We interview Julien Minit about his OpenStreetMap-based hiking map style OpenArdenneMap
For the March 2025 edition of our interview series with OpenStreetMap communities around the world, it is our pleasure to chat with Julien Minet about OpenArdenneMap, a map style he has developed for hiking (specifically in the Ardennes region of his native Belgium).
1. Who are you and what do you do? What got you into OpenStreetMap?
I work in the field of geomatics and have been contributing to OpenStreetMap for many years. I started contributing to OpenStreetMap in 2012. Then I contributed more and more. In 2017, I joined the cooperative company Champs-Libres, where I work, because it was the only company working with OpenStreetMap data in Belgium. So you could say that I found my job thanks to OpenStreetMap.
I’ve always been interested in cartography. After my studies, I started to get interested in software for making maps on the web, at the time MapServer and OpenLayers… My aim was to make maps, especially on the web, to show things that weren’t very visible. For example, I made a map of community gardens in Brussels in 2010. Then I slowly saw the rise of OpenStreetMap. But at first I didn’t believe in it: the map was mainly empty and had poor accuracy, so I didn’t think OpenStreetMap would ever be mature enough to make good maps. I was wrong.
Today I’m an active contributor to OpenStreetMap and I’m also a member of the OpenStreetMap - Belgium local chapter association. I often meet other contributors in Belgium, and we form a super-community: people who are open and passionate! I regularly co-organise OpenStreetMap meetings in my region and I lobby for OpenStreetMap just about everywhere!
2. What is the OpenArdenneMap project and why was it created? Who uses it? How?
When I started contributing to OpenStreetMap, I quickly became interested in generating topographic maps. I first saw the OpenTopoMap project, then a project to reproduce the maps of the national geographical institute in France. At first, my challenge was to be able to produce maps that looked like those of the Belgian National Geographical Institute. It was above all a technical challenge for me, as I was just starting to learn how to code. I spent a long time looking for the best software for this. First I tried MapServer, which I knew. Then I switched to Mapnik, which is the cartographic software used to generate the basic style available on openstreetmap.org and on lots of other cartographic projects, including OpenTopoMap. Very recently, in 2022, I translated the OpenArdenneMap style into QGIS.
Today, OpenArdenneMap is a cartographic style that can be used with Mapnik or QGIS, the 2 being maintained in parallel without being 100% equivalent. OpenArdenneMap is a style designed for printing, not for web maps. The main difference between a map style for printing and web maps is that the labels are about twice as large as on a web map, but there are other subtleties, such as the choice of colours, contrast, etc. I use this style with my colleagues to generate maps that can be downloaded from the hiking.osm.be website. These maps are free to download and a financial contribution is requested from those who use them. There is a rather good commercial potential with this hiking.osm.be project, for instance to propose some paper maps to sell in touristic places, but so far we did not take the time to develop it.
BTW, I’ve discovered that the style has already been used by tourist operators in Belgium to print maps on tourist boards. Finally, I use it from time to time to create large-format maps for friends or family, or just for myself like this large 2 x 1m map of the Semois river. And there’s also an OpenArdenneMap tile server, although the style is primarily intended for printing, not the web.
3. What are the unique challenges and pleasures of mapping hiking maps, especially those designed to be printed? What aspects of the projects should the rest of the world be aware of?
There are huge challenges in making printable maps from OpenStreetMap data, and I think a lot of them haven’t been addressed yet. When you look at old topographic maps, they are generally of great graphic quality and have great aesthetic power. For me, topographic maps generated from geographic data don’t have the same power, for all sorts of reasons.
Clearly, a breakthrough came when cartographers created maps from geographic data instead of drawing them on paper. About ten years ago, I learnt that cartographers at the Belgian IGN did not necessarily digitize features on aerial images according to their exact location but according to a ‘cartographic common sense’: this means that they took certain liberties with the position of some features, in order to think straight away about creating the map.
In OpenStreetMap, there’s this famous principle: ‘Don’t map for the renderer’. Of course I understand that, but if you want a map, you want to map for the renderer. My leitmotif for the future of OpenArdenneMap is precisely this: to find techniques for moving from a geographic database to a printed map. This involves a whole host of techniques that are currently very little used in the OpenStreetMap community: cartographic generalisation, displacement, etc. - in short, all the cartographic techniques that have been theorised and put into practice throughout the development of cartography.
In this sense, I agree with Christof Horman’s analysis: even if the ‘carto’ style is a fabulous work of cartography and probably the most advanced cartographic style built from OpenStreetMap data, it is still a long way from the best cartographic practices. And the same applies to all the styles derived from OpenStreetMap using Mapnik or QGIS: they fail to produce high-quality topographic maps. Of course, you could argue that a manual pass is always needed to refine a map made with an automatic style, and this is probably still true, even in the age of artificial intelligence. But apart from that, there is clearly a lack of basic cartographic work that is still not applied in styles, or even implemented in algorithms. This is a long-term project that I’d like to carry out: a review of the use of advanced mapping techniques in the OpenStreetMap ecosystem.
