[OSM-dev] What about sharing basic rendering rules and using SLD?

[Richard Fairhurst]

Frederik Ramm wrote:

> [...]
> Whenever I do a custom Osmarender style, I usually start with the  
> z17 style sheet which contains almost "everything"; it is much more  
> convenient to take that and remove everything I don't want than to  
> start with, say, a z12 style and insert all the extra presentation  
> rules I might need.

Sure, but there's a big difference between sharing a rules file for  
two scales of the same cartography, and sharing a rules file for two  
cartographies. In my (non-OSM) Illustrator map work I've often done  
(the equivalent of) the former, but never the latter.

(Why the hell are we still trying to do [carto-]graphic design in  
text files anyway? I mean, the rest of the world got WYSIWYG in about  
1984...)

> [...]
> And another thing:
> > One of the things I like best about Steve (Chilton)'s Mapnik
> > cartography is that it doesn't try to render "all these keys".
>
> This is not a special feature of the Mapnik cartography but of  
> every single OSM cartography I've seen to date. - Just in case you  
> were trying to suggest that the Osmarender guys would thoughtlessly  
> clutter their maps. Which you weren't of course ;-)

Indeed not - just because I like something about Steve's cartography  
doesn't preclude the option that other cartographers may follow a  
similar principle!

But, to my mind, that actually underlines why a shared-rules approach  
wouldn't work - if "every single OSM cartography" only shows selected  
tags, then their selections will differ. (As, indeed, will the  
designs chosen to represent each tag.) At which point I fail to see  
what shared rules bring to the party. YMMV, of course.

The real challenge IMO is not "creating rules files is hard, so let's  
have one rule file for all three renderers", it's "creating rules  
files is hard, so let's make it easier"... and it's good to see  
progress being made on WYSIWYG tools, finally relegating the "rules  
file" itself to the internal storage format it should be.

Of course, if you were to propose a cartographic design utility that  
could output a rules file in either Mapnik or Osmarender format...  
well, _then_ you'd be talking.

cheers
Richard