I just noticed that someone has created official Debian packages for Osmium (for sid). They have also found their way into the new Ubuntu 12.04 version. Unfortunately they are already outdated. It is fine if you only want to use osmjs, but if you do any development based on Osmium, I suggest you use the version from github.

For a while now I have been working on OSMCoastline adding features bit by bit. (See this blog article for some background info.) OSMCoastline now closes small gaps in the coastline and it can split up the huge polygons into smaller ones. You can create land polygons or water polygons depending on your needs and you can have it all in WGS84 or in the usual Mercator projection used for tiles web maps (EPSG 3857). So it does a lot more than the coastcheck application used for these things before. And the software is still a lot faster.

Today the April 2012 issue of the German computer magazine “iX” was in my mailbox. It contains my four and a half page article on how to create your own maps with OSM data. I describe how to use Osmium/osmjs software to extract the data and Tilemill to style and create the maps.

I gave two talks at the FOSSGIS 2012 conference last week. The first, OpenStreetMap in Zahlen und Karten, was not recorded and I will not release the slides as they will be difficult to understand and easy to mis-understand without my words. I will probably re-use the content for a few blog articles here in the future.

Next week is the FOSSGIS conference in Dessau. I’ll be speaking there about OpenStreetMap in Zahlen und Karten and Das Osmium-Framework. Together with Tim Alder I am also organising a community session to discuss the Wikipedia Multilingual Maps Project. See you in Dessau!

Every map of the world has to take into account that there are land areas and water areas. You could have huge polygons for each continent and paint them on a blue background. But handling those huge polygons is difficult. OpenStreetMap solves this problem by having ways tagged with “natural=coastline” and the convention that the land is always on the left side of this way. So a continent or an island is surrounded by one or more ways in counter-clockwise order. It is much easier to edit those coastlines instead of large multipolygon relations or something like it. Coastlines are the only case where OSM has this special rule.

The Karlsruhe Hacking Weekend is over. 18 people were there at least part of the time. I had a lot of fun and even got a little bit of work done: As mention I worked on Taginfo and on the second day I worked a bit on the statistics for my upcoming talk at the FOSSGIS conference. I am using Osmium and full-history planet dumps to see what has been happening in OSM. I’ll publish some code and graphics at some point.

The Karlsruhe Hacking Weekend is in full swing. About 15 people are sitting around, munching apples, pizza and Gummi Bears and talking about things “somebody” should do “someday”. And we do some actual work, too. I fixed a few bugs in Taginfo, Sven and others are working on updating the German map style. Some people are talking about obscure Mapnik config options. No idea what the other people are doing.

I recently started writing my own RSS and Atom feed reader. I’ll write another blog post about why and how I am doing that. Today I want to focus just on one part of the job: Reading the RSS and Atom feeds.

The Osmium framework has been around for about a year and a half now and has grown to include a lot of functionality. But there is still much to to. In this blog post, I have collected some of those things. There is no particular order to the following list.

In recent Linux kernels something changed in the way CDROM/DVD ejects are handled. On my notebook with current Ubuntu (11.10) the result was that “eject -i” does not work any more to block the physical eject button. Thats very annoying as I kept hitting it accidentally. But I found a way to get it working again: Copy /lib/udev/rules.d/60-cdrom_id.rules to /etc/udev/rules.d and comment out the line with DISC_EJECT_REQUEST. Now “eject -i” works again.

Time for the next OpenStreetMap hack weekend. Hope to see you there.

Lately I have been working on OSM-derived data in QGIS and finding bugs in the OSM data in the process. To fix the data I have to go into an OSM editor (that’s JOSM for me), find the right position and do the actual fix. To make that process easier I added a button to the QGIS user interface that uses the JOSM remote control feature to tell the editor which area to load data for.

I spend a lot of time slicing and dicing OSM and other geodata. Sometimes that is done with custom software but often a database is involved somewhere. Recently that sometimes has been the SQLite/SpatiaLite duo which works great for simple things. But the heavy lifting has to be done with PostgreSQL/PostGIS which has much more “geo functionality” and is much faster when complex queries are used. So here comes the first tip:

While working with OpenStreetMap or other geodata I often stumble upon interesting (or just pretty) visualization of the data. I have started a collection on my Miscellaneous Maps Flickr set. Some of these maps were created “on purpose”, some just appeared on my screen by accident. Maybe it inspires someone to create their own whacky visualizations.

Osmium now includes OGR support. OGR is a popular Open Source library for converting different GIS storage formats into each other. It supports PostGIS, Shapefiles, Spatialite, and many other formats. I had started working on OGR integration many weeks ago, but didn’t quite finish it. I have now added the last bit: Support for OGR Multipolygons. This opens up a lot of new possibilities for Osmium users.