To come back to OpenArdenneMap, as its name suggests, it’s designed for one region in particular: the Ardennes. A friend once asked me to produce a map of Brittany using OpenArdenneMap and then complained that the sea didn’t appear. Of course, there’s no sea in the Ardennes. Far from any chauvinism or nationalism, the idea is to create a rendering specific to a region, with its own characteristics and particular objects, and of course this can evolve over time. For example, there is a specific rendering in OpenArdenneMap for Christmas tree plantations, because they cover a large area in the Ardennes, perhaps 10% of the agricultural area. But this is a recent development, and it’s possible that in a few decades there won’t be any left.
One disadvantage of web maps is that we are witnessing a standardisation of styles, with styles that can be designed for a Californian environment and then applied in Europe: this makes no sense. Each region has its own geographical richness, the result of the evolution of the natural landscapes inhabited by the human communities who have lived there. And so each region is entitled to its own styles, which highlight its characteristics.
4. What have you learned? What is the best way for people to do something similar in their city or region or country?
I try to collect maps from my region and elsewhere, and compare them. This gives me ideas for developing new things in my cartographic style. OpenArdenneMap is a rather “vintage” style, but I also like to add more recent elements to the landscape, like wind turbines. I don’t do it enough, but I also try to follow what’s being done in other mapping projects like OpenTopoMap or the ‘carto’ style of osm.org. For example, I’ve taken up the idea of automatically orienting the names of water bodies according to their shape. Or orienting sports fields and church symbols according to their actual orientation on the ground.
A cartographic style affects many things: for example, you can spend a lot of time choosing suitable fonts. For OpenArdenneMap, I chose a font made in Belgium via a magazine, Medor.coop, and then I finally met its designer, who is also a cartography enthusiast. It’s the Alfphabet font, which reproduces a font used in the 1950s. In OpenArdenneMap, I try to display a lot of labels, so the font is important.
I also like drawing symbols and pattern symbols. I’m not very good at drawing in general, and I can’t see myself creating logos, but for map symbols, I find it quite easy.
Then there’s printing. That’s quite an art too! I’ve learnt the difference between offset and digital printing. Older maps were often printed in offset with true colours: this enhances their quality. This is one of the reasons why OpenArdenneMap only has 3 colours + black: it allows offset printing with true colours.
For those who want to start a cartographic style, I recommend starting with an existing style (in Mapnik or QGIS) and then gradually changing the colours, textures, what is displayed and what is not, etc. If you want to define a style that is available for several scales, starting from a blank page takes an enormous amount of time.
5. What steps could the global OpenStreetMap community take to help support projects like this?
I love seeing new cartographic projects being created. And we certainly still need to maintain the old ones, in any case there is potential for improvement even in old styles. As I said earlier, there’s a lack of techniques and algorithms that can be used for cartographic generalisation, specifically with OpenStreetMap data. One of the challenges of OpenStreetMap data is its lack of completeness and uniformity: sometimes you have to avoid to represent something on a map if it isn’t mapped everywhere. For example, I won’t show isolated trees if their distribution in my map area is too irregular. But for this kind of problem, it’s more up to the cartographer to find or develop algorithms for data preparation and cartographic generalisation.
I think there’s a lack of documentation on existing cartographic projects. At the same time, we probably don’t have enough experience of creating maps with OpenStreetMap.
6. Last year OpenStreetMap celebrated 20 years. As someone who has been very active in OpenStreetMap for a long time, where do you think the project will be in another 20 years?
I’m sure that the project will still be there, with its community. It may be difficult to recruit new contributors, but I’m not so sure. Already today, most people use OpenStreetMap without knowing it, because OSM data is integrated into a lot of different applications. This will certainly increase in the future. Perhaps whole areas of OSM use will be supplanted by other databases, for example for the road network, addresses or POIs. But the project will always be there for mapping enthusiasts. Maybe it will be reserved more for hobbyists.
In Belgium, we are increasingly approached by public authorities who are interested in contributing to OpenStreetMap, for example by local authorities who tell us about changes in the road network. We’re also trying to get public authorities to reuse the data, and there are more and more use cases. I’m sure that this will continue to develop in Belgium.
Thank you, Julien, for taking the time to share your insights. Wonderful. As an avid hiker, I love this style. But most of all I love the perspective that we need a rich diversity of mapping styles to capture the rich diversity of the world. And open data and open source tools make it possible.
Anyone who wants to stay up to date on the project can watch it on GitHub. You can reach Julien on mastodon.
Happy mapping,
Ed
Please let us know if your community would like to be part of
our interview series
here on our blog. If you are or know of someone we should interview, please get in touch, we’re always looking to promote people doing interesting things with open geo data.
OpenStreetMap Blogs
Jacobina, BA
Rapid Editor 
►
►
a report on the OpenStreetMap 
a mapping talk series titled ‘Improving Data Quality of Road Mapping’. The session featured M. Iqnaul Haq, Maps Ops Manager at GoTo Group, who discussed the crucial 
every Japanese edition of weeklyOSM on YouTube? Would you also like to contribute to the success of OpenStreetMap? Then consider creating a YouTube channel in your language as well.
El Humedal El Totoral es un ecosistema estratégico que enfrenta diversas presiones ambientales, como la expansión agrícola y ganadera, la urbanización descontrolada y el uso inadecuado de agroquímicos. Para comprender mejor estos problemas y generar datos abiertos sobre el territorio, organizamos una jornada de mapeo comunitario con ChatMap, una herramienta innovadora para la ciencia ciudadana.
