Earlier this year i wrote a bit about map style licensing. The OSMF has just added a new featured tile layer on the openstreetmap.org 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.