse ourselves will never use it 😉 ), is when somebody sents you a FGDB (File Geodatabase) from Esri. Since version 1.9, OGR can read and write with this format. Remark from the docs: “File GDB must be ArcGIS version 10, 9.3.1 is not supported.”
When using OGR 1.9 in QGIS, it is possible top epen FGDB fieles. Happily it is not difficult for Windows users to use OGR 1.9. If you use an OSGEO4W install of QGIS (see this post). If you checked ‘gdal filegdb’ QGIS should be able to open fgdb’s. For Linux users it is possible to get OGR 1.9 from repositories like ‘ubuntugis’ or ‘elgis’ see download.qgis.org.
To try this out we off course have to get a fgdb file… Googling you find them (off course) available at Esri. After a registration (!) you can download an example fgdb of North America.
Unzipping this you will find a directory ‘FileGDB API/samples/data’ in which you find directories with names ending with .gdb. One of those dirs is what Esri calls a FileGDB. There is not so much to see in those dirs. It is full with files having cryptic names like a00000015.gdbtablx a00000015.spx etc etc.
Happily QGIS kan handle this. Via menu or buttons go to ‘Add Vector Layer’ and select ‘Directory’. As ‘source choose ‘ESRI FileGDB’. If you do not have this as an option, you are apparently working with a OGR/GDAL version lower then 1.9 (see below how to find out) which cannot do fgdb. If you can, browse to the directory you .gdb directory we viewed before.

Select ‘topo.gdb’

After selecting this directory, it appears to hold several data sources: states, us_lakes, us_rivers etc. We select several of them.
Bingo. We see them as normal vector layers, and are able to style and edit them.

QGIS kan also open and visualize data from an Oracle Database.
Here the same adagio: only if your installed OGR library is capable of it: QGIS can do it. But if so: just open a connection to a database vector layer:



How kan you find out which ogr library you have installed and used by QGIS ?
Via the Help/About menu there is the tab ‘About’ which exactly shows you which libraries are used by QGIS, and which version of them:

How to find out which formats are compiled into your ogr/gdal libraries?
You have to go to a command line (via osgeo4w.bat in your osgeo4w directory if you are on windows):

c:\osgeo4w>ogrinfo --formats

en

c:\osgeo4w>gdalinfo --formats

This will give you a long list of formats that can be openedn. To check if fgdb (gdb) and Oracle (oci) are available, search for those strings in the output:

c:\osgeo4w>ogrinfo --formats | grep -i gdb
Supported Formats:
-> "FileGDB" (read/write)
c:\osgeo4w>ogrinfo --formats | grep -i oci
-> "OCI" (read/write)

How to get an org/gdal version which Hoe kom je aan een ogr/gdal die WEL fgdb en/of oracle ondersteund?
As told here above, for Windows users a QGIS install via OSGeo4w QGIS installatie met OSGeo4w is the best way (the standalone/msi installer of QGIS does not have these options).
For Linux user, compiling GDAL yourself is the (only?) solution. Reason for this is dat Oracle, Esri and Erdas do not want the Open Source community to (re)package their binaries. So you have to go all the way, and download the SDK’s and with that compile GDAL yourself.

QGIS installeren via osgeo4w

Most of the Windows users will install QGIS via the so called ‘stand alone installer’ which they download from download.qgis.org. For most of the users this is the easiest and most well know way to install a desktop program.
But QGIS has another Windows install possibility. And that is a so called osgeo4w installation ( osgeo4w.osgeo.org ). osgeo4w stands for ‘Open Source Geo For Windows’, and s a full blown working environment for Windows users with almost all open source geo components and libraries. After installation there is one directory on you harddisk which contains all osgeo4w related programs and libraries. You can for example install QGIS, but als command line programs like ogr2ogr or gdalinfo. Het is even possible to run mapserver from within apache in this way.

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Meerdere objecten / features tegelijk aanpassen / editten

Sometimes you find new QGIS functionality when a user asks you a question. Somebody working with house geometries was looking for a way to copy the same attributes to a set of selected houses. He was looking if certain types of houses in a city were usable for solarpanels on the roof. And often a block of houses share off course the same properties.
After a question on the QGIS-user mailinglist the answer came: “off course this is possible…”. Here a short demonstration of this.
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Invoerformulieren gebruiken in QGIS

QGIS has something called forms to make it easier to change te attributes of an object. This article is about the use of these forms. As exampel we use a dutch dataset of the houses of the netherlands (BAG) which only contain geometries and not other attributes. These we are going to add ourself.
We start with a shapefile with the house geometries. With the Python Plugin ‘Table Manager’ of Borys Jurgiel it is pretty easy to add columns to the shape file. Just adding a name and a type of th column. It is also possible to change the order of the columns in the shape file.

In this way we created a shape file with attritutes to help us to do our imaginary ‘solar panel’ research. For every house we want to know if the user is interested in solar energy. And if that is the case, also check what other properties the house and it’s roof has.
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Pff.. opslaan als dbf: general input/output error

Did you ever receive an Excell file to do some georeferencing, and thought: let’s save it as a dbf/Dbase4 format first. Because most FOSS gis application can handle that the best…
For some times I found this horrible error when trying to save it in Debian or Ubuntu: Error saving the document: General Error. General input/output error:
generalinput_outputerror dialog
Thinking it was an old Open/LibreOffice bug which was not to be fixed because nobody will use dbf files anymore…
Wrong! It’s just the fact that I/you did not install libreoffice-base / openoffice-base package in Ubuntu! Apparently this is not installed by default. After a thorough:

sudo apt-get install libreoffice-base

It will just work!!
see https://bugs.launchpad.net/ubuntu/+source/openoffice.org/+bug/502462
Thanks…