[MapServer-dev] Rendering Openstreetmap data in Mapserver

[Tamas Szekeres]

In my understanding, the actual value should be provided somewhere here:

https://github.com/MapServer/MapServer/blob/89d81cb8d0fcf5d44e043d53afe70f6e6a785756/src/maputil.c#L713

in a similar way as the geomtransform code:

https://github.com/MapServer/MapServer/blob/89d81cb8d0fcf5d44e043d53afe70f6e6a785756/src/mapgeomtransform.c#L283

Best regards,

Tamas


Lime, Steve D (MNIT) <steve.lime at state.mn.us> ezt írta (időpont: 2026.
márc. 5., Cs, 23:17):

> Hmmm… I think this should be possible but I’m not sure exactly what would
> need to change. The expression parser code is not particularly
> straightforward. The map_cellsize token is generally recognized in the
> parser – so not limited to GEOMTRANSFORM but it’s not clear how it gets its
> value.
>
>
>
> *From:* MapServer-dev <mapserver-dev-bounces at lists.osgeo.org> *On Behalf
> Of *Tamas Szekeres via MapServer-dev
> *Sent:* Thursday, March 5, 2026 2:32 PM
> *To:* mapserver-dev at lists.osgeo.org
> *Subject:* [MapServer-dev] Rendering Openstreetmap data in Mapserver
>
>
>
> Hi Devs,
>
>
>
> I'm trying to create a vector based map for the openstreetmap data in
> Mapserver by utilizing the mapnik styles provided by the
> openstreetmap-carto
> <https://github.com/openstreetmap-carto/openstreetmap-carto> project. So
> far, I could achieve a very good result and the map looks is very similar
> to the online OSM at all scales, however the only thing I cannot replicate
> is the concept of the *[way_pixels]* attribute conditions, where the
> feature’s area in pixels at the current map scale should be the part of the
> class expressions. I don't see such an option in Mapserver as it stands
> now, but supporting the already existing *[map_cellsize] *would be a very
> close solution I think, however that is only implemented for the
> GEOMTRANSFORM expressions actually.
>
>
>
> For example the mapnik style expression
>
>
>
> [way_pixels] > 750
>
>
>
> could be provided in a MapServer CLASS expression as somehing like:
>
> [way_area] > 750 * [map_cellsize] * [map_cellsize]
>
> Would that be reasonable to implement *[map_cellsize]* in the CLASS
> expressions?
>
>
>
> Best regards,
>
>
>
> Tamas
>
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