FOSS4G 2022 general tracks

Web Mapping as a technology and a method is now twenty years old. Within the
OSGeo Community, it has been fostered by projects such as OpenLayers
and Leaflet. They evolved tightly intertwined with the framework imposed by
free data providers, initially around commercial efforts like Google and later
OpenStreetMap. While useful in providing an easy entry to web mapping, and
convenient background layers, these data providers also triggered a regression
towards centuries-old cartography techniques, in particular the Mercator projection.
This has become a major hurdle to web mapping, particularly concerning global
data.

The Mercator map projection was created to aid sea faring in the XVI century and
was rendered useless with the advent of global positioning systems. Its use in
cartography may still be acceptable at large scales, neighbourhood or city
level, but at smaller scales it imposes severe distortion to distances and areas.
For global datasets in particular, the Mercator projection is unusable, for it
cannot represent the full surface of the planet.

Web mapping developers may work around this framework with libraries such as D3
or proj4js, and by setting up bespoke base layer services. But in doing so they
face a different problem: the deep dependence on the CRS index created by the
European Petroleum Survey Group (EPSG). Primarily concerned with the survey and
extraction of fossil fuels, the EPSG leans heavily on local or regional CRSs,
largely ignoring global CRSs. Hardly any of the more than 100 map projections
and coordinate systems developed since the beginning of the XX century feature
in the EPSG index. Landmark projections such as the Eckert series, the
Homolosine, Eumorphic, Dymaxion or the Snyder series were never included in the
EPSG index. Not even the classical Mollweide projection (one of the turning
points towards modern cartography) appears in the EPSG index. With a FOSS4G
stapple such as MapServer, this forces the leveraging of map (re-)projections to
the client, which is not always possible.

Web mapping with global data thus remains a technical challenge with FOSS4G.
This address reviews several techniques and work-arounds making global web
mapping possible with familiar FOSS4G technologies. Starting with the
appropriate configuration of CRS managing software, going through the set-up of
data servers and finally providing examples with web mapping clients.