Ubuntu 13.04 and QGIS

Ubuntu 13.04 and QGIS

As usual, when a new version of Ubuntu comes out, I allow myself to be guinea pig and test for Ubuntu-QGIS compatibility. Some QGIS incompatibility may occur but patch updates usually follows within the next few days. Yesterday, my 64 bit dual boot computer had its Ubuntu upgraded online. Everything went well. Using Ubuntu Software Centre, I uninstalled and re-installed my QGIS just because I wanted to start from scratch. QGIS 1.7.5 was easily installed in one click this way but after activation, this message 'Couldn't load PyQGIS' came out. It basically said the Python API file was not updated from V8.1 to V9.0-9.2 as required by the Raring Ringtail version. I still could activate a landuse plan, add colours with my qml colour template but 'Fetch Python Plugins' was missing. This was serious because I often use Google Maps. Re-installation via terminal mode brought the same result and the Synaptic Package Manager could not help either. I decided to take the long cut and install the Master version. Conclusion? It was a success! QGIS 1.9.0 may look slightly different because familiar icons were re-designed but Fetch Python Plugins menu is there! My wordless step-by-step installation is below and I recommend double-clicking the images for a better view. The installation procedure basically involves:

• Copying nightly builds from the QGIS website to the Software & Updates;
• Copying qgis.org repository public key from the QGIS website to the Terminal;
• Configuring and running the Synaptic Package Manager;
• Installing update.

It should be the RARING not Quantal build. Sorry, copy & paste error.

When is a silverfish not a silverfish?

When is a silverfish not a silverfish?

When I tried hands-on at editing landuse plans, I realized upon zooming in, the existence of 'silverfishs' here and there. This was probably because these digital plans had their roots in CAD drawings and I assume that their occurrence would not been had they been created by GIS software instead. Anyway, I did not have any problem deleting them until I came across some which I simply could not. I was baffled. No matter how much I zoomed in, I just could not delete the stubborn silverfish not until I accidentally clicked and moved a node away from the centre of the line exposing it to be a polygon hiding behind the skirt of a line. I then selected that polygon and successfully deleted it. Sometimes, the third node overlaps seamlessly behind a vertex node giving the impression it is a simple line and until you move it, you won't hear it say "Trick you!"  Conclusion: What you see on a GIS layout not necessarily is what it is.

Updating the existing landuse plan

Difference used

Ouput

Unwanted lines need cleaning

Union used

Output

Pengemaskinian pelan gunatanah semasa

Dalam QGIS, modul Difference dan Union dibawah Data Management Tools diperlukan untuk mengemaskini pelan gunatanah semasa. Andainya unjuran peta antara pelan leaut dan pelan gunatanah semasa adalah sama, gabungan adalah mudah. Bagaimana pun, sekiranya apabila lot berkaitan telah dikeluarkan dan ternampak garisan atau silverfish, maka tindakan sewajar perlu diambil untuk "membersihkannya" sebelum mengabungan pelan leaut dengan pelan gunatanah semasa. Mudah saja...kalau tahu bagaimana.

Updating the existing landuse plan

In QGIS, the Difference and Union module are the modules under Data Management Tools required to update the existing landuse plan. On the assumption the map projection between the approved layout plan and the exisitng landuse plan are the same, the merge is simple. However, if upon deleting the affected lot, lines or silverfish appear then masures must be taken to first clean that before merging the approved layout plan with the existing landuse plan. Simple...if you know how.