More and more boundaries of administrative areas find their way into OpenStreetMap. In some countries there is already quite a lot of data for several levels of government. Unfortunately it is hard to edit and hard to use because relations must be used to model areas in OSM and relations are notoriously difficult to handle. Relations and with it the areas they represent are often broken as a result. Its therefore hard to get a complete set of administrative areas for a particular country and level of government.

Osmium is getting bigger and bigger and doing more and more. But testing the code is still done manually and ad-hoc. Not good. I have used some testing frameworks in other languages, but never in C++. As usual, Boost comes to the rescue. I recently added some test code using the Boost Unit Test Framework which (at least for now) does all I need.

Martijn van Exel is organizing a hack weekend on June 10-12 2011 at the Linuxhotel. I am planning to be there. After many hack weekends in London this ist the first such event in Essen after a long time. The first OSM event at the Linuxhotel was the Essen Developers Workshop I organized there four years ago. Has it already been that long?.

The organisers of the State of the Map Europe have published the programme and it looks very interesting. I will give a talk about Taginfo and a talk about Osmium, the two projects I currently spend my free time on.

Yesterday I gave a talk about Taginfo at the FOSSGIS2011 conference. The talk is in German, you can download a video (570 MB MP4). Many thanks to the volunteers who created the awesome videos of all the OSM talks at FOSSGIS!

It is quite amazing what can be done with good data and current map rendering technology. Mapnik and other renderers have continually pushed the envelope and there are many examples of beautiful maps out there.

The Unicode character set contains somewhat over one million code points from 0 to hex 10ffff. That wasn’t always so. Unicode started out with only 16 bit characters, or about 65000 code points. At some point it was decided that that wasn’t enough and the version 2.0 released in 1996 switched to the larger character set.

Taginfo always had an API so everybody can access all the juicy data in its database through simple HTTP queries. But that API was never used by anyone (as far as I can tell from a quick look at the log files). One reason was probably that I didn’t document the API.

In the past week two people conntacted me independently who are working on Taginfo sites with local information for Ireland and Brazil. This prompted me to work on Taginfo again. Taginfo was never intended to be run on more than one web site, but it makes sense for other people to use it, too. So I incorporated some stuff that makes it easier to do that. Taginfo now has a new icon in the top left corner that can be changed for each instance, when you click on it you get some local information. Taginfo sites can add their address to the wiki.

I have wanted to play around with NodeJS for a while. I had some time on the weekend so I implemented a small tileserver for Tirex using NodeJS.

Even hotels that are proud of being different are similar in a way. Ideally there might be different experiences to be had, but somehow they are all standard. At least in the bathroom.

Some month ago I introduced Taginfo and mentioned there in passing that the statistics collection is done based on a C++ framework called Osmium. I promised another post and I am delivering on this promise now. I have been working on Osmium on and off over the last 6 months or so and, while it is far from perfect, I think it could be actually useful for other people now. So lets dive right in. What is Osmium and what is it good for?

The OpenStreetMap database currently contains nearly 900 Million nodes. Because some nodes have already been deleted the highest node ID is already past 1 Billion. IDs in the database are already 64 bit wide so that space will not run out. But lots of software only uses 32 bit IDs. There recently was a question on the German mailing list when the 32 bit would run out, so I want to give some answers here.

Yesterday Frederik Ramm send me a link to this wikipedia page. It contains 73 observations on (mostly obnoxious) behaviour in the Wikipedia and some recommendations how to deal with it. Almost all of that can be translated directly to OpenStreetMap and I recommend that every OSMer read it.

On the weekend there was (again) a discussion on the German OpenStreetMap mailinglist about how the system of coming up with new OSM tags and better defining existing tags could be improved (or whether it actually needs improving). This is a difficult subject. The “system” (for lack of a better word) is confusing and often leads to frustration. But it does basically work. OSM is growing, people are entering more and different kinds of data, usable maps are produced, finding routes based on OSM data works.

One of the things I like to do when on holiday is spending huge amounts of time and money in book shops and then more time reading the books. And inevitably the time runs out faster than the books, so my stack of unread books keeps growing. I recently added a new bookshelf conventiently located near my bed just for the unread books. There are just too many interesting things and interesting books about those things out there…

The OpenStreetMap project gets bigger every day. More people edit the data which leads to more data in the database and this to more people using the data. And with the growing database it gets harder and harder to see whats in there. Gone are the days when the common mapper would need to know maybe a dozen different tag keys, each with just a handful of typical values. Today people tag parking spaces and public transport, power lines and penguin pools in their local zoo. Some people are valiantly trying to keep up by documenting tags in the wiki, but sometimes that seems to be a lost cause. There are only about 550 wiki pages describing a key, but there are about 20,000 different keys in the database (about one third only used once, many will by typos) not to mention the 50 Million different tags. What are all these tags? How are they used and by whom? The endless discussions on the mailing lists about what tags to use are partly because the world is complex and fitting everything in our tagging model is not easy, but they are also in part a symptom of this confusing situation.