Map style licensing – another comment


Earlier this year i wrote a bit about map style licensing. The OSMF has just added a new featured tile layer on the website – and i wanted to quickly point out an interesting quirk in that regard here.

First – the tile layer added is an interesting mashup of OSM-Carto and OpenTopoMap – and individual styling ideas integrated from other map styles and from map development discussion on public channels. If i had to specify a unique and interesting aspect of the style in terms of the guidelines for new tile layers that would be the mashup aspect. It is not the first style that combines design elements developed independently into a distinctly and deliberately heterogeneous design, but it is definitely a noteworthy example of that.

However, the style is not open source and as you might know (i mentioned it in January) OpenTopoMap is licensed under CC-BY-SA. So unless Tracestrack has obtained an explicit license for non-open use from the OpenTopoMap developers we are having a clear license violation here.

The freedom to recombine different design elements and to create mashups is an important and attractive aspect of Open Source map design. But you still have to respect the licenses.


  1. Hi chris, your second link is pointing to != 🙂

  2. Hi Chris,

    Your article came to my attention. First of all we do plan to open source the topo base map (excluding label layers to begin with) soon, under the same license CC BY-SA 4.0. But that is unrelated to the OTM license requirement. As you may see in the map, only relief/hillshades/contours are similar to OTM. The method is described in Should an open source repository license cover a method described in it? I’m not sure.

    • Thanks for the comment. I cannot provide case specific consultation here on map style licensing. Feel free to contact me directly if you have questions about this. I wrote some more general comments on the matter some time ago here which might help.

      Your style is a derivative of both OSM-Carto and OpenTopoMap. As such it is subject to the requirements of the respective licenses of these styles regarding derivative works. If the resulting map is subjectively similar to OpenTopoMap is not significant in that regard.

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