[mapserver-dev] RFC-108 : heatmap generation

[Thomas Bonfort]

> Interestingly they support any geometry by simply taking its centroid if
> it's not a point. Perhaps that is a viable solution for Mapserver too.

We could probably use layer level geomtransforms for that. Looking
through the code however this won't work out of the box as the
implementation for RFC89 only works for EXPRESSION type geomtransforms
(i.e. not the CENTROID one).