Archiv für den Monat: Februar 2012

Backporting stuff to Debian stable (6.0.x squeeze)

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Being a Debian User for a long time now, I can live quite well running Debian stable, because official backports and backports I build on my own, work around the problem of the long release cycles quite nicely.

This is arguably a little bit more work than updating to a recent Version of Ubuntu twice a year, but fortunately Debian does not tend to break on updates 😉

However, with Debian’s recent move to Multiarch support coming in the next major release (wheezy) building backports is currently not that easy as it used to be anymore.

Fortunately the Multiarch conversion howto gives some hints but naturally in a somewhat inverted way.

As I did not find a DE-multi-arch-HOWTO on the web, here is a 4-step mini HOWTO:

  1. Remove the following line from debian/rules (if present):
    DEB_HOST_MULTIARCH ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
  2. Remove all occurrences of $(DEB_HOST_MULTIARCH) in debian/rules (only the pattern itself, keep the surrounding stuff)
  3. Replace occurrences of /*/ in all files debian/*.install by a single /
    This can be done using the following command:
    for i in debian/*.install; do sed -i -e 's;/\*/;/;g' $i; done
  4. Remove all the lines starting with Multi-Arch: in debian/control

Hopefully this will be useful to other people crawling the web.

A Mapserver backend for Tirex

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When rendering maps people coming from a traditional GIS background tend to use Mapserver rather than Mapnik. I don’t know the reason for this, but it is probably just because Mapserver is quite mature and has been around for a long time while Mapnik is still relatively new.

I also did quite a few things using Mapserver in the past but mostly in the WMS and raster data area.

One thing Mapserver can do is rendering based on data values rather than just by predefined rules, which could be quite useful for river widths and the like. This was not possible in Mapnik at least not in Mapnik versions < 2.0.

Mapserver is scriptable in a couple of languages (not just Python) and this is why it has been relatively easy coding a new backend for Tirex although Perl is not quite my favourite scripting language. Of course this new backend is heavily based on the existing WMS backend.

So why did I do this? Well, last week I just stumbled upon the nice Topomap project which Max Berger is doing and unfortunately he map is limited to a very small area.

Hopefully I will be able to provide a map of this style for a couple of other areas real soon now. I’m especially interested in islands with good hiking options, the so called Wanderinseln in German.

I just commited the changes to the Openstreetmap SVN-repository in the hope that it might be useful for others as well.

BTW, Max is using TileCache which I could probably use as well. Probably someone can enlighten me about the pros and cons of Tirex vs. TileCache.