[OSM-talk] 1) Messy Overlapping 2) Messy Layers 3) Bridges 4) Trunk/primary 5) Forum

[Tom Chance]

Ahoy,

On Sunday 11 February 2007 00:53:25 Ben Robbins wrote:
> 5 problems I have...please split up into seperate topics for reply.  Check
> image for refernces..
>
> http://i57.photobucket.com/albums/g226/ben_robbins_/osm3things.png
>
> 1)  Where different highway types meet at junctions it usually renders
> quite a messy overlap of the core where 1 of the cores renders later and
> has a rounded end.  In just adding an additional tag (for the purpose of
> the example I have added core=yes) you can make selected cores render again
> later and clean up junctions.  What would a good tag for this be? or...are
> there better methods of sorting out this asthetical fault?.

If things look wrong in the slippy map or your own Osmarender renders, don't 
tag your way around the problems! Report the problems with mapnik and 
osmarender and wait for them to be fixed, but keep the tags in the database 
clean.

If you want to get maps looking nice for your own purposes then you can always 
save the OSM file and fiddle with it on your hard drive, but don't upload the 
hacks to the database.

Otherwise when the problem is fixed in mapnik/osmarender your hacks may have 
unintended effects, and it all becomes difficult to keep clean.

For example, golf courses still render as grey blobs in mapnik. I might be 
tempted to add 'leisure=park' to get them green for now, but I might forget 
about it and then leave the data incorrectly tagged. Even worse I might 
invent tags, add them to my osmarender rules and then upload them to the 
database. Later on those same tags could be added to the official map 
features list but with very different meanings. Suddenly my data shows up 
funny for everyone else!

If you report problems on http://trac.openstreetmap.org then everyone knows 
about them and they're likely to eventually get fixed.


> 3)  Bridges....  I've been adding them for quite some time, and now there
> is the bridge=yes rendereding.  I stated why I thourght this tag was
> inconsistent before, but I am more concerned with the way the problem of
> bridges has been approuched.  I have a bad feeling that there are so many
> different forms and odd and excentric bridges in the world, that just
> adding a tag and trying to render them correct is not going to always be
> satisfactory.
[snip]
> In the end I think drawing a map with a pencil and paper will have far less
> hurdles than osm is having/will face, just becuase it has no rules.

I suppose it's again a case of: proposed a proper fix, or work around it in 
your own way. If you can think of a good way to represent bridges without 
making the map features schema horribly complex then propose it on the wiki, 
discuss it on this list, and if it gets accepted then go ahead and use it. 
Otherwise just take renders and tweak them manually yourself. I don't think 
we can expect all the really good maps to come from automatic tools. I 
certainly spent quite a while in Inkscape to get these: 
http://cf.acrewoods.net/ethical_map

I can't actually think of any particularly odd bridges. Do you have any 
photos / maps of examples? Why would there be a bridge without some kind of 
path/road/rail across it? :o)

Regards,
Tom

-- 
| Green Party Speaker on Intellecual Property and Free Software |
| http://tom.acrewoods.net    ::   http://www.greenparty.org.uk |