[mapserver-users] Make PROJECTION mandatory?

Rahkonen Jukka (MML) jukka.rahkonen at maanmittauslaitos.fi
Mon Apr 27 06:36:33 PDT 2020


Hi,

Recent Mapserver buids require PROJ and GDAL https://mapserver.gis.umn.edu/ja/development/rfc/ms-rfc-127.html. That means that every Mapserver can support PROJECTION blocks both at the MAP level and within LAYER. And because there are no more builds without Proj support there is no real need for writing mapfiles without PROJECTION blocks. Therefore I suggest that such mapfiles should be considered invalid in the future. If it is for some reason too strict requirement, what if we at least edit the documentation https://mapserver.org/mapfile/projection.html so that it really encourages users to write the PROJECTION blocks. GetCapabilities could also show something like
<!-- WARNING: No explicit source projection defined for layer 'my_layer'. -->

Having layers without PROJECTION saves users from writing this much text:
"PROJECTION "init=epsg:3857" END
but when the user meets any problem with accessing data or rendering the first thing to check is the projection. In the mailing list it means one more question-answer round before getting closer to the real problem - if the problem was not in the projection, as it very often is.

If source data are in local coordinate system it would be better to define also that explicitly with a special keyword like PROJECTION "LOCAL".

Would other user consider making projection compulsory rather as an improvement or inconvenience?

-Jukka Rahkonen-
